WorldWideScience

Sample records for cation exchange separations

  1. Separation of Clay Minerals from Host Sediments Using Cation Exchange Resins

    Institute of Scientific and Technical Information of China (English)

    I.S. Ismael; H.M. Baioumy

    2003-01-01

    Classic physical and chemical treatments applied to separating clay minerals from the host sediments are often difficult or aggressive for clay minerals. A technique using cation exchange resins (amberlite IRC-50H and amberlite IR-120) is used to separate clay minerals from the host sediments. The technique is based on the exchange of cations in the minerals that may be associated clay minerals in sediments,such as Ca and Mg from dolomite; Ca from calcite,gypsum and francolite with cations carried by resin radicals. The associated minerals such as gypsum,calcite,dolomite and francolite are removed in descending order. Separation of clay minerals using cation exchange resins is less aggressive than that by other classic treatments.The efficiency of amberlite IRC-50H in the removal of associated minerals is greater than that of amberlite IR-120.

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

    Science.gov (United States)

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

    2013-11-01

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

  3. Separation of proteins by cation-exchange sequential injection chromatography using a polymeric monolithic column.

    Science.gov (United States)

    Masini, Jorge Cesar

    2016-02-01

    Since sequential injection chromatography (SIC) emerged in 2003, it has been used for separation of small molecules in diverse samples, but separations of high molar mass compounds such as proteins have not yet been described. In the present work a poly(glycidyl methacrylate-co-ethylene dimethacrylate) (GMA-co-EDMA) monolithic column was prepared by free radical polymerization inside a 2.1-mm-i.d. activated fused silica-lined stainless steel tubing and modified with iminodiacetic acid (IDA). The column was prepared from a mixture of 24% GMA, 16% EDMA, 20% cyclohexanol, and 40% 1-dodecanol (all% as w/w) containing 1% of azobisisobutyronitrile (AIBN) (in relation to monomers). Polymerization was done at 60 °C for 24 h. The polymer was modified with 1.0 M IDA (in 2 M Na2CO3, pH 10.5) at 80 °C for 16 h. Separation of myoglobin, ribonuclease A, cytochrome C, and lysozyme was achieved at pH 7.0 (20 mM KH2PO4/K2HPO4) using a salt gradient (NaCl). Myoglobin was not retained, and the other proteins were separated by a gradient of NaCl created inside the holding coil (4 m of 0.8-mm-i.d. PTFE tubing) by sequential aspiration of 750 and 700 μL of 0.2 and 0.1 M NaCl, respectively. As the flow was reversed toward the column (5 μL s(-1)) the interdispersion of these solutions created a reproducible gradient which separated the proteins in 10 min, with the following order of retention: ribonuclease A < cytochrome C < lysozyme. The elution order was consistent with a cation-exchange mechanism as the retention increased with the isoelectric points.

  4. Preparation of decarboxylic-functionalized weak cation exchanger and application for simultaneous separation of alkali, alkaline earth and transition metals.

    Science.gov (United States)

    Peng, Yahui; Gan, Yihui; He, Chengxia; Yang, Bingcheng; Guo, Zhimou; Liang, Xinmiao

    2016-06-01

    A novel weak cation exchanger (WCX) with dicarboxyl groups functionalized has been developed by clicking mercaptosuccinic acid onto silica gel. The simple synthesis starts with modification of silica gel with triethoxyvinylsilane, followed by efficient coupling vinyl-bonded silica with mercaptosuccinic acid via a "thiol-ene" click reaction. The obtained WCX demonstrated good separation and high selectivity towards common metals. Simultaneous separation of 10 alkali, alkaline earth and transition metals was achieved within 12min. Ion exchange and complex mechanism dominates the separation process. Its utility was demonstrated for determination of metals in tap water. PMID:27130093

  5. Separation of matrine and oxymatrine from Sophora flavescens extract through cation exchange resin coupled with macroporous absorption resin

    Directory of Open Access Journals (Sweden)

    Chen Haohao

    2016-06-01

    Full Text Available A simple method for separation of matrine and oxymatrine from Sophora flavescens was developed with cation exchange resin coupled with macroporous resin. Based on the adsorption characteristics of matrine and oxymatrine, 001×732 cation exchange resin was used to absorb target alkaloids for removing most of the foreign matter, while BS-65 macroporous resin was chosen to purify these alkaloids. The result showed that the equilibrium adsorption data of matrine and oxymatrine on 001×732 resin and BS-65 resin at 30°C was fitted to Langmuir isotherm and Freundlich isotherm, respectively. The contents of matrine and oxymatrine were increased from 0.73% and 2.2% in the crude extract of the root of Sophora flavescens to 67.2% and 66.8% in the final eluent products with the recoveries of 90.3% and 86.9%, respectively.

  6. On-line coupling of an ion chromatograph to the ICP-MS: Separations with a cation exchange chromatography column

    Energy Technology Data Exchange (ETDEWEB)

    Roellin, Stefan [Studsvik Nuclear AB, Nykoeping (Sweden)

    1999-12-01

    An ion chromatography system was coupled on-line to the ICP-MS. All separations were made with a cation exchange chromatography column. Fundamental laws about elution parameters affecting individual retention times and elution forms are explained by applying a proper ion exchange mechanism for the isocratic elution (separations with constant eluent concentration) of mono-, di-, tri-, and tetravalent cations and the actinide species MO{sub 2}{sup +} and MO{sub 2}{sup 2+}. A separation method with two eluents has been investigated to separate mono- from divalent ions in order to separate isobaric overlaps of Rb/Sr and Cs/Ba. The ions normally formed by actinides in aqueous solutions in the oxidation states III to VI are M{sup 3+}, M{sup 4+}, MO{sub 2}{sup +} and MO{sub 2}{sup 2+} respectively. Elution parameters were investigated to separate all four actinide species from each other in order to separate isobaric overlaps of the actinides Np, Pu, U and Am. A major question of concern over the possible release of actinides to the environment is the speciation of actinides within their four possible oxidation states. To check the possibility of speciation analysis with ion chromatography, a separation method was investigated to separate U{sup 4+} and UO{sub 2}{sup 2+} without changing the redox species composition during the separation. First results of Pu speciation analysis showed that Pu could be eluted as three different species. Pu(VI) was always eluting at the same time as Np(V). This was surprising as Pu(VI) is expected to have the same chemical characteristics as U(VI) and thus was expected to elute at the same time as U(VI)

  7. Toward Separating Alpha-lactalbumin and Beta-lactoglobulin Proteins from Whey through Cation-exchange Adsorption

    Science.gov (United States)

    El-Sayed, Mayyada; Chase, Howard

    2009-05-01

    This paper describes the cation-exchange adsorption of the two major whey proteins, alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG) with the purpose of establishing a process for isolating them from cow's milk whey. The single- and two-component adsorption of 1.5 mg/ml ALA and 3 mg/ml BLG to the cation-exchanger SP Sepharose FF at 20° C using 0.1 M acetate buffer of pH 3.7 was studied. Langmuir isotherm parameters were determined for the pure proteins. In two-component systems, BLG breakthrough curve exhibited an overshoot phenomenon that gave evidence for the presence of a competitive adsorption between the two proteins. Complete separation occurred and it was possible to obtain each of the two proteins in a pure form. The process was then applied to a whey concentrate mixture where incomplete separation took place. However, BLG was produced with 95% purity and a recovery of 80%, while ALA showed an 84% recovery with low purity.

  8. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column

    Institute of Scientific and Technical Information of China (English)

    Kaori ARAI; Masanobu MORI; Takahiro HIRONAGA; Hideyuki ITABASHI; Kazuhiko TANAKA

    2012-01-01

    A combination of hydrophilic interaction chromatographic ( HILIC ) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography ( IC ).Firstly,the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions.The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetainezwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10).When using tartaric acid as the eluent,the HILIC columns indicated strong retentions for anions,based on ion-pair interaction.Especially,HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I- > NO3- > Br- > Cl- >H2PO4-.However,since HILIC-10 could not separate analyte cations,a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series.The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+,NH4+,K+,Mg2+,Ca2+,H2PO4-,Cl-,Br-,NO3- and I-) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6.The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections.The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 μmol/L for the cations and 0.31 - 1.2 μmol/L for the anions.This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.

  9. Proteomics-based, multivariate random forest method for prediction of protein separation behavior during cation-exchange chromatography.

    Science.gov (United States)

    Swanson, Ryan K; Xu, Ruo; Nettleton, Dan; Glatz, Charles E

    2012-08-01

    The most significant cost of recombinant protein production lies in the optimization of the downstream purification methods, mainly due to a lack of knowledge of the separation behavior of the host cell proteins (HCP). To reduce the effort required for purification process development, this work was aimed at modeling the separation behavior of a complex mixture of proteins in cation-exchange chromatography (CEX). With the emergence of molecular pharming as a viable option for the production of recombinant pharmaceutical proteins, the HCP mixture chosen was an extract of corn germ. Aqueous two phase system (ATPS) partitioning followed by two-dimensional electrophoresis (2DE) provided data on isoelectric point, molecular weight and surface hydrophobicity of the extract and step-elution fractions. A multivariate random forest (MVRF) method was then developed using the three characterization variables to predict the elution pattern of individual corn HCP. The MVRF method achieved an average root mean squared error (RMSE) value of 0.0406 (fraction of protein eluted in each CEX elution step) for all the proteins that were characterized, providing evidence for the effectiveness of both the characterization method and the analysis approach for protein purification applications. PMID:22748375

  10. Proteomics-based, multivariate random forest method for prediction of protein separation behavior during cation-exchange chromatography.

    Science.gov (United States)

    Swanson, Ryan K; Xu, Ruo; Nettleton, Dan; Glatz, Charles E

    2012-08-01

    The most significant cost of recombinant protein production lies in the optimization of the downstream purification methods, mainly due to a lack of knowledge of the separation behavior of the host cell proteins (HCP). To reduce the effort required for purification process development, this work was aimed at modeling the separation behavior of a complex mixture of proteins in cation-exchange chromatography (CEX). With the emergence of molecular pharming as a viable option for the production of recombinant pharmaceutical proteins, the HCP mixture chosen was an extract of corn germ. Aqueous two phase system (ATPS) partitioning followed by two-dimensional electrophoresis (2DE) provided data on isoelectric point, molecular weight and surface hydrophobicity of the extract and step-elution fractions. A multivariate random forest (MVRF) method was then developed using the three characterization variables to predict the elution pattern of individual corn HCP. The MVRF method achieved an average root mean squared error (RMSE) value of 0.0406 (fraction of protein eluted in each CEX elution step) for all the proteins that were characterized, providing evidence for the effectiveness of both the characterization method and the analysis approach for protein purification applications.

  11. Ion exchange behaviour of polymeric zirconium cations

    International Nuclear Information System (INIS)

    Polymeric zirconium cations formed in weakly acid solutions (pH2) are taken up strongly into macroporous cation exchange resins, while uptake into normal cation exchange resins (pore diameter about 1 nm) is low. Macroporous cation exchange resins loaded with polymeric Zr cations are shown to function as ligand exchange sorbents. (Authors)

  12. Dynamics of the separation of amino acid and mineral salt in the stationary dialysis of solutions with an MK-40 profiled sulfo group cation exchange membrane

    Science.gov (United States)

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

    2012-11-01

    The conjugated diffusion transport of amino acid and mineral salt through a profiled sulfo group cation exchange membrane that simulates the extraction of amino acid from wash waters of microbiological production containing mineral components not used in synthesis is studied. The competitive nature of the conjugation of flows resulting in a decrease in the rate of the mass transfer of components and their separation factor is established from a comparative analysis of experimental data on the diffusion transfer of phenylalanine and sodium chloride in the form of hydrogen from individual and mixed solutions through a profiled sulfo group cation exchange membrane. The range of concentrations and the ratio of components in solution corresponding to the effective separation of phenylalanine and sodium chloride are determined.

  13. A cation exchange method for separation of 111In from inactive silver, copper, traces of iron and radioactive gallium and zinc isotopes

    International Nuclear Information System (INIS)

    111In was produced by the 109Ag(α, 2n)111In reaction. A simple radiochemical separation technique, using Dowex-50 cation exchange resin (with prior removal of copper bulk, if present), has been employed to separate radioindium from inactive contaminants like Ag, Cu, Fe and active contaminant like 67Ga and 65Zn. The radiochemical separation yield was 90-99%. The radionuclide purity of 111In was >99% at 60 h after EOB. The level of all the inactive contaminants was <5 μg/mL in the final product. (Author)

  14. Organometallic cation-exchanged phyllosilicates

    OpenAIRE

    Fleming, Shay

    1991-01-01

    Organotin (IV) complexes formed between 0 01 M dimethyltin dichloride solutions prepared at pH 2 6 and 4 0, and trimethyltin chloride prepared at pH 3 4, with Na- 119 montmori 1lonite clay have been characterised using Sn Mflssbauer spectroscopy, X-ray diffraction, thermogravimetric analysis and water sorption isotherms Following cation exchange, Mttssbauer spectroscopy identified two tin species in the dimethyltin (IV)-exchanged clay prepared at pH 2 6 A cis specie...

  15. Features definition exchange cations in sedimentary rocks.

    OpenAIRE

    Bilec'ka V.A.

    2008-01-01

    The research method of determination of exchange cations in calcareous sedimentary rocks of different extractants, the influence of the ratio between the solid and liquid phases on extrusion exchange cations.

  16. Features definition exchange cations in sedimentary rocks.

    Directory of Open Access Journals (Sweden)

    Bilec'ka V.A.

    2008-05-01

    Full Text Available The research method of determination of exchange cations in calcareous sedimentary rocks of different extractants, the influence of the ratio between the solid and liquid phases on extrusion exchange cations.

  17. Sequential Determination of Total Arsenic and Cadmium in Concentrated Cadmium Sulphate Solutions by Flow-Through Stripping Chronopotentiometry after Online Cation Exchanger Separation

    Directory of Open Access Journals (Sweden)

    Frantisek Cacho

    2012-01-01

    Full Text Available Flow-through stripping chronopotentiometry with a gold wire electrode was used for the determination of total arsenic and cadmium in cadmium sulphate solutions for cadmium production. The analysis is based on the online separation of arsenic as arsenate anion from cadmium cations by means of a cation exchanger. On measuring arsenate in the effluent, the trapped cadmium is eluted by sodium chloride solution and determined in a small segment of the effluent by making use of the same electrode. The elaborated protocol enables a full automatic measurement of both species in the same sample solution. The accuracy of the results was confirmed by atomic absorption spectrometry. The LOD and LOQ for Arsenic were found to be 0.9 μg dm-3 and 2.7 μg dm-3, respectively. A linear response range was observed in the concentration range of 1 to 300 μg dm-3 for sample volumes of 4 mL. The repeatability and reproducibility were found to be 2.9% and 5.2%, respectively. The linear response range for cadmium was found to be 0.5 to 60 g/L. The method was tested on samples from a cadmium production plant.

  18. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  19. Liquid-liquid extraction and separation of VIII group elements, especially ruthenium, by synergic combinations or aromatic polyimines and micellar cationic exchangers

    International Nuclear Information System (INIS)

    This thesis aims to characterize and to quantify the chemical equilibria involved in d-elements liquid-liquid extraction systems, especially elements belonging to the VIII group (Fe, Ni, Co, Ru, Rh, Pd, Pt). These systems are composed of synergic combination of aromatic polyimines and micellar cationic exchangers. Substitutions are first performed in aqueous acidic media by aromatic polyimines; then extractions are operated using micellic canionic exchangers. Chemical equilibria, selectivity effects, especially those due to ion-pair formations, kinetics, extractant behaviour are analysed and quantified

  20. Forging Colloidal Nanostructures via Cation Exchange Reactions

    Science.gov (United States)

    2016-01-01

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  1. Synthesis and characterization of a new cation exchanger-zirconium(IV)iodotungstate: Separation and determination of metal ion contents of synthetic mixtures, pharmaceutical preparations and standard reference material

    International Nuclear Information System (INIS)

    Samples of zirconium(IV)iodotungstate have been synthesized under varying mixing order and ratios of aqueous solution of potassium iodate, sodium tungstate and zirconium oxychloride at pH 1. A tentative formula was proposed on the basis of chemical composition, FTIR and thermogravimetric studies. The material shows a capacity of 0.68 meq g-1 (for K+) which can be retained up to 200 deg. C. pH titration data reveal its monofunctional behavior. The distribution coefficient values of metal ions have been determined in various solvent systems. A number of important and analytically difficult quantitative separations of metal ions have been achieved using columns packed with this exchanger. In order to demonstrate practical utility of this material, Hg2+ and Pb2+ have been selectively separated and determined in the synthetic mixtures. Assay of Al3+ and Mg2+ in commercial tablets and analysis of lead in the standard reference material have also been attempted.

  2. Cobalt 60 cation exchange with mexican clays

    International Nuclear Information System (INIS)

    Mexican clays can be used to remove radioactive elements from contaminated aqueous solutions. Cation exchange experiments were performed with 60 Co radioactive solution. In the present work the effect of contact time on the sorption of Co 2+ was studied. The contact time in hydrated montmorillonite was from 5 to 120 minutes and in dehydrated montmorillonite 5 to 1400 minutes. The Co 2+ uptake value was, in hydrated montmorillonite, between 0.3 to 0.85 m eq/g and in dehydrated montmorillonite, between 0.6 to 1.40 m eq/g. The experiments were done in a pH 5.1 to 5.7 and normal conditions. XRD patterns were used to characterize the samples. The crystallinity was determined by X-ray Diffraction and it was maintained before and after the cation exchange. DTA thermo grams showed the temperatures of the lost humidity and crystallization water. Finally, was observed that dehydrated montmorillonite adsorb more cobalt than hydrated montmorillonite. (Author)

  3. Modeling cation exchange using EQ3/6

    International Nuclear Information System (INIS)

    Geochemical modeling codes must be able to predict solid-solution and ion-exchange behavior of zeolites and smectites in order to design and assess strategies for containing and cleaning up toxic and/or radioactive wastes. Cation-exchange and solid-solution models have been implemented in the EQ3/6 geochemical modeling package and used to predict the composition of clinoptilolite under a variety of conditions. Published free energies of cation exchange on clinoptilolite at 25 degrees C were combined with the calorimetric data for clinoptilolite to derive free energies of formation of the component end members of a solid solution in which mixing is allowed only on the exchange site. The solid-solution model and component end-member data were incorporated into EQ3/6 and its data base. An option to treat cation exchange independently of the solid-solution model was also developed and implemented in EQ3/6. This option allows the user to model mixed-phase exchangers, multisite exchangers, and systems in which the exchanger is not in overall equilibrium with the solution. Two open-quotes idealclose quotes cation-exchange conventions [Vanselow (mole fraction) and Gapon (equivalent fraction)] are currently implemented in the code. A description of the cation-exchange models and their implementation into EQ3/6 is presented, and the relationship between the exchange formalisms and the solid-solution models is discussed. The advantages and limitations of the models and currently available thermodynamic data are addressed by comparing cation-exchange compositions of clinoptilolites with (1) published binary exchange data; (2) compositions of coexisting clinoptilolites and formation waters at Yucca Mountain; and (3) experimental sorption isotherms of Cs and Sr on zeolitized tuff

  4. Microscopic Theory of Cation Exchange in CdSe Nanocrystals

    OpenAIRE

    Ott, Florian D.; Spiegel, Leo L.; Norris, David J.; Erwin, Steven C.

    2014-01-01

    Although poorly understood, cation-exchange reactions are increasingly used to dope or transform colloidal semiconductor nanocrystals (quantum dots). We used density-functional theory and kinetic Monte Carlo simulations to develop a microscopic theory that explains structural, optical, and electronic changes observed experimentally in Ag-cation-exchanged CdSe nanocrystals. We find that Coulomb interactions, both between ionized impurities and with the polarized nanocrystal surface, play a key...

  5. Determination of boron in silicates after ion exchange separation

    Science.gov (United States)

    Kramer, H.

    1955-01-01

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

  6. Synthetic crystalline calcium silicate hydrate (I): cation exchange and caesium selectivity

    International Nuclear Information System (INIS)

    Solid crystalline calcium silicate hydrate (I) synthesized from equimolar amounts of Ca and Si under hydrothermal conditions at 120 oC shows cation exchange properties towards divalent metal cations such as Ni, Cu, Cd, or Hg. It also exhibits caesium selectivity in the presence of Na+. The exchange capacity and selectivity of the solid can be increased by 10 and 28 %, respectively, upon substitution of 0.01 mol of the Ca2+ in its structure by Na+. The ability of metal cation uptake by the solid was found to obey the order Ni2+ > Hg2+ > Cu2+ > Cd2+. The different affinities of calcium silicate hydrate (I) towards these ions can be used for their separation from solutions and also in nuclear waste treatment. The mechanism of the exchange reaction is discussed. (author)

  7. Multi-cycle recovery of lactoferrin and lactoperoxidase from crude whey using fimbriated high-capacity magnetic cation exchangers and a novel "rotor-stator" high-gradient magnetic separator.

    Science.gov (United States)

    Brown, Geoffrey N; Müller, Christine; Theodosiou, Eirini; Franzreb, Matthias; Thomas, Owen R T

    2013-06-01

    Cerium (IV) initiated "graft-from" polymerization reactions were employed to convert M-PVA magnetic particles into polyacrylic acid-fimbriated magnetic cation exchange supports displaying ultra-high binding capacity for basic target proteins. The modifications, which were performed at 25 mg and 2.5 g scales, delivered maximum binding capacities (Qmax ) for hen egg white lysozyme in excess of 320 mg g(-1) , combined with sub-micromolar dissociation constants (0.45-0.69 µm) and "tightness of binding" values greater than 49 L g(-1) . Two batches of polyacrylic acid-fimbriated magnetic cation exchangers were combined to form a 5 g pooled batch exhibiting Qmax values for lysozyme, lactoferrin, and lactoperoxidase of 404, 585, and 685 mg g(-1) , respectively. These magnetic cation exchangers were subsequently employed together with a newly designed "rotor-stator" type HGMF rig, in five sequential cycles of recovery of lactoferrin and lactoperoxidase from 2 L batches of a crude sweet bovine whey feedstock. Lactoferrin purification performance was observed to remain relatively constant from one HGMF cycle to the next over the five operating cycles, with yields between 40% and 49% combined with purification and concentration factors of 37- to 46-fold and 1.3- to 1.6-fold, respectively. The far superior multi-cycle HGMF performance seen here compared to that observed in our earlier studies can be directly attributed to the combined use of improved high capacity adsorbents and superior particle resuspension afforded by the new "rotor-stator" HGMS design.

  8. Denatured Thermodynamics of Proteins in Weak Cation-exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    LI Rong; CHEN Guo-Liang

    2003-01-01

    The thermostability of some proteins in weak cation-exchange chromatography was investigated at 20-80 ℃. The results show that there is a fixed thermal denaturation transition temperature for each protein. The appearance of the thermal transition temperature indicates that the conformations of the proteins are destroyed seriously. The thermal behavior of the proteins in weak cation-exchange and hydrophobic interaction chromatographies were compared in a wide temperature range. It was found that the proteins have a higher thermostability in a weak cation-exchange chromatography system. The thermodynamic parameters(ΔH0, ΔS0) of those proteins were determined by means of Vant Hoff relationship(lnk-1/T). According to standard entropy change(ΔS0), the conformational change of the proteins was judged in the chromatographic process. The linear relationships between ΔH0 and ΔS0 can be used to evaluate "compensation temperature"(β) at the protein denaturation and identify the identity of the protein retention mechanism in weak cation-exchange chromatography.

  9. New cation-exchange membranes for hyperfiltration processes

    NARCIS (Netherlands)

    Velden, van der P.M.; Smolders, C.A.

    1977-01-01

    A new route for the preparation of cation exchange membranes from polystyrene-polyisoprene-polystyrene (SIS) block copolymers has been studied, using N-chlorosulfonyl isocyanate. At temperatures of 0° to 20°C, N-chlorosulfonyl isocyanate reacts readily with the olefin group in polyisoprenes, resulti

  10. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  11. Sulfonated polyvinyl chloride fibers for cation-exchange microextraction.

    Science.gov (United States)

    Xu, Li; Lee, Hian Kee

    2009-09-18

    Polyvinyl chloride (PVC) fiber was derivatized by concentrated sulfuric acid to yield sulfonated PVC (PVC-SO3H). The PVC-SO3H fiber had dual properties as a sorbent, based on cation-exchange and hydrophobicity. In the present study, the novel fiber was used directly as an individual device for extraction purposes in the cation-exchange microextraction of anaesthetics, followed by high-performance liquid chromatography-UV analysis. The results demonstrated that this PVC-SO3H fiber-based microextraction afforded convenient operation and cost-effective application to basic analytes. The limits of detection for four anaesthetics ranged from 1.2 to 6.0 ng/mL. No carryover (because of its disposable usage), and no loss of sorbent phase (which normally occurs in stir-bar sorptive extraction) during extraction were observed.

  12. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chih-Jen [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, University of Wisconsin - Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jean, Jiin-Shuh; Liu, Chia-Chuan [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2010-11-15

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca{sup 2+} as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK{sub a2} (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d{sub 001}) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  13. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    International Nuclear Information System (INIS)

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca2+ as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pKa2 (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d001) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  14. EXCHANGE ADSORPTION EQUILIBRIA OF AMMONIUM ON CATION-VERMICULITE MINERALS

    Institute of Scientific and Technical Information of China (English)

    GUO Yaping; XIE Lianwu; WU Xiaofu

    2006-01-01

    Experiment was designed under different pH and temperature conditions to analysis the NH4+ exchange capacity of Na+-vermiculite, Ca2+-vermiculite and Mg2+-vermiculite clay minerals pre-treated using NaCl, CaCl2 and MgCl2 solutions respectively. The results indicated that the exchange reactions occurred most rapidly at the proceeding 80 minutes and approached to equilibrium by about 120 minutes. The exchange quantity of ammonium on the vermiculite (at initial ammonium concentration of 673mg/L ) varied with pH with a peak value of 28.36mg/g on Na+-vermiculite, 23.01mg/g on Ca2+-vermiculite, 20.14mg/g on Mg2+-vermiculite, 18.04mg/g on natural vermiculite at pH 7. The exchange and adsorption isotherm of NH4+ on cation-vermiculite can be described by Langmuir equation.

  15. Preparation of Weak Cation Exchange Packings Based on Monodisperse Poly (chloromethylstyrene-co-divinylbenzene) Particles and Its Chromatographic Properties

    Institute of Scientific and Technical Information of China (English)

    卫引茂; 陈强; 耿信笃

    2001-01-01

    Monodisperse poly ( chloromethylstyrene-co-divinylbenzene )particles were firstly prepared by a two-step swelling method.Based on this media, one kind of weak cation ion exchange packings was prepared. It was demonstrated that the prepared packings have comparative advantages for biopolymer separation with high column efficiency, low interstitial volume and low column backpressure, and have good resolution to proteins. The effects of salt concentration and pH of mobile phase on protein retentions were investigated. The properties of the weak cation ion exchange packings were evaluated by the unified retention model for mixed-mode interaction mechanison in ion exchange and hydrophobic interaction chromatography.

  16. Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang; Alivisatos, A. Paul

    2007-03-14

    Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.

  17. Computer simulation of methanol exchange dynamics around cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.

    2016-03-03

    In this paper, we present the first computer simulation of methanol exchange dynamics between the first and second solvation shells around different cations and anions. After water, methanol is the most frequently used solvent for ions. Methanol has different structural and dynamical properties than water, so its ion solvation process is different. To this end, we performed molecular dynamics simulations using polarizable potential models to describe methanol-methanol and ion-methanol interactions. In particular, we computed methanol exchange rates by employing the transition state theory, the Impey-Madden-McDonald method, the reactive flux approach, and the Grote-Hynes theory. We observed that methanol exchange occurs at a nanosecond time scale for Na+ and at a picosecond time scale for other ions. We also observed a trend in which, for like charges, the exchange rate is slower for smaller ions because they are more strongly bound to methanol. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

  18. THE SEPARATION OF BASE METALS FROM PLATINUM METALS BY ION EXCHANGE

    Institute of Scientific and Technical Information of China (English)

    JIANGLingen; HUANGYan

    1992-01-01

    In this paper the separation of base metals Fe,Co,Ni and Cu from the platinum metals on a cation exchanger column was studies.The convenient separation conditions are 0.5mol·dm-3 NaCl,pH=2. The recovery efficiency of Rh is 98%.

  19. Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands

    Science.gov (United States)

    Fan, Zhaochuan; Lin, Li-Chiang; Buijs, Wim; Vlugt, Thijs J. H.; van Huis, Marijn A.

    2016-05-01

    Cation exchange is a powerful tool for the synthesis of nanostructures such as core-shell nanocrystals, however, the underlying mechanism is poorly understood. Interactions of cations with ligands and solvent molecules are systematically ignored in simulations. Here, we introduce the concept of pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core-shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals.

  20. Radiochemical separation of gold by amalgam exchange

    Science.gov (United States)

    Ruch, R.R.

    1970-01-01

    A rapid and simple method for the radiochemical separation of gold after neutron activation. The technique is based on treatment with a dilute indium-gold amalgam, both chemical reduction and isotopic exchange being involved. The counting efficiency for 198Au in small volumes of the amalgam is good. Few interferences occur and the method is applicable to clays, rocks, salts and metals. The possibility of determining silver, platinum and palladium by a similar method is mentioned. ?? 1970.

  1. Carbon dioxide and nitrogen adsorption on cation-exchanged SSZ-13 zeolites.

    Science.gov (United States)

    Pham, Trong D; Liu, Qingling; Lobo, Raul F

    2013-01-15

    Samples of high-silica SSZ-13, ion exchanged with protons and alkali-metal cations Li(+), Na(+), and K(+), were investigated using adsorption isotherms of CO(2) and N(2). The results show that Li-, Na-SSZ-13 have excellent CO(2) capacity at ambient temperature and pressure; in general, Li-SSZ-13 shows the highest capacity for N(2), CO(2) particularly in the low-pressure region. The effect of cation type and Si/Al ratio (6 and 12) on the adsorption properties was investigated through analysis of adsorption isotherms and heats of adsorption. The separation of CO(2) in a flue gas mixture was evaluated for these adsorbents in the pressure swing adsorption and vacuum pressure adsorption processes. PMID:23249267

  2. Ergot alkaloids in rye flour determined by solid phase cation-exchange and high pressure liquid chromatography with fluorescence detection

    OpenAIRE

    Storm, Ida Drejer; Have Rasmussen, Peter; Strobel, Bjarne W.; Hansen, Hans Christian Bruun

    2008-01-01

    Abstract Ergot alkaloids (EAs) are mycotoxins which are unavoidable contaminants of cereal products, particularly rye. A method was compiled employing clean-up by cation-exchange solid phase extraction, separation by high-pressure liquid chromatography under alkaline conditions and fluorescence detection. It is capable of separating and quantifying both C8-isomers of ergocornine, a-ergocryptine, ergocristine, ergonovine, and ergotamine. The average recovery was 61?10 % with limits ...

  3. Enhanced DOC removal using anion and cation ion exchange resins.

    Science.gov (United States)

    Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

    2016-01-01

    Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. PMID:26624231

  4. Preparation of Medium Cation Exchange Stationary Phase of Polymeric Matrix and Their Chromatographic Properties

    Institute of Scientific and Technical Information of China (English)

    CHEN,Gang; GONG,Bo-Lin; BAI,Quan; GENG,Xin-Du

    2007-01-01

    Based on the monodisperse poly(glycidyl methacrylate-co-ethylenedimethacrylate) beads (PGMA/EDMA) with macropore as a medium, a new hydrophilic medium cation exchange (MCX) stationary phase for HPLC was synthesized by a new chemically modified method. The stationary phase was evaluated with the property of ion exchange, separability, reproducibility, hydrophilicity, effect of salt concentration, salt types, column loading and pH on the separation and retention of proteins in detail. It was found that it follows ion exchange chromatographic (IEC)retention mechanism. The measured bioactivity recovery for lysozyme was (96±5)%. The dynamic protein loading capacity of the synthesized MCX packings was 21.8 mg/g. Five proteins were almost completely separated within 6.0 min at a flow rate of 4 mL/min using the synthesized MCX resin. The MCX resin was also used for the rapid separation and purification of lysozyme from egg white with only one step. The purity and specific bioactivity of the purified lysozyme was found more than 95% and 70345 U/mg, respectively.

  5. Chromatographic separation of inorganic ions on thin layers of titanium phosphate ion-exchanger.

    Science.gov (United States)

    Ghoulipour, Vanik; Safari, Moharram

    2014-12-01

    The chromatographic behavior of 30 inorganic cations has been studied on thin layers of titanium phosphate ion-exchanger using several aqueous, organic and mixed mobile phases. The separation of one ion from several other ions and also ternary and binary separations have been developed. Some important analytical separations are reported. The effect of pH of the mobile phase on retention factor (Rf) values of the cations in the presence of complex-forming anion along with the separation power of the ion-exchanger were studied. This ion-exchanger exhibits high sorption capacity and varying selectivity towards metal ions and makes it a suitable stationaiy phase in thin layer chromatography.

  6. Chromatographic separation of inorganic ions on thin layers of titanium phosphate ion-exchanger

    Institute of Scientific and Technical Information of China (English)

    Vanik GHOULIPOUR; Moharram SAFARI

    2014-01-01

    The chromatographic behavior of 30 inorganic cations has been studied on thin layers of titanium phosphate ion-exchanger using several aqueous,organic and mixed mobile phases. The separation of one ion from several other ions and also ternary and binary separations have been developed. Some important analytical separations are reported. The effect of pH of the mobile phase on retention factor(Rf)values of the cations in the presence of complex-forming anion along with the separation power of the ion-exchanger were studied. This ion-exchanger exhibits high sorption capacity and varying selectivity towards metal ions and makes it a suitable stationary phase in thin layer chromatography.

  7. Preparation of poly(glycidylmethacrylate-divinylbenzene) weak acid cation exchange stationary phases with succinic anhydride, phthalic anhydride, and maleic anhydride for ion chromatography.

    Science.gov (United States)

    Liu, Junwei; Wang, Yong; Wu, Shuchao; Zhang, Peimin; Zhu, Yan

    2016-08-01

    In this work, poly(glycidylmethacrylate-divinylbenzene) microspheres were prepared and applied for the preparation of weak acid cation exchange stationary phases. Succinic anhydride, phthalic anhydride, and maleic anhydride were selected as carboxylation reagents to prepare three weak acid cation exchangers by direct chemical derivatization reaction without solvent or catalyst. The diameters and dispersity of the microspheres were characterized by scanning electron microscopy; the amount of accessible epoxy groups and mechanical stability were also measured. The weak acid cation exchangers were characterized by Fourier transform infrared spectroscopy; the content of carboxyl groups was measured by traditional acid base titration method. The chromatographic properties were characterized and compared by separating alkali, alkaline earth metal ions and ammonium and polar amines. The separation properties enhanced in the order of succinic anhydride, phthalic anhydride, and maleic anhydride modified poly(glycidylmethacrylate-divinylbenzene) cation exchangers. PMID:27288092

  8. Ra/Ca separation by ion exchange chromatography

    International Nuclear Information System (INIS)

    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)

  9. CO 2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: A molecular simulation study

    KAUST Repository

    Chen, Yifei

    2012-02-28

    A molecular simulation study is reported for CO 2 adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na +, K +, Rb +, Cs +, Mg 2+, Ca 2+, and Al 3+). The isosteric heat and Henry\\'s constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ < Al 3+). At low pressures, cations act as preferential adsorption sites for CO 2 and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO 2 adsorption. Furthermore, the adsorption selectivity of CO 2/H 2 mixture increases as Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ ≈ Al 3+. At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H 2O, the selectivity decreases drastically because of the competitive adsorption between H 2O and CO 2, and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations. © 2012 American Chemical Society.

  10. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Programa Nacional de Gestion de Residuos Radiactivos, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Bianchi, Hugo L. [Gerencia de Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); ECyT, Universidad Nacional de General San Martin, Campus Miguelete, Ed. Tornavias, Martin de Irigoyen 3100, 1650 San Martin (Argentina); Conicet, Av. Rivadavia 1917, 1033 Buenos Aires (Argentina); Manzini, Alberto C. [Programa Nacional de Gestion de Residuos Radiactivos, Comision Nacional de Energia Atomica, Av. Del Libertador 8250, CP 1429, Ciudad Autonoma de Buenos Aires (Argentina)

    2012-05-15

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Ni{sup 2+} in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH{sub 4}) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 Degree-Sign C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600 Degree-Sign C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 Degree-Sign C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 Degree-Sign C reached a plateau or

  11. Radiochemical separation of gallium by amalgam exchange

    Science.gov (United States)

    Ruch, R.R.

    1969-01-01

    An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

  12. Determining the cation exchange capacity of montmorillonite by simultaneous thermal analysis method

    Science.gov (United States)

    Boeva, N. M.; Bocharnikova, Yu. I.; Belousov, P. E.; Zhigarev, V. V.

    2016-08-01

    A way of determining the cation exchange capacity of montmorillonite by simultaneous thermal analysis is developed using as an example the bentonites of the 10th Khutor deposit (Republic of Khakassia) and the Vodopadnyi area (Sakhalin Island). A correlation is established between the cation exchange capacity of smectite and its weight loss upon heating in the range of dehydration; the enthalpy of dehydration of montmorillonite; and the weight loss and the enthalpy of thermal dissociation of ethylene glycol contained in the interlayer space of the mineral's crystal structure. These data open up new possibilities for determining the cation exchange capacity of montmorillonite, the most important technological indicator of the natural clay nanomineral.

  13. Synthesis, characterization and ion exchange properties of zirconium(IV) tungstoiodophosphate, a new cation exchanger

    Indian Academy of Sciences (India)

    Weqar Ahmad Siddiqui; Shakeel Ahmad Khan

    2007-02-01

    Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable sample is prepared by adding a mixture of aqueous solutions of 0.5 mol L-1 sodium tungstate, potassium iodate and 1 mol L-1 orthophosphoric acid to aqueous solution of 0.1 mol L-1 zirconium(IV) oxychloride. Its ion exchange capacity for Na+ and K+ was found to be 2.20 and 2.35 meq g-1 dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger at different temperatures has been studied. The analytical importance of the material has been established by quantitative separation of Pb2+ from other metal ions.

  14. Aspects of the super-equivalent sorption of glycine by cation exchanger KU-2-8

    Science.gov (United States)

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

    2016-07-01

    The structure formed in a sorbent during the super-equivalent sorption of glycine by cation exchanger KU-2-8 is optimized via quantum chemical simulation. The differential thermodynamic characteristics of ion exchange and super-equivalent sorption in the studied system are calculated using a thermodynamic approach that allows us to describe the simultaneous exchange and super-equivalent sorption of compounds by ion-exchangers.

  15. An Investigation into the Effect of Cation-exchange on the Adsorption Performance of Indium-based Sodalite-ZMOF

    KAUST Repository

    Samin, Umer A.

    2016-04-13

    There is a pressing need for advanced solid-state materials that can be implemented in industrial gas separation processes to achieve separations with a significantly reduced energy input compared to what is typically required from current technologies. Although certain porous materials like zeolites bear some commercial significance for gas separation; their inherent lack of tunability limits the extent to which these materials may be exploited in industry. Zeolite-like Metal-Organic Frameworks (ZMOFs) are a sub-class of Metal-Organic Framework materials (MOFs) that show a structural semblance to zeolites while possessing the tunability advantages of MOF materials. ZMOFs which are topologically similar to certain zeolites can be functionalised and tuned in numerous ways to improve their gas separation properties. In this work, indium-based sod-ZMOF was tuned by cation-exchange and then characterised by different experimental tools such as single-crystal x-ray diffraction, elemental analysis and gas adsorption. It was found that various parameters like the choice of cation, the concentration of salt solution and the choice of solvent had a significant bearing on the cation-exchange of sod-ZMOF and its subsequent adsorption properties.

  16. Transition metal cation separations with a resorcinarene-based amino acid stationary phase.

    Science.gov (United States)

    Li, Na; Allen, Lee J; Harrison, Roger G; Lamb, John D

    2013-03-01

    A resorcinarene-based macrocyclic ligand functionalized with alanine and undecyl groups (AUA) was synthesized and applied to ion chromatographic separations. The selectivity and separation of transition metal ions on a column packed with AUA adsorbed onto 55% cross-linked styrene-divinylbenzene resin are presented. The upper and lower rims of the resorcinarene were modified with amino acids and -C(11)H(23) alkyl chains, respectively. The four carboxylic acid groups on the upper rim act as cation-exchangers while the four -C(11)H(23) alkyl chains serve to anchor the ligand to the resin surface by the hydrophobic effect. A systematic study of the effect of different eluent components including non-metal-chelating (HNO(3)) and chelating acids (oxalic acid, succinic acid, dipicolinic acid, and citric acid) on the retention of transition metal ions was investigated. Six metal ions (Mn(2+), Co(2+), Ni(2+), Cd(2+), Cu(2+), and Zn(2+)) were separated on the AUA column within a reasonable time with a single eluent gradient using oxalic acid. The separation is compared to that obtained using a commercial column containing carboxylic acid functional groups. The AUA column containing four preorganized carboxylic acid groups showed selectivity for Cu(2+) when no chelating eluent was present, a selectivity which was not observed with the comparison column.

  17. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    OpenAIRE

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange com...

  18. Ionic Liquid Synergistic Cation-Exchange System for the Selective Extraction of Lanthanum(III) Using 2-Thenoyltrifluoroacetone and 18-Crown-6

    OpenAIRE

    Hirayama, Naoki; Okamura, Hiroyuki; Kidani, Keiji; Imura, Hisanori

    2008-01-01

    A novel synergistic extraction system was investigated for the possible selective separation of light lanthanoids using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an extraction solvent and 2-thenoyltrifluoroacetone and 18-crown-6 as extractants. Trivalent lanthanum was efficiently extracted as a cationic ternary complex by the cation-exchange process, whereas europium and lutetium showed relatively low extractability without forming respective ternary ...

  19. Optimal design of the separate type heat pipe heat exchanger

    Institute of Scientific and Technical Information of China (English)

    YU Zi-tao; HU Ya-cai; CEN Ke-fa

    2005-01-01

    Separate type heat pipe heat exchangers are often used for large-scale heat exchanging. The arrangement of such a heat exchanger conveniently allows heat input to and output from the heat exchanger at remote locations. The traditional method of designing an ordinary HPHE (heat pipe heat exchanger) is commonly applied in the separate type exchanger design, but the calculations have to be carried out separately, which makes it very complicated. In this work, the ε-NTU (effectiveness-Number of Transfer Units) method was applied for optimization analysis of single- or multi-level separate type heat pipe heat exchangers. An optimizing formula for single-level separate type heat pipe heat exchangers was obtained. The optimizing principles of effectiveness-NTU and heat transfer rate by the equal distribution method for multi-level separate type heat pipe heat exchanger are presented. The design of separate type heat pipe heat exchangers by the optimizing method is more convenient and faster than by the traditional method.

  20. Behavior of cationic, anionic and colloidal species of titanium, zirconium and thorium in presence of ion exchange resins

    International Nuclear Information System (INIS)

    The distribution of titanium, zirconium and thorium is aqueous and resin phases has been studied using strong cationic resin in the R-NH4 form. Solutions of the above elements in perchloric, nitric, hydrochloric and suphuric media were used. Each set of experiments was made by separately varying one of the five parameters - type of anion present, acidity of solution, temperature of percolation, age of solution and concentration of the element. It was found that, depending on the particular balance of these parameters, the elements investigated may be found in acidic solutions either as cationic, anionic or colloidal species. It is emphasized that the colloidal species of titanium, zirconium or thorium are not retained by the ion exchangers, and from this property a method for the separation and purification of the above elements has been outlined

  1. Effect of Lanthanum Accumulation on Cation Exchange Capacity and Solution Composition of Red Soil

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Pot and adsorption-exchange experiments were carried out by collecting the soil samples from the surface layer (0~15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences, in Jiangxi Province of China. When concentration of the exogenous La3+ exceeded 400 mg kg-1, there was less non-exchangeable La3+ than exchangeable La3+ in the soil. Cation exchange capacity of the soil changed slightly with increasing concentration of the exogenous La3+ in both experiments. However, in the adsorption-exchange experiment, when concentration of the exogenous La3+ was higher than 300 mg kg-1, exchangeable basic cations decreased significantly, while exchangeable hydrogen and exchangeable aluminum increased significantly compared with the control treatments. The amounts of base cations (Ca2+, Mg2+, K+ and Na+) exchanged by La3+ in the supernatant solution increased with the concentration of the exogenous La3+, especially when concentration of the exogenous La3+ was higher than 50 mg kg-1.

  2. 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"…

  3. Prepared polymethacrylate-based monoliths for the separation of cations by non-suppressed capillary ion chromatography.

    Science.gov (United States)

    Li, Jing; Zhu, Yan

    2014-01-01

    This paper describes a novel analytical system for non-suppressed capillary ion chromatography. Methacrylate monolithic columns were prepared from silanized fused-silica capillaries of 320 µm i.d. by in situ polymerization of glycidyl methacrylate and ethylene dimethacrylate in the presence of 1,4-butanediol, 1-propanol and water as the porogen solvents. The introduction of cation-exchange sites was achieved by sulfonating the matrix with sodium sulfite to produce total cation-exchange capacities in the range of 45-105 μequiv/mL for a 25 cm column. The conditions (concentrations of sodium sulfite solution, reacting time and modified flow rate) of sulfonation were optimized. The hydrodynamic and chromatographic performances were estimated. Coupled with a conductivity detector, a capillary ion chromatography system was set up with the prepared column. Finally, the resultant column was used for the separations of five common univalent cations (Li(+), Na(+), NH4(+), K(+) and Cs(+)) using methanesulfonic acid as the eluent and four divalent cations (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) by non-suppressed capillary ion chromatography; the chromatographic parameters were further researched.

  4. Charge exchange of a polar molecule at its cation

    International Nuclear Information System (INIS)

    The Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a σ-electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particles. The resonant charge-transfer cross section is calculated, and the effect of the dipole moments of the core on the cross section is analyzed. It is shown that allowance for the dependence of the exchange potential on the orientation of the dipole moments relative to the molecular axis may change the dependence of the cross section on the velocity of colliding particles, which is typical of the resonant charge exchange, from the resonance to the quasi-resonance dependence.

  5. Synthesis and adsorption properties of the cation exchange forms of OFF-type zeolite

    Science.gov (United States)

    Gorshunova, K. K.; Travkina, O. S.; Kustov, L. M.; Kutepov, B. I.

    2016-03-01

    The possibility of the ion-exchange of Na+ and K+ cations contained in OFF-type zeolite for H+, Ni2+, Cu2+, Co2+, and La3+ cations is investigated. Chemical and phase compositions, the morphology of crystals, and the adsorption properties of synthesized samples are studied via X-ray fluorescence and X-ray diffraction analysis, IR spectroscopy, scanning electron microscopy, and adsorption measurements.

  6. Ergot alkaloids in rye flour determined by solid-phase cation-exchange and high-pressure liquid chromatography with fluorescence detection

    DEFF Research Database (Denmark)

    Storm, Ida Marie Lindhardt Drejer; Rasmussen, Peter Have; Strobel, B.W.;

    2008-01-01

    Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection...

  7. Sulfonated hydrocarbon graft architectures for cation exchange membranes

    DEFF Research Database (Denmark)

    Nielsen, Mads Møller; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    A synthetic strategy to hydrocarbon graft architectures prepared from a commercial polysulfone and aimed as ion exchange membrane material is proposed. Polystyrene is grafted from a polysulfone macroinitiator by atom transfer radical polymerization, and subsequently sulfonated with acetyl sulfate...... to various degrees. Series of grafting densities and graft lengths are prepared, and membranes are solvent cast from DMSO. The membrane properties in aqueous environments are evaluated from their water swelling behavior, and their thermal properties and stability are investigated by thermogravimetric...

  8. Sulfonation Process and Desalination Effect of Polystyrene/PVDF Semi-Interpenetrating Polymer Network Cation Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Yin-lin Lei

    2014-07-01

    Full Text Available With the classical sulfonation method of polystyrene-based strongly acidic cation exchange resins, polystyrene/polyvinylidene fluoride (PVDF alloy particles were sulfonated to obtain a cation exchange resin, which was then directly thermoformed to prepare a semi-interpenetrating polymer network (semi-IPN cation exchange membrane. The effects of the swelling agent, sulfonation time and temperature and the relative contents of polystyrene and divinylbenzene (DVB in the alloy particles on the feasibility of the membrane formation are discussed. The results indicate that a favorable sulfonation degree above 80% and a suitable ion exchange capacity of 1.5–2.4 mmol/g can be gained, with concentrated sulfuric acid as the sulfonation agent and 1,2-dichloroethane as the swelling agent. The running electrical resistance and desalination effect of the prepared cation exchange membrane were measured in a pilot-scale electrodialyser and not only obviously exceeded a commercial heterogeneous cation exchange membrane, but was also very close to a commercial homogenous membrane. In this way, the authors have combined the classical sulfonation method of polystyrene-based cation exchange resins with the traditional thermoforming manufacturing process of heterogeneous cation exchange membranes, to successfully develop a novel, low-price, but relatively high-performance polystyrene/PVDF cation exchange membrane with the semi-IPN structure.

  9. Separation of 1,3-Propanediol from Aqueous Solutions by Ion Exchange Chromatography

    Directory of Open Access Journals (Sweden)

    Rukowicz Beata

    2014-06-01

    Full Text Available 1,3-propanediol is a promising monomer with many applications and can be produced by bioconversion of renewable resources. The separation of this product from fermentation broth is a difficult task. In this work, the application of cation exchange resin for the separation of 1,3-propanediol from model aqueous solution was examined. The best effect of separation of 1,3-propanediol from glycerol using sorption method was obtained for H+ resin form, although the observed partition coefficient of 1,3-propanediol was low. On the basis of the results of the sorption of 1,3-propanediol, the ionic forms of the resin were selected and used in the next experiments (H+, Ca2+, Ag+, Na+, Pb2+, Zn2+. The best results in ion exchange chromatography were obtained for cation exchange resin in H+ and Ca2+ form. The use of smaller particle size of resin and a longer length of the column allows to obtain better separation of mixtures.

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

    Science.gov (United States)

    Cornelius, Richard

    1980-01-01

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

  11. Impact of sediment-seawater cation exchange on Himalayan chemical weathering fluxes

    Science.gov (United States)

    Lupker, Maarten; France-Lanord, Christian; Lartiges, Bruno

    2016-08-01

    Continental-scale chemical weathering budgets are commonly assessed based on the flux of dissolved elements carried by large rivers to the oceans. However, the interaction between sediments and seawater in estuaries can lead to additional cation exchange fluxes that have been very poorly constrained so far. We constrained the magnitude of cation exchange fluxes from the Ganga-Brahmaputra river system based on cation exchange capacity (CEC) measurements of riverine sediments. CEC values of sediments are variable throughout the river water column as a result of hydrological sorting of minerals with depth that control grain sizes and surface area. The average CEC of the integrated sediment load of the Ganga-Brahmaputra is estimated ca. 6.5 meq 100 g-1. The cationic charge of sediments in the river is dominated by bivalent ions Ca2+ (76 %) and Mg2+ (16 %) followed by monovalent K+ (6 %) and Na+ (2 %), and the relative proportion of these ions is constant among all samples and both rivers. Assuming a total exchange of exchangeable Ca2+ for marine Na+ yields a maximal additional Ca2+ flux of 28 × 109 mol yr-1 of calcium to the ocean, which represents an increase of ca. 6 % of the actual river dissolved Ca2+ flux. In the more likely event that only a fraction of the adsorbed riverine Ca2+ is exchanged, not only for marine Na+ but also Mg2+ and K+, estuarine cation exchange for the Ganga-Brahmaputra is responsible for an additional Ca2+ flux of 23 × 109 mol yr-1, while ca. 27 × 109 mol yr-1 of Na+, 8 × 109 mol yr-1 of Mg2+ and 4 × 109 mol yr-1 of K+ are re-absorbed in the estuaries. This represents an additional riverine Ca2+ flux to the ocean of 5 % compared to the measured dissolved flux. About 15 % of the dissolved Na+ flux, 8 % of the dissolved K+ flux and 4 % of the Mg2+ are reabsorbed by the sediments in the estuaries. The impact of estuarine sediment-seawater cation exchange appears to be limited when evaluated in the context of the long-term carbon cycle and

  12. A method for the production of weakly acidic cation exchange resins

    Science.gov (United States)

    Heller, H.; Werner, F.; Mitschker, A.; Diehl, H. V.; Schaefer, A.

    1991-12-01

    The invention relates to a nonpolluting method for the production of weakly acidic cation exchange resins by saponification of cross-linked acrylonitrile bead polymers, with an alkaline saponification agent at elevated temperature, according to which method the bead polymer and alkaline saponification agent are jointly added only at elevated temperature.

  13. Nongeminate Radiative Recombination of Free Charges in Cation-Exchanged PbS Quantum Dot Films

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Ashley R.; Beard, Matthew C.; Johnson, Justin C.

    2016-06-01

    Using photoluminescence (PL) spectroscopy we explore the radiative recombination pathways in PbS quantum dots (QDs) synthesized by two methods. We compare conventionally synthesized PbS from a PbO precursor to PbS synthesized using cation-exchange from CdS QDs. We show that strongly coupled films of PbS QDs from the cation-exchange luminesce with significant efficiency at room temperature. This is in stark contrast to conventional PbS QDs, which have exceedingly weak room temperature emission. Moreover, the power dependence of the emission is quadratic, indicating bimolecular radiative recombination that is reasonably competitive with trap-assisted recombination, a feature previously unreported in coupled PbS QD films. We interpret these results in terms of a greatly reduced defect concentration for cation-exchanged QDs that mitigates the influence of trap-assisted recombination. Cation-exchanged QDs have recently been employed in highly efficient and air-stable lead chalcogenide QD devices, and the reduced number of trap states inferred here may lead to improved current collection and higher open circuit voltage.

  14. A Simple Apparatus for Fast Ion Exchange Separations

    International Nuclear Information System (INIS)

    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

  15. Electrochemical ion exchanger in the water circuit to measure cation conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Bernt; Ingemarsson, Rolf; Settervik, Gustav [Ringhals AB, Vaeroebacka (Sweden); Velin, Anna [Vattenfall Research and Development AB, Stockholm (Sweden)

    2011-03-15

    At Ringhals Nuclear Power Plant (NPP), more than four years of successful operation with a full-scale electrode ionization (EDI) unit for the recycling of steam generator blowdown gave the inspiration to modify and scale down this EDI process. As part of this project, the possibility of replacing the cation exchanger columns used for cation conductivity analysis with some small and integrated electrochemical ion exchange cells was explored. Monitoring the cation conductivity requires the use of a small cation resin column upstream of the conductivity probe and is one of the most important analyses at power plants. However, when operating with high alkaline treatment in the steam circuit, there is the disadvantage of rapid exhaustion of the resins, necessitating frequent replacement or regeneration. This causes interruptions in the monitoring and gives rise to a high workload for the maintenance staff. This paper reports on the optimization and testing of two different two-compartment electrochemical cells for possible replacement of the cation resin columns for analyzing cation conductivity in the secondary steam circuit at Ringhals NPP. Field tests during start-up conditions and more than four months of steady operation together with real and simulated tests for impurity influences indicate that an electrical ion exchange (ELIX) process could be successfully used to replace the resin columns in Ringhals while operating with high-pH all-volatile treatment (AVT) using hydrazine and ammonia. Installation of an ELIX system downstream of a particle filter and upstream of a small cation resin column will introduce additional safety and further reduce the maintenance and possible interruptions. Performance of the ELIX process together with other chemical additives (morpholine, ethanolamine, 3-methoxypropylamine, dimethylamine) and dispersants may be further evaluated to qualify the ELIX process as well as steam generator blowdown electrodeionization for wider use in

  16. Chemical exchange equilibria in isotope separation. Part I : Evaluation of separation factors

    International Nuclear Information System (INIS)

    The theory of chemical exchange equilibria as applied to the isotope separation processes and the isotope effects on equilibrium constants of different exchange reactions has come a long way since its inception by Urey and Rittenberg. An attempt has been made to bring relevant information together and present a unified approach to isotopic chemical exchange equilibrium constant evaluation and its implications to separation processes. (auth.)

  17. Exchangeable Cations in the Soils of Quercus Dominated Forests in Northeastern Austria

    Science.gov (United States)

    Yan, Shuai; Bruckman, Viktor J.; Glatzel, Gerhard

    2010-05-01

    In northeastern Austria there is a growing interest in increased utilisation of forest biomass for energy. This study focuses on soil properties and nutrient pool characteristics in deciduous forests in order to provide advice for forest management. We (i) quantified selected exchangeable cations in the soils of our study area and (ii) identified the effects of stand age, soil type, soil depth and soil pH on exchangeable cations and cation exchange capacity (CEC). Nine permanent Quercus petraea dominated plots on sandy, clayey cambisols and calcic chernozem were selected for our study. From each plot 18 soil samples were collected in a systematic grid by means of a soil corer with 70 mm diameter to a maximum depth of 60 cm. Soil pH, exchangeable mineral elements K, Ca, Mg, Na, Mn, Al, and Fe were determined in five geometric soil horizons. Statistical analysis showed that (i) forest age did not influence the exchangeable K content of the sandy soils; (ii) the exchangeable K content decreased with increasing stand age in clayey cambisols; (iii) exchangeable K, Na and Mg were higher in calcic chernozems and clayey cambisols (iv) exchangeable Fe was significantly higher in sandy forest soils except in the 60-80 years old stand; (v) exchangeable Fe was below detection limit in calcic chernozem soils. A comparison of exchangeable cations revealed that (i) Ca is the key element of base cations (ii) the content of base cations is strongly significantly higher in calcic chernozem soils (iii) calcic chernozem soils have the highest CEC. CEC ranged from 38 to 190 μmol/g in the entire research area. Base cations, acid cations and CEC differ with soil depth as followed (i) in sandy and clayey cambisols, CEC had a minimum in 20 cm depth and then increased with soil depth to 50 cm; (ii) CEC decreased steadily with soil depth in calcic chernozems. As expected, CEC is significantly positively correlated (Pearson correlation coefficient 0.661, Pground biomass nutrients, the rate

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

    Science.gov (United States)

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

    2000-01-01

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

  19. Comparison of Phosphoproteomic Separation Strategies Based on Strong Cation Exchange Chromatography-Isoelectric Focusing Techniques%基于强阳离子交换色谱与等电聚焦的磷酸化蛋白质组学分离策略比较

    Institute of Scientific and Technical Information of China (English)

    隋少卉; 董俊军; 王京兰; 蔡耘; 钱小红

    2012-01-01

    Efficient pre-purification steps for the enrichment of phosphorylated proteins or phos-phopeptides are necessary for better detection of phosphorylation sites in phosphoproteomic analysis. Currently, the most common first-dimensional separation technique used is strong cation exchange (SCX). A potential alternative to SCX-based separation is to use isoelectric focusing (IEF) as a first-dimensional separation technique, which has been demonstrated recently. In this study, we present a direct comparison between SCX and IEF based on IPG strips (IPG-IEF) for the phosphoproteomic separation. The comparison experiments discussed in this study utilized standard phosphoproteins and a real sample of HepG2 cell. Then the comparison of 18O labeling phosphopeptides' stability under immobilized pH gradient gel (IPG)-IEF with under SCX was made. Fractions from both technique (SCX and IPG-IEF) were analyzed using the High Mass Accuracy LTQ-FTICR-MS/MS. The results demonstrate that SCX-LTQ-FT and IPG-IEF-LTQ-FT are useful in the phosphopeptides enrichment analysis on a large scale. And SCX-LTQ-FT is relative superior to IPG-IEF-LTQ-FT, whereas the 18 O labeling phosphopeptides'stability under SCX-LTQ-FT is relatively poor with that under IPG-IEF-LTQ-FT.%比较分析了强阳离子交换(SCX)与等电聚焦(IPG-IEF)技术在磷酸化蛋白质组学中的应用.采用3种标准磷酸化蛋白对SCX与IPG-IEF两种技术对磷酸化肽段富集的有效性进行考察.以HepG2细胞为复杂样本,考察SCX与IPG-IEF在实际样本中的应用情况.对SCX与IPG-IEF技术在18O标记的磷酸化蛋白质组定量研究中的应用情况进行考察.蛋白鉴定采用高准确度、高灵敏度、高分辨率的LTQ-FTICR-MS/MS质谱仪.实验表明:SCX和IPG- IEF在大规模磷酸化肽段分离过程中均有效;在复杂样本中,SCX技术的分离效果优于IPG- IEF; IPG- IEF的重复性好于SCX;在磷酸化蛋白质组定量分析结果表明,IPG-IEF技术的稳定性优

  20. Boron Separation by the Two-step Ion-Exchange for the Isotopic Measurement of Boron

    Institute of Scientific and Technical Information of China (English)

    WANG,Qing-Zhong(王庆忠); XIAO,Ying-Kai(肖应凯); WANG,Yun-Hui(王蕴惠); ZHANG,Chong-Geng(张崇耿); WEI,Hai-Zhen(魏海珍)

    2002-01-01

    An improved procedure for extraction and purification of boron from natural samples is presented. The separation and purification of boron was carried out using a boron-specific resin, Amberlite IRA743, and a mixed ion exchange resin,Dowex 50W × 8 and Ion Exchanger Ⅱ resin. Using the mixed ion exchange resin which adsorbs all cations and anions except boron, the HCl and other cations and anions left in eluant from the Amberlite IRA 743 were removed effectively. In this case, boron loss can be avoided because the boron-bearing solution does not have to be evaporated to reach dryness to dislodge HCl. The boron recovery ranged from 97.6% to 102% in this study. The isotopic fractionation of boron can be negligible within the precision of the isotopic measurement. The results show that boron separation for the isotopic measurement by using both Amberlite IRA 743 resin and the mixed rein is more effective than that using Amberlite IRA 743 resin alone. The boron in samples of brine, seawater, rock, coral and foraminifer were separated by this procedure. Boron isotopic compositions of these samples were measured by thermal ionization mass spectrometry in this study.

  1. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

    Science.gov (United States)

    Tu, Renyong; Xie, Yi; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; Trizio, Luca De; Manna, Liberato

    2016-06-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd(2+) or Hg(2+), yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd(2+) and Hg(2+) ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2-xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb(2+) or Sn(2+), yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2-xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum.

  2. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

    Science.gov (United States)

    Tu, Renyong; Xie, Yi; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; Trizio, Luca De; Manna, Liberato

    2016-06-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd(2+) or Hg(2+), yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd(2+) and Hg(2+) ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2-xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb(2+) or Sn(2+), yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2-xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum. PMID:27177274

  3. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals

    CERN Document Server

    Tu, Renyong; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; De Trizio, Luca; Manna, Liberato

    2016-01-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e. with coordination number 4), such as Cd2+ or Hg2+, yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd2+ and Hg2+ ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2- xTe particles could be more easily deformed to match the anion framework of t...

  4. Principles of separation: indications and therapeutic targets for plasma exchange.

    Science.gov (United States)

    Williams, Mark E; Balogun, Rasheed A

    2014-01-01

    Extracorporeal "blood purification," mainly in the form of hemodialysis has been a major portion of the clinical activity of many nephrologists for the past 5 decades. A possibly older procedure, therapeutic plasma exchange, separates and then removes plasma as a method of removing pathogenic material from the patient. In contrast to hemodialysis, therapeutic plasma exchange preferentially removes biologic substances of high molecular weight such as autoantibodies or alloantibodies, antigen-antibody complexes, and Ig paraproteins. These molecular targets may be cleared through two alternative procedures: centrifugal separation and membrane separation. This review presents operational features of each procedure, with relevance to the nephrologist. Kinetics of removal of these plasma constituents are based on the principles of separation by the apheresis technique and by features specific to each molecular target, including their production and compartmentalization in the body. Molecular targets for common renal conditions requiring therapeutic plasma exchange are also discussed in detail.

  5. Effect of quinidine on cation exchange in cultured cells.

    Science.gov (United States)

    McCall, D

    1976-06-01

    The effects of quinidine on membrane ion exchange were examined using monolayer cultures of mammalian cells. Quinidine, in concentrations from 10(-6) to 10(-3) M, produced a prompt inhibition of the passive Na influx, dose-dependent along a sigmoid log dose-response curve. This effect was at a maximum for each concentration of the drug within 30 seconds of application. Passive Na influx (pmol/cm2/sec) decreased from 18.8 to 17.6 (P less than .05) and 10.5 (P less than .001) in the presence of 10(-6) and 10(-3) M quinidine, respectively. In the continued presence of quinidine, there was no further time-dependent effect on the Na influx, nor was there any tendency for the influx to recover. Washing the cells free of quinidine, however, resulted in a return of Na influx to control levels within 1 to 3 minutes. After 1 to 2 minute of quinidine treatment, coupled active Na efflux/K influx rapidly declined, reaching minimum values for each concentration between 2 to 4 minutes of drug treatment. Beyond that time, active Na/K fluxes again increased, but to values which remained significantly less than control, for up to 4 hours. Ten minutes of exposure to quinidine were required before any demonstrable effect on the passive K efflux could be recorded. In the presence of quinidine, there was reduced membrane turnover of both Na and K, but such that after a brief initial period (10 minutes or less) both ions were in flux equilibrium, explaining the absence of change in [Nai] and [Ki] in the presence of quinidine. Calculations of Ec1 indicated that, when present for 4 hours, quinidine did not change the Em in these cells although significant (P less than .001) reductions in apparent PNa and Pk values were recorded. The effect on PNa was much greater than that on Pk. The quinidine-induced flux changes occurred in a definite temporal sequence suggesting that they could all be explained on the basis of one direct initial action. This initial direct action, namely the prompt

  6. Determination of organoarsenic species in marine samples using gradient elution cation exchange HPLC-ICP-MS

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt; Julshamn, Kåre

    2003-01-01

    A method for the determination of arsenic species in marine samples using high performance liquid chromatography coupled to inductively coupled mass spectrometry (HPLC-ICP-MS) has been developed. Cation exchange HPLC with gradient elution using pyridine formate as the mobile phase was employed...... and dimethylarsinoylacetic acid, whereas the cationic arsenocholine ion and tetramethylarsonium ion were not affected. The accuracy of the method for DMA, AsB and TMAs was validated with the CRMs DORM-2 and BCR626 Tuna. The concentrations found for arsenobetaine, dimethylarsinic acid and tetramethylarsonium ion were within...

  7. Electronic phase separation in the pyrochlore double-exchange model

    OpenAIRE

    Motome, Yukitoshi; Furukawa, Nobuo

    2010-01-01

    Electronic phase separation and related inhomogeneity is ubiquitously seen in strongly-correlated systems. A typical example is found between ferromagnetic metal and antiferromagnetic insulator in CMR manganese oxides. Here we demonstrate that the geometrical frustration brings distinctive aspects into the phase separation phenomena. From Monte Carlo simulation and a simple energy comparison for the pyrochlore double-exchange model, we show that such phase separation takes place between ferro...

  8. Advances in boron-10 isotope separation by chemical exchange distillation

    Energy Technology Data Exchange (ETDEWEB)

    Song Shuang, E-mail: chengruoyu2@sina.co [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Mu Yujun; Li Xiaofeng; Bai Peng [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2010-01-15

    Advances in boron-10 isotope separation by chemical exchange distillation are reviewed in this article. With a brief introduction of the principle of the separation, the progress on the research of this method and the problems relating to the separation coefficient are discussed. Several new donors, including nitromethane, acetone, methyl isobutyl ketone (MIBK) and diisobutyl ketone (DIBK), which have large separation factors are introduced. The complexes of these new donors and boron trifluoride (BF{sub 3}) are more stable than those of using the donors examined before. Among these new donors nitromethane could be a promising substitute for donors in present use to develop new technology of separating boron-10.

  9. Exchange of interlayer cations in micaceous minerals. Progress report, August 1, 1974--July 31, 1975

    International Nuclear Information System (INIS)

    Information pertaining to the sorption and exchange of interlayer cations in micaceous minerals was developed along several lines. Cs sorption experiments with different minerals and particle sizes established the periods required for maximum sorption at different temperatures and downgraded the impact anticipated from a contraction of particle edges by Cs. Added interlayer Cs in even highly charged minerals (degraded muscovite) proved to be very exchangeable in air-dry, clay size particles. Heat treatments greatly retarded the exchange of this sorbed Cs and by doing so have circumvented the commonly observed small particle effects. Structural Fe in micas was shown to be susceptible to oxidation by various Br2 treatments but these treatments also removed a lot of K that must be accounted for in a determination of changes in interlayer K exchangeability. Changes in the rate of interlayer K exchange were induced in some micaceous minerals by adding H2O2 but not in others. Specific effects of heat treatments on dioctahedral and trioctahedral micas were examined in great detail. Interlayer cation exchange experiments with different concentrations of Na and Al have produced predictable results. (U.S.)

  10. Selective separation of actinyl(V,VI) cations from aqueous solutions by Chelex-100

    Energy Technology Data Exchange (ETDEWEB)

    Kiliari, T.; Pashalidis, I. [Cyprus Univ., Nicosia (Cyprus). Chemistry Dept.

    2012-07-01

    Experimental studies on the selectivity of Chelex-100 resin for the separation of actinide cations at different oxidation states (III, IV, V and VI) from aqueous solution have shown that Chelex-100 presents increased selectivity for actinyl cations at near neutral pH (pH {proportional_to} 4.5). The effect of salinity on the chemical recovery indicates that the increased selectivity could be attributed to the formation of complexes with specific interactions and the pH area, in which the formation of the respective complexes is favored, indicates the occurrence of guest-host interactions. The specific interaction of Chelex-100 with actinyl cations could be of particular interest not only for the separation and preconcentration of uranium from natural waters prior its analysis but also for the recovery of uranium from seawater on a large scale. (orig.)

  11. Radial variations in cation exchange capacity and base saturation rate in the wood of pedunculate oak and European beech

    Energy Technology Data Exchange (ETDEWEB)

    Herbauts, J.; Penninckx, V.; Gruber, W.; Meerts, P. [Universite Libre de Bruxelles, Laboratoire de genetique et d' ecologie vegetales, Brussels (Belgium)

    2002-10-01

    Visual observation of pedunculate oak trees and European beech trees in a mixed forest stand in the Belgian Ardennes revealed decreasing cation concentration profiles in wood. In order to determine whether these profiles are attributable to endogenous factors or to decreased availability of cations in the soil, radial profiles of water-soluble, exchangeable and total cations were investigated. Cation exchange capacity of wood was also determined. Results showed wood cation exchange capacity to decrease from pith to bark in European beech and from pith to outer heartwood in pedunculate oak. Decreasing profiles of exchangeable calcium and magnesium in peduncular oak and exchangeable calcium in European beech were found to be strongly constrained by cation exchange capacity, and thus not related to environmental change. Base cation saturation rate showed no consistent radial change in either species. It was concluded that the results did not provide convincing evidence to attribute the decrease in divalent cation concentration in pedunculate oak and European beech in this location to be due to atmospheric pollution. 42 refs., 1 tab., 4 figs.

  12. Gift exchange and the separation of ownership and control

    OpenAIRE

    Maximiano, S.; Sloof, R.; Sonnemans, J.

    2013-01-01

    Numerous gift exchange experiments have found a positive relationship between employers' wage offers and workers' effort levels. In (almost) all these experiments the employer both owns and controls the firm. Yet in reality many firms are characterized by the separation of ownership and control. In this paper we explore to what extent this affects the wage-effort relationship observed. We compare the standard bilateral gift exchange game between an owner-manager and a worker with two trilater...

  13. Multicolour synthesis in lanthanide-doped nanocrystals through cation exchange in water

    KAUST Repository

    Han, Sanyang

    2016-10-04

    Meeting the high demand for lanthanide-doped luminescent nanocrystals across a broad range of fields hinges upon the development of a robust synthetic protocol that provides rapid, just-in-time nanocrystal preparation. However, to date, almost all lanthanide-doped luminescent nanomaterials have relied on direct synthesis requiring stringent controls over crystal nucleation and growth at elevated temperatures. Here we demonstrate the use of a cation exchange strategy for expeditiously accessing large classes of such nanocrystals. By combining the process of cation exchange with energy migration, the luminescence properties of the nanocrystals can be easily tuned while preserving the size, morphology and crystal phase of the initial nanocrystal template. This post-synthesis strategy enables us to achieve upconversion luminescence in Ce3+ and Mn2+-activated hexagonal-phased nanocrystals, opening a gateway towards applications ranging from chemical sensing to anti-counterfeiting.

  14. Effect of Simulated N Deposition on Soil Exchangeable Cations in Three Forest Types of Subtropical China

    Institute of Scientific and Technical Information of China (English)

    LU Xian-Kai; MO Jiang-Ming; P.GUNDERSERN; ZHU Wei-Xing; ZHOU Guo-Yi; LI De-Jun; ZHANG Xu

    2009-01-01

    The effects of simulated nitrogen (N) deposition on soil exchangeable cations were studied in three forest types of subtropical China.Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest):control (0 kg N ha-1 year-1),low N (50 kg N ha-1 year-1),medium N (100 kg N ha-1 year-1) and high N (150 kg N ha-1 ycar-1),and only three treatments (i.e.,control,low N,medium N) were established for the pine and mixed forests.Nitrogen had been applied continuously for 26 months before the measurement.The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests,and exhibited some significant negative symptoms,e.g.,soil acidification,Al mobilization and leaching of base cations from soil.The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations.Response of soil exchangeable cations to N deposition varied in the forests of subtropical China,depending on soil N status and land-nse history.

  15. Solubility and cation exchange in phosphate rock and saturated clinoptilolite mixtures

    Science.gov (United States)

    Allen, E. R.; Hossner, L. R.; Ming, D. W.; Henninger, D. L.

    1993-01-01

    Mixtures of zeolite and phosphate rock (PR) have the potential to provide slow-release fertilization of plants in synthetic soils by dissolution and ion-exchange reactions. This study was conducted to examine solubility and cation-exchange relationships in mixtures of PR and NH4- and K-saturated clinoptilolite (Cp). Batch-equilibration experiments were designed to investigate the effect of PR source, the proportion of exchangeable K and NH4, and the Cp to PR ratio on solution N, P, K, and Ca concentrations. The dissolution and cation-exchange reactions that occurred after mixing NH4- and K-saturated Cp with PR increased the solubility of the PR and simultaneously released NH4 and K into solution. The more reactive North Carolina (NC) PR rendered higher solution concentrations of NH4 and K when mixed with Cp than did Tennessee (TN) PR. Solution P concentrations for the Cp-NC PR mixture and the Cp-TN PR mixture were similar. Solution concentrations of N, P, K, and Ca and the ratios of these nutrients in solution varied predictably with the type of PR, the Cp/PR ratio, and the proportions of exchangeable K and NH4 on the Cp. Our research indicated that slow-release fertilization using Cp/PR media may provide adequate levels of N, P, and K to support plant growth. Solution Ca concentrations were lower than optimum for plant growth.

  16. Mobilization of Roadside Soil Cation Pools by Exchange with Road Deicers

    Science.gov (United States)

    Rossi, R.; Bain, D.

    2014-12-01

    Over the past sixty years, road deicers (i.e., road salt) have been applied to roadways in high latitudes to improve traffic conditions in winter weather. However, the dissolution of road deicers in highway runoff create waters with high total dissolved solids (TDS), specifically high concentrations of sodium, which can mobilize soil metals via soil cation exchange reactions. While several studies have detailed the interactions of high TDS solutions and surface and ground waters, limited attention is paid to the impacts of high TDS solutions on near-road soils. Between 2013 and 2014, soil water samples were collected from a roadside transect of lysimeter nests in Pittsburgh, PA. Soil water samples were analyzed for metal concentrations and resulting data used to examine cation dynamics. Patterns in soil water calcium and magnesium concentrations follow patterns in soil water sodium concentrations. In our samples, the highest major cation concentrations are found at the deepest lysimeters, suggesting major cations are mobilized to, and potentially accumulate in, deeper soil horizons. Concentration peaks in the downslope soil waters lag concentration peaks at the near-road nest by two months, indicating that road salt plumes persist and migrate following the road salting season. Characterizing the interactions of high TDS solutions and roadside soil cation pools clarifies our understanding of metal dynamics in the roadside environment. A deeper understanding of these processes is necessary to effectively restore and manage watersheds as high TDS solutions (i.e., road deicing, hydraulic fracturing, and marginal irrigation water) increasingly influence ecosystem function.

  17. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  18. Cation exchange on the nanoscale: an emerging technique for new material synthesis, device fabrication, and chemical sensing.

    Science.gov (United States)

    Rivest, Jessy B; Jain, Prashant K

    2013-01-01

    Cation exchange is an age-old technique for the chemical conversion of liquids or extended solids by place-exchanging the cations in an ionic material with a different set of cations. The technique is undergoing a major revival with the advent of high-quality nanocrystals: researchers are now able to overcome the limitations in bulk systems and fully exploit cation exchange for materials synthesis and discovery via rapid, low-temperature transformations in the solid state. In this tutorial review, we discuss cation exchange as a promising materials synthesis and discovery tool. Exchange on the nanoscale exhibits some unique attributes: rapid kinetics at room temperature (orders of magnitude faster than in the bulk) and the tuning of reactivity via control of nanocrystal size, shape, and surface faceting. These features make cation exchange a convenient tool for accessing nanocrystal compositions and morphologies for which conventional synthesis may not be established. A simple exchange reaction allows extension of nanochemistry to a larger part of the periodic table, beyond the typical gamut of II-VI, IV-VI, and III-V materials. Cation exchange transformations in nanocrystals can be topotactic and size- and shape-conserving, allowing nanocrystals synthesized by conventional methods to be used as templates for production of compositionally novel, multicomponent, or doped nanocrystals. Since phases and compositions resulting from an exchange reaction can be kinetically controlled, rather than governed by the phase diagram, nanocrystals of metastable and hitherto inaccessible compositions are attainable. Outside of materials synthesis, applications for cation exchange exist in water purification, chemical staining, and sensing. Since nanoscale cation exchange occurs rapidly at room temperature, it can be integrated with sensitive environments such as those in biological systems. Cation exchange is already allowing access to a variety of new materials and processes

  19. Probing the Complementarity of FAIMS and Strong Cation Exchange Chromatography in Shotgun Proteomics

    Science.gov (United States)

    Creese, Andrew J.; Shimwell, Neil J.; Larkins, Katherine P. B.; Heath, John K.; Cooper, Helen J.

    2013-03-01

    High field asymmetric waveform ion mobility spectrometry (FAIMS), also known as differential ion mobility spectrometry, coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) offers benefits for the analysis of complex proteomics samples. Advantages include increased dynamic range, increased signal-to-noise, and reduced interference from ions of similar m/ z. FAIMS also separates isomers and positional variants. An alternative, and more established, method of reducing sample complexity is prefractionation by use of strong cation exchange chromatography. Here, we have compared SCX-LC-MS/MS with LC-FAIMS-MS/MS for the identification of peptides and proteins from whole cell lysates from the breast carcinoma SUM52 cell line. Two FAIMS approaches are considered: (1) multiple compensation voltages within a single LC-MS/MS analysis (internal stepping) and (2) repeat LC-MS/MS analyses at different and fixed compensation voltages (external stepping). We also consider the consequence of the fragmentation method (electron transfer dissociation or collision-induced dissociation) on the workflow performance. The external stepping approach resulted in a greater number of protein and peptide identifications than the internal stepping approach for both ETD and CID MS/MS, suggesting that this should be the method of choice for FAIMS proteomics experiments. The overlap in protein identifications from the SCX method and the external FAIMS method was ~25 % for both ETD and CID, and for peptides was less than 20 %. The lack of overlap between FAIMS and SCX highlights the complementarity of the two techniques. Charge state analysis of the peptide assignments showed that the FAIMS approach identified a much greater proportion of triply-charged ions.

  20. A new cation-exchange method for accurate field speciation of hexavalent chromium

    Science.gov (United States)

    Ball, J.W.; McCleskey, R.B.

    2003-01-01

    A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 ??g 1-1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg 1-1 and Fe(III) concentrations up to 10 mg 1-1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

  1. Synthesis and characterization of a new inorganic cation-exchanger-Zr(IV) tungstomolybdate: Analytical applications for metal content determination in real sample and synthetic mixture

    International Nuclear Information System (INIS)

    An amorphous sample of inorganic cation-exchanger Zr(IV) tungstomolybdate was prepared by mixing varying ratios of 0.1 M aqueous solution of sodium tungstate and 0.1 M aqueous solution of sodium molybdate into 0.1 M aqueous solution of zirconium oxychloride at pH 1. This cation-exchanger was found to have a good ion-exchange capacity (2.40 mequiv. g-1 for Na+), high thermal and chemical stability. A tentative structural formula was proposed on the basis of chemical composition, FTIR and thermogravimetric analysis. Distribution coefficients (K d) values of metal ions in various solvent systems were determined. Some important and analytically difficult quantitative binary separations viz. Ni(II)-Pb(II), Ni(II)-Zn(II), Ni(II)-Cd(II), Mg(II)-Al(III), etc. were achieved. The practical applicability of the cation-exchanger was demonstrated in the separation of Cu(II)-Zn(II) from a synthetic mixture as well as from real samples of pharmaceutical formulation and brass alloy

  2. CATION-EXCHANGE MEMBRANES WITH POLYANILINE SURFACE LAYER FOR WATER TREATMENT

    Directory of Open Access Journals (Sweden)

    Dinar Dilshatovich Fazullin

    2014-01-01

    Full Text Available Ion-exchange membranes are widely used in modern technologies, particularly in the field of water treatment and make it possible to considerably reduce expenses for wastewater treatment and ensure high degree of purification. Currently, perfluorinated sulfated proton-conducting membranes are often used, such as NAFION and its Russian analogue, MF-4SK based on co-polymerization product of a perfluorinated vinyl ether with tetrafluoroethylene. However, with development of the industry, materials with improved properties and lower cost are required. The aim is to obtain ion-exchange membranes for water treatment from metal ions and to study physico-chemical properties of obtained membranes. In this study, cation exchange composite membranes with modified polyaniline surface layer on nylon and PTFE substrate have been obtained. Changes in the structure of membranes were recorded using a microscope. Throughput capacity of the membranes was determined by passing a certain volume of distilled water through the membrane. The experiment intended to determine electivity of membranes was performed by passing a certain volume of metal salt solutions of a known concentration, after which the filtrate was collected. Concentrations of the studied metal ions in the original solution and in the filtrate were determined by the method of atomic adsorptive spectrometry with electro thermal atomization "Quantum Z.ETA". Prepared highly selective ion exchange membranes. Properties of modified membranes, such as selective permeability and ion-exchange capacity have been determined. The membranes feature high selectivity for heavy metal ions. Moisture-retaining power and swelling ability of the membranes have been studied. Selectivity of the membrane to heavy metal ions is between 70 and 99%. Ion-exchange capacity of the obtained nylon polyaniline membrane is not inferior to some commercially available cation-exchange membranes. Use of the modified membranes in the

  3. Gift exchange and the separation of ownership and control

    NARCIS (Netherlands)

    S. Maximiano; R. Sloof; J. Sonnemans

    2006-01-01

    Numerous gift exchange experiments have found a positive relationship between employers' wage offers and workers' effort levels. In (almost) all these experiments the employer both owns and controls the firm. Yet in reality many firms are characterized by the separation of ownership and control. In

  4. Gift exchange and the separation of ownership and control

    NARCIS (Netherlands)

    S. Maximiano; R. Sloof; J. Sonnemans

    2013-01-01

    Numerous gift-exchange experiments have found a positive wage-effort relationship. In (almost) all these experiments the employer both owns and controls the firm. This paper explores to what extent the separation of ownership and control affects the wage-effort relationship. We compare the standard

  5. Preliminary studies of the total cation exchange capacity of sediments from two North Atlantic study sites

    International Nuclear Information System (INIS)

    Initially four different methods of measuring total cation exchange capacity were compared. There were two chemical methods (ammonium saturation with displacement into seawater, and barium saturation followed by replacement with magnesium) and two radiochemical methods (sodium-22 and caesium-134 saturation). The barium-magnesium and sodium-22 methods were then applied to sediment samples from Core D10164Pound1K from the Nares Fracture Valley, and Core D10554Pound11K from the eastern flank of the Great Meteor Rise. The material at site 10164 is a pelagic clay whereas at site 10554 it is carbonate ooze. The total cation exchange capacities (T.C.E.C.) of samples from the two sites are similar when measured by the sodium-22 method, the mean for Core 10164 was 21.7 meq/100g and 24.4 meq/100g for Core 10554. However for Core 10554 the barium-magnesium method gives a mean of 42.8 meq/100g. The difference in T.C.E.C. measured by the two methods appears to be due to the high calcite content of core 10554 sediment. Measured exchange capacities are lower than in coastal sediments. In deep sea sediments organic matter either makes a very small contribution to the T.C.E.C. (core 10164) or actually blocks exchange sites (Core 10554). Amorphous oxides of iron and manganese contribute between 20 and 50% of the T.C.E.C. (author)

  6. Separation of Ra/Ca by ion exchange

    International Nuclear Information System (INIS)

    The radium and the calcium belong to the same group in the periodic classification and as consequence both they present very similar chemical properties, that makes difficult its separation. Both elements are also frequently associate in the nature, the calcium is very abundant, the radium is not it and for that reason it is indispensable its separation to analyze to this last one. The alpha spectroscopy is very appropriate to analyze to the 226 Ra, however to achieve a good resolution of the spectra, the samples should contain small quantities of calcium. The purposes of this work were to know the chromatographic behavior of the alkaline-earthy cations: calcium, barium and radium and to apply these knowledge to the separation of the 226 Ra and its analysis by means of alpha spectroscopy. (Author)

  7. Preparation of a Cation Exchanger from Cork Waste: Thermodynamic Study of the Ion Exchange Processes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An ion exchanger was prepared by sulfonation of cork-waste chars. The exchange properties of the resultant materialwere characterized using Na+, Ca2+ or Fe3+ aqueous solutions, The content of metal ions in the solutions weredetermined by atomic absorption spectrometry. On the basis of the results obtained, the chemical equilibrium andits thermodynamic aspects related to the ion exchange process were studied. It was found that equilibrium constantK varies by the order: Na+<Ca2+<Fe3+, its value increasing with increasing temperature, and that △H°>0 and△S°>0, with -△G° following the sequence: Ca2+>Na+>Fe3+,

  8. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2012-07-01

    Full Text Available Direct borohydride fuel cells (DBFC, which operate on sodium borohydride (NaBH4 as the fuel, and hydrogen peroxide (H2O2 as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S and a cation-exchange membrane (CMI-7000S, are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  9. Chabazite: stable cation-exchanger in hyper alkaline concrete pore water.

    Science.gov (United States)

    Van Tendeloo, Leen; Wangermez, Wauter; Kurttepeli, Mert; de Blochouse, Benny; Bals, Sara; Van Tendeloo, Gustaaf; Martens, Johan A; Maes, André; Kirschhock, Christine E A; Breynaert, Eric

    2015-02-17

    To avoid impact on the environment, facilities for permanent disposal of hazardous waste adopt multibarrier design schemes. As the primary barrier very often consists of cement-based materials, two distinct aspects are essential for the selection of suitable complementary barriers: (1) selective sorption of the contaminants in the repository and (2) long-term chemical stability in hyperalkaline concrete-derived media. A multidisciplinary approach combining experimental strategies from environmental chemistry and materials science is therefore essential to provide a reliable assessment of potential candidate materials. Chabazite is typically synthesized in 1 M KOH solutions but also crystallizes in simulated young cement pore water, a pH 13 aqueous solution mainly containing K(+) and Na(+) cations. Its formation and stability in this medium was evaluated as a function of temperature (60 and 85 °C) over a timeframe of more than 2 years and was also asessed from a mechanistic point of view. Chabazite demonstrates excellent cation-exchange properties in simulated young cement pore water. Comparison of its Cs(+) cation exchange properties at pH 8 and pH 13 unexpectedly demonstrated an increase of the KD with increasing pH. The combined results identify chabazite as a valid candidate for inclusion in engineered barriers for concrete-based waste disposal.

  10. Strongly reduced band gap in NiMn2O4 due to cation exchange

    International Nuclear Information System (INIS)

    NiMn2O4 is extensively used as a basis material for temperature sensors due to its negative temperature coefficient of resistance (NTCR), which is commonly attributed to the hopping mechanism involving coexisting octahedral-site Mn4+ and Mn3+. Using density-functional theory + Hubbard U calculations, we identify a ferrimagnetic inverse spinel phase as the collinear ground state of NiMn2O4. By a 12.5% cation exchange, a mixed phase with slightly higher energy can be constructed, accompanied by the formation of an impurity-like band in the original 1 eV band gap. This impurity-like band reduces the gap to 0.35 eV, suggesting a possible source of NTCR. - Highlights: • Density functional based calculations were used to study collinear phase of NiMn2O4. • The ground-state structure is a ferrimagnetic inverse spinel phase. • The tetrahedral and octahedral Mn cations have ferromagnetic interactions. • A 12.5% cation exchange introduces an impurity-like band in the original 1 eV gap. • The 0.35 eV gap suggests a source of negative temperature coefficient of resistance

  11. Reverse flotation separation on diaspore and kaolinite in the presence of cationic polyacrylamide polymers

    Institute of Scientific and Technical Information of China (English)

    刘广义; 钟宏; 卢毅屏; 冯其明

    2003-01-01

    Based on the analyses of crystal structures and surface properties of diaspore and kaolinite, an effective diaspore depressant, CPAM(cationic polyacrylamide) polymers was discovered by single minerals tests, separation experiments of artificial mixed minerals, zetapotential and adsorption measurement. The reverse flotation separation on diaspore and kaolinite can be carried out using collector dodecylamine acetate and depressant CPAM under pH 5.5-8.5. On the surfaces of diaspore, there are a large amount of active aluminum atoms. They can bond with-C(O)NH2 groups in CPAM and make the-CH2N+(CH3)3 groups in CPAM orient toward the outer surfaces of diaspore, which prevents a majority of the dodecylamine cations from adsorbing on diaspore, enhances hydrophilicity of diaspore, and depresses the floatability of diaspore. But for kaolinite, CPAM polymers have little effect on its floatability.

  12. Emerging roles of alkali cation/proton exchangers in organellar homeostasis

    Science.gov (United States)

    Orlowski, John; Grinstein, Sergio

    2016-01-01

    The regulated movement of monovalent cations such as H+, Li+, Na+ and K+ across biological membranes influences a myriad of cellular processes and is fundamental to all living organisms. This is accomplished by a multiplicity of ion channels, pumps and transporters. Our insight into their molecular, cellular and physiological diversity has increased greatly in the past few years with the advent of genome sequencing, genetic manipulation and sophisticated imaging techniques. One of the revelations from these studies is the emergence of novel alkali cation/protons exchangers that are present in endomembranes, where they function to regulate not only intraorganellar pH but also vesicular biogenesis, trafficking and other aspects of cellular homeostasis. PMID:17646094

  13. Reducing the Cation Exchange Capacity of Lithium Clay to Form Better Dispersed Polymer-Clay Nanocomposites

    Science.gov (United States)

    Liang, Maggie

    2004-01-01

    Polymer-clay nanocomposites have exhibited superior strength and thermo- oxidative properties as compared to pure polymers for use in air and space craft; however, there has often been difficulty completely dispersing the clay within the matrices of the polymer. In order to improve this process, the cation exchange capacity of lithium clay is first lowered using twenty-four hour heat treatments of no heat, 130 C, 150 C, or 170 C to fixate the lithium ions within the clay layers so that they are unexchangeable. Generally, higher temperatures have generated lower cation exchange capacities. An ion exchange involving dodecylamine, octadecylamine, or dimethyl benzidine (DMBZ) is then employed to actually expand the clay galleries. X-ray diffraction and transmission electron microscopy can be used to determine whether the clay has been successfully exfoliated. Finally, resins of DMBZ with clay are then pressed into disks for characterization using dynamic mechanical analyzer and oven- aging techniques in order to evaluate their glass transition, modulus strength, and thermal-oxidative stability in comparison to neat DMBZ. In the future, they may also be tested as composites for flexural and laminar shear strength.

  14. Alternative separation of exchange and correlation energies in range-separated density-functional perturbation theory

    OpenAIRE

    Cornaton, Yann; Stoyanova, Alexandrina; Jensen, Hans Jørgen Aa.; Fromager, Emmanuel

    2013-01-01

    An alternative separation of short-range exchange and correlation energies is used in the framework of second-order range-separated density-functional perturbation theory. This alternative separation was initially proposed by Toulouse et al. [Theor. Chem. Acc. 114, 305 (2005)] and relies on a long-range interacting wavefunction instead of the non-interacting Kohn-Sham one. When second-order corrections to the density are neglected, the energy expression reduces to a range-separated double-hyb...

  15. Isotope separation by chemical exchange process: Final technical report

    International Nuclear Information System (INIS)

    The feasibility of a chemical exchange method for the separation of the isotopes of europium was demonstrated in the system EuCl2-EuCl3. The single stage separation factor, α, in this system is 1.001 or 1.0005 per mass unit. This value of α is comparable to the separation factors reported for the U4+ - U6 and U3+ - Y4+ systems. The separation of the ionic species was done by precipitation of the Eu2+ ions or by extraction of the Eu3+ ions with HDEHP. Conceptual schemes were developed for a countercurrent reflux cascades consisting of solvent extraction contractors. A regenerative electrocel, combining simultaneous europium reduction, europium oxidation with energy generation, and europium stripping from the organic phase is described. 32 refs., 22 figs., 6 tabs

  16. Anion-exchange separations of metal ions in thiocyanate media.

    Science.gov (United States)

    Fritz, J S; Kaminski, E E

    1971-05-01

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

  17. PREPARATION OF SA-Fe CATION EXCHANGE MEMBRANE AND IT'S APPLICATION IN ELECTRODIALYSIS FOR TREATING WASTEWATER

    Institute of Scientific and Technical Information of China (English)

    GENG Yamin; CHEN Zhen; ZHENG Xi; HUANG Xuehong; CHEN Riyao

    2006-01-01

    An insoluble SA-Fe membrane was prepared by being linked soluble sodium alginate with FeCl3. SEM was used to observe its surface structure. IR spectrum indicated that Fe3+ was linked with -COOH and -OH in SA membrane. As a cationic exchanging membrane in electrodialysis the membrane was applied in treating inorganic wastewater with high concentration of inorganic ammonia and azote. The results of experiment showed that it was well-selective to ammonia and azote. The percentage of the removal of ammonia and azote in wastewater was up to 80%.

  18. Refolding of Denatured/Reduced Lysozyme Using Weak-Cation Exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    Yan WANG; Bo Lin GONG; Xin Du GENG

    2003-01-01

    Oxidative refolding of the denatured/reduced lysozyme was investigated by using weak-cation exchange chromatography (WCX). The stationary phase of WCX binds to the reduced lysozyme and prevented it from forming intermolecular aggregates. At the same time urea and ammonium sulfate were added to the mobile phase to increase the elution strength for lysozyme. Ammonium sulfate can more stabilize the native protein than a common eluting agent, sodium chloride. Refolding of lysozyme by using this WCX is successfully. It was simply carried out to obtain a completely and correctly refolding of the denatured lysozyme at high concentration of 20.0 mg/mL.

  19. Separation of the isotopes of boron by chemical exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    McCandless, F.P.; Herbst, R.S.

    1995-05-30

    The isotopes of boron, {sup 10}B and {sup 11}B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF{sub 3} and a liquid BF{sub 3} donor molecular addition complex formed between BF{sub 3} gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone. 1 Fig.

  20. Observation of separate cation and anion electrophoretic mobilities in pure ionic liquids

    Science.gov (United States)

    Zhang, Zhiyang; Madsen, Louis A.

    2014-02-01

    Ionic liquids (ILs) continue to show relevance in many fields, from battery electrolytes, to carbon capture, to advanced separations. These highly ion-dense fluids present unique challenges in understanding their electrochemical properties due to deviations in behavior from existing electrolyte theories. Here we present a novel characterization of ILs using electrophoretic NMR (ENMR) to determine separate cation and anion mobilities. This method uses an applied electric field coincident with a pulsed magnetic field gradient to encode the E-field driven flow into NMR signals for cations (1H) and anions (19F). We describe the detailed design of these experiments, including quantitative analysis of artifact mitigation and necessary control experiments. We then explore mobilities and diffusion coefficients for two representative ILs: 1-ethyl-3-methyl imidazolium tetrafluoroborate ([C2mim][BF4]) and 1-ethyl-3-methyl imidazolium trifluoromethanesulfonate ([C2mim][TfO]). We further use the individual ion mobilities to calculate the bulk net conductivity, which closely agrees with bulk conductivity measurements obtained using impedance spectroscopy. These observations represent the first reliable measurements of cation and anion mobilities in pure ILs, with errors of ±7%. We discuss this advanced experimental methodology in detail, as well as implications of these sensitive measurements for understanding conduction mechanisms in ion-dense electrolytes.

  1. Influence of Types and Charges of Exchangeable Cations on Ciprofloxacin Sorption by Montmorillonite

    Institute of Scientific and Technical Information of China (English)

    WU Qingfeng; LI Zhaohui; HONG Hanlie

    2012-01-01

    As one of the most important soil components,montmorillonite plays a vital role in transport and retention of organic pollutants in soils.Ciprofloxacin (CIP),an antibiotic of fluoroquiolones,has been frequently detected in water and soil environments due to its wide use in human and veterinary medicine.In this study,the adsorption of CIP onto different homoionic montmorillonite such as Na-,Ca- and Al-MMT was investigated,and the influence of types and charges of exchangeable cations in the interlayer of montmorillonite on CIP adsorption was evaluated.The results showed that different homoionic montmorillonite exhibited different sorption capacity of CIP.At pH 3,the sorption capacity of CIP decreased in the order Na-MMT > Ca-MMT > Al-MMT,following the lyotropic series.When solution pH increased to 11,the sorption capacity of CIP followed the order Ca-MMT > Al-MMT > Na-MMT.Accompanying CIP adsorption on Ca-MMT,a certain amount of Ca2+ was released into solution.Compared to pH 3,the lower Ca concentration in solution at pH 11 indicated that the adsorption of CIP on Ca-MMT at strong alkaline pH was no longer via cation exchange,and surface complexation or cation bridging might contribute to CIP adsorption.The adsorption of CIP on Na-and Ca-MMT at pH 3 and 11 resulted in the expansion of d-spacing,indicative of intercalation of CIP into the interlayer space of the montmorillonite.However,a decrease of d-spacing was observed when CIP adsorbed on Al-MMT at pH 11,which might be attributed to the dissolution of Al-CIP complex formed between CIP and Al3+ in the interlayer of montmorillonite.The results suggest that the types and charges of exchangeable cations in the interlayer of montmorillonite play an important role in CIP adsorption on montmorillonite.

  2. Hydrogen and water vapor adsorption properties on cation-exchanged mordenite for use to a tritium recovery system

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Yoshinori, E-mail: kawamura.yoshinori@jaea.go.jp [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Edao, Yuki; Iwai, Yasunori; Hayashi, Takumi [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Yamanishi, Toshihiko [Japan Atomic Energy Agency, Rokkasho, Aomori (Japan)

    2014-10-15

    Highlights: • Hydrogen and water vapor adsorption capacity of cation-exchanged mordenite (MOR) with transition metal ion was investigated. • Ag–MOR has indicated considerably large adsorption capacity of hydrogen at 77 K. • Amount of chemisorbed water on MOR is smaller than MS5A or active alumina. • These results contribute to design more effective tritium recovery system. - Abstract: Tritium recovery system using adsorption or catalytic isotope exchange has already been proposed for a solid breeding blanket system of a nuclear fusion reactor. Synthetic zeolite is often used as an adsorbent or a substrate of chemical exchange catalyst. And, it is well known that its property is changed easily by exchanging its cations. Synthetic mordenite is one of zeolites having fairly large silica/alumina ratio. There are many reports about hydrogen adsorption properties of cation-exchanged mordenite so far. And, the present authors also have reported that cation-exchanged mordenite with Ca ion (Ca–MOR) indicated fairly large hydrogen adsorption capacity at 77 K in comparison with Molecular Sieves 5A (MS5A). So, in this work, hydrogen adsorption properties of cation-exchanged mordenite with transition metal ion were investigated mainly. The cation-exchanged mordenite with Ag ion (Ag–MOR) has indicated considerably large hydrogen adsorption capacity in lower pressure range at 77 K in comparison with Ca–MOR. The discussion from the viewpoint of adsorption rate is still remaining, but more compact cryosorption column for tritium recovery system is possible to design if Ag–MOR is adopted.

  3. Preparation and characterization of high capacity, strong cation-exchange fiber based adsorbents.

    Science.gov (United States)

    Schwellenbach, Jan; Taft, Florian; Villain, Louis; Strube, Jochen

    2016-05-20

    Motivated by the demand for more economical capture and polishing steps in downstream processing of protein therapeutics, a novel strong cation-exchange chromatography stationary phase based on polyethylene terephthalate (PET) high surface area short-cut fibers is presented. The fiber surface is modified by grafting glycidyl methacrylate (GMA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and a subsequent derivatization leading to sulfonic acid groups. The obtained cation-exchange fibers have been characterized and compared to commercially available resin and membrane based adsorbers. High volumetric static binding capacities for lysozyme (90mg/mL) and polyclonal human IgG (hIgG, 92mg/mL) were found, suggesting an efficient multi-layer binding within the grafted hydrogel layer. A packed bed of randomly orientated fibers has been tested for packing efficiency, permeability and chromatographic performance. High dynamic binding capacities for lysozyme (50mg/mL) and hIgG (54mg/mL) were found nearly independent of the bed-residence time, revealing a fast mass-transport mechanism. Height equivalent to a theoretical plate (HETP) values in the order of 0.1 cm and a peak asymmetry factor (AF) of 1.8 have been determined by tracer experiments. Additionally inverse size-exclusion chromatography (iSEC) revealed a bimodal structure within the fiber bed, consisting of larger transport channels, formed by the voidage between the fibers, and a hydrogel layer with porous properties. PMID:27106396

  4. Purification of urokinase by combined cation exchanger and affinity chromatographic cartridges.

    Science.gov (United States)

    Hou, K C; Zaniewski, R

    1990-02-23

    Crude urokinase from human urine processed through foam flotation and ammonium sulfate precipitation containing 720 National Health Institute Committee on Thrombolytic Agents U/mg activity was purified by an SP cation exchanger followed by a zinc-chelated affinity chromatographic cartridge. The cartridges were of a radial-flow type formed by using acrylic and cellulose composite matrices. The high rigidity of the matrix structure permits fast flow of protein solutions (liters per minute) and thus allows processing of a large volume of crude urokinase under low operating pressures. A greater than six-fold increase in specific enzyme activity of urokinase was achieved by adsorbing and eluting 1 l of a 3 mg/ml crude urokinase solution on an SP cartridge. The eluent was further purified by passing through a zinc-chelated affinity cartridge to achieve greater than a eighteen-fold increase in urokinase specific activity. This report demonstrates the combined use of a cation exchanger with zinc-chelated chromatographic cartridges in purifying urokinase on a relatively large scale. The relationship between the amount of zinc chelated in the matrix to its effect on urokinase purification is also discussed. PMID:2329161

  5. Effect of ionophores on the rate of intramolecular cation exchange in durosemiquinone ion pairs

    Science.gov (United States)

    Eastman, M. P.; Bruno, G. V.; Mcguyer, C. A.; Gutierrez, A. R.; Shannon, J. M.

    1979-01-01

    The effects of the ionophores 15-crown-5 (15C5), 18-crown-6 (18C6), dibenzo-18-crown-6 (DBC) and cryptand 222 (C222) on intramolecular cation exchange in ion pairs of the sodium salt of the durosemiquinone anion in benzene solution are investigated. Electron paramagnetic resonance spectra of the 18C6 and 15C5 complexes with durosemiquinone reduced by contact with a sodium mirror show an alternating line width which indicates that the sodium ion is being exchanged between equivalent sites near the oxygens of the semiquinone with activation energies of 8.7 and 6.0 kcal/mole and Arrhenius preexponential factors of 9 x 10 to the 12th/sec and 10 to the 12th/sec, respectively. Spectra obtained for the DBC complexes show no evidence of exchange, while those of C222 indicate rapid exchange. It is also noted that the hyperfine splitting constants measured do not change over the 50-K temperature interval studied.

  6. Morphologically Aligned Cation-Exchange Membranes by a Pulsed Electric Field for Reverse Electrodialysis.

    Science.gov (United States)

    Lee, Ju-Young; Kim, Jae-Hun; Lee, Ju-Hyuk; Kim, Seok; Moon, Seung-Hyeon

    2015-07-21

    A low-resistance ion-exchange membrane is essential to achieve the high-performance energy conversion or storage systems. The formation methods for low-resistance membranes are various; one of the methods is the ion channel alignment of an ion-exchange membrane under a direct current (DC) electric field. In this study, we suggest a more effective alignment method than the process with the DC electric field. First, an ion-exchange membrane was prepared under a pulsed electric field [alternating current (AC) mode] to enhance the effectiveness of the alignment. The membrane properties and the performance in reverse electrodialysis (RED) were then examined to assess the membrane resistance and ion selectivity. The results show that the membrane electrical resistance (MER) had a lower value of 0.86 Ω cm(2) for the AC membrane than 2.13 Ω cm(2) observed for the DC membrane and 4.30 Ω cm(2) observed for the pristine membrane. Furthermore, RED achieved 1.34 W/m(2) of maximum power density for the AC membrane, whereas that for the DC membrane was found to be 1.14 W/m(2) [a RED stack assembled with CMX, used as a commercial cation-exchange membrane (CEM), showed 1.07 W/m(2)]. Thereby, the novel preparation process for a remarkable low-resistance membrane with high ion selectivity was demonstrated.

  7. Alternative separation of exchange and correlation energies in range-separated density-functional perturbation theory

    DEFF Research Database (Denmark)

    Cornaton, Y.; Stoyanova, A.; Jensen, Hans Jørgen Aagaard;

    2013-01-01

    An alternative separation of short-range exchange and correlation energies is used in the framework of second-order range-separated density-functional perturbation theory. This alternative separation was initially proposed by Toulouse and relies on a long-range-interacting wave function instead...... expression when expanded in perturbation theory. In contrast to the usual RSDH functionals, RSDHf describes the coupling between long- and short-range correlations as an orbital-dependent contribution. Calculations on the first four noble-gas dimers show that this coupling has a significant effect...

  8. The rapid identification of elution conditions for therapeutic antibodies from cation-exchange chromatography resins using high-throughput screening.

    Science.gov (United States)

    McDonald, Paul; Tran, Benjamin; Williams, Christopher R; Wong, Marc; Zhao, Ti; Kelley, Brian D; Lester, Philip

    2016-02-12

    Cation-exchange chromatography is widely used in the purification of therapeutic antibodies, wherein parameters such as elution pH and counterion concentration require optimization for individual antibodies across different chromatography resins. With a growing number of antibodies in clinical trials and the pressure to expedite process development, we developed and automated a high-throughput batch-binding screen to more efficiently optimize elution conditions for cation-exchange chromatography resins. The screen maps the binding behavior of antibodies and impurities as a function of pH and counterion concentration in terms of a partition coefficient (Kp). Using this approach, the binding behavior of a library of antibodies was assessed on Poros 50HS and SP Sepharose Fast Flow resins. The diversity in binding behavior between antibodies and across resins translated to the requirement of a variable counterion concentration to elute each antibody. This requirement can be met through the use of a gradient elution. However, a gradient of increasing counterion concentration spans the transition from binding to non-binding for impurities as well as the antibody, resulting in the elution of impurities within the antibody elution peak. Step elution conditions that selectively elute the antibody while retaining impurities on the resin can now be rapidly identified using our high-throughput approach. We demonstrate that by correlating antibody Kp to elution pool volume and yield on packed-bed columns and through the calculation of a separation factor, we can efficiently optimize step elution conditions that maximize impurity clearance and yield for each antibody. PMID:26803905

  9. Quantification of melamine in human urine using cation-exchange based high performance liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Panuwet, Parinya; Nguyen, Johnny V; Wade, Erin L; D'Souza, Priya E; Ryan, P Barry; Barr, Dana Boyd

    2012-03-01

    Melamine and cyanuric acid have been implicated as adulterants in baby formula in China and pet foods in North America. In China, the effect of melamine or melamine-cyanuric acid adulteration lead to kidney stone development and acute renal failure in thousands of Chinese infants. A selective and sensitive analytical method was developed to measure melamine in human urine in order to evaluate the extent of potential health implications resulting from the consumption of these types of adulterated products in the general US population. This method involves extracting melamine from human urine using cation-exchange solid-phase extraction, chromatographically separating it from its urinary matrix co-extractants on a silica-based, strong-cation exchange analytical column using high performance liquid chromatography, and analysis using positive mode electrospray ionization tandem mass spectrometry. Quantification was performed using modified, matrix-based isotope dilution calibration covering the concentration range of 0.50-100 ng/mL. The limit of detection, calculated using replicates of blank and low level spiked samples, was 0.66 ng/mL and the relative standard deviations were between 6.89 and 14.9%. The relative recovery of melamine was 101-106%. This method was tested for viability by analyzing samples collected from the general US population. Melamine was detected in 76% of the samples tested, with a geometric mean of 2.37 ng/mL, indicating that this method is suitable for reliably detecting background exposures to melamine or other chemicals from which it can be derived. PMID:22309774

  10. Gradient Elution Method for Successive Separation of Common Cations and Hydrophobic Amines using Suppressed Ion Chromatography

    International Nuclear Information System (INIS)

    In mixed waste the separation and sequential determination of alkali, alkaline earth metals mixed with hydrophobic amines represent a challenge analytical problem. The effect of a new mobile phase (amido-sulfonic acid, ASA) on the suppressed ion chromatographic separation of alkali, alkaline earth metals and hydrophobic amines on Dionex Ion Pac CS12A analytical column was investigated. The addition of surface modifier to the eluent appears to provide better interfacial compatibility between the mobile and stationary phase and facilitates the rapid equilibration of analytes. Incorporation of a very low concentration of the additive may also alters the stationary phase surface by creating a fine-tuning and improves the partition characteristics of the analytes. A dramatic and sufficient elution capability of ASA for sequential separation of the analytes was found and rational mechanisms for the separated analytes are proposed. ASA can act as ion-pairing agent resulting in the separation of a wide variety of amines. The new mobile phase (ASA) is proved to have more successful separation over methanesulfonic acid (MSA) even with eluent free solvent. The proposed method shows that a profound particular effect on the separation of aliphatic diamine (ethylenediamine) and organic amine (cyclohexylamine) was achieved in addition to all common cations and amines using isocratic elution of 18 mM of ASA without organic eluent modifier

  11. Cu2Se and Cu Nanocrystals as Local Sources of Copper in Thermally Activated In Situ Cation Exchange

    KAUST Repository

    Casu, Alberto

    2016-01-27

    Among the different synthesis approaches to colloidal nanocrystals a recently developed toolkit is represented by cation exchange reactions, where the use of template nanocrystals gives access to materials that would be hardly attainable via direct synthesis. Besides, post-synthetic treatments, such as thermally activated solid state reactions, represent a further flourishing route to promote finely controlled cation exchange. Here, we report that, upon in situ heating in a transmission electron microscope, Cu2Se nanocrystals deposited on an amorphous solid substrate undergo partial loss of Cu atoms, which are then engaged in local cation exchange reactions with Cu “acceptors” phases represented by rod- and wire- shaped CdSe nanocrystals. This thermal treatment slowly transforms the initial CdSe nanocrystals into Cu2-xSe nanocrystals, through the complete sublimation of Cd and the partial sublimation of Se atoms. Both Cu “donor” and “acceptor” particles were not always in direct contact with each other, hence the gradual transfer of Cu species from Cu2Se or metallic Cu to CdSe nanocrystals was mediated by the substrate and depended on the distance between the donor and acceptor nanostructures. Differently from what happens in the comparably faster cation exchange reactions performed in liquid solution, this study shows that slow cation exchange reactions can be performed at the solid state, and helps to shed light on the intermediate steps involved in such reactions.

  12. The treatment of liquid radioactive waste containing Americium by using a cation exchange method

    International Nuclear Information System (INIS)

    A research in the treatment of a liquid radioactive waste containing americium has been done. The liquid radioactive waste used in this research was standard solution of U dan Ce with the initial activity of 100 ppm. The experimental investigation is aimed at a study of the effects of the waste pH, the column dimension of IR-120 cation exchanger which is expressed as L/D, the flow rate of a liquid waste and the influence of thiocyanate as a complex agent against the efficiency of a decontamination for uranium and cerium element. The experiment was done by passing downward the feed of uranium and cerium solution into an IR-120 type of cation exchanger with the L/D of 11.37. From the experimental parameters done in this research where the influence of waste pH was varied from 3 - 8, the geometric column (L/D) 11.37, the liquid flow rate was from 2.5 - 10 ml/m and the thiocyanate concentration was between 100 ppm-500 ppm can be concluded that the optimum operational condition for the ion exchange achieved were the waste pH for uranium = 4 and the waste pH for cerium = 6, the flow rate = 2.5 ml/men. From the given maximum value of DF for uranium = 24 (DE = 95.83%) and of DF for cerium = 40 (DE = 97.5%), it can also be concluded that this investigation is to be continued in order that the greater value of DF/DE can be achieved

  13. MINOR ACTINIDE SEPARATIONS USING ION EXCHANGERS OR IONIC LIQUIDS

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-20

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

  14. Independent control of the shape and composition of ionic nanocrystals through sequential cation exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    Luther, Joseph Matthew; Zheng, Haimei; Sadtler, Bryce; Alivisatos, A. Paul

    2009-07-06

    Size- and shape-controlled nanocrystal growth is intensely researched for applications including electro-optic, catalytic, and medical devices. Chemical transformations such as cation exchange overcome the limitation of traditional colloidal synthesis, where the nanocrystal shape often reflects the inherent symmetry of the underlying lattice. Here we show that nanocrystals, with established synthetic protocols for high monodispersity, can be templates for independent composition control. Specifically, controlled interconversion between wurtzite CdS, chalcocite Cu2S, and rock salt PbS occurs while preserving the anisotropic dimensions unique to the as-synthesized materials. Sequential exchange reactions between the three sulfide compositions are driven by the disparate solubilites of the metal ion exchange pair in specific coordinating molecules. Starting with CdS, highly anisotropic PbS nanorods are created, which serve as an important material for studying strong 2-dimensional quantum confinement, as well as for optoelectronic applications. Furthermore, interesting nanoheterostructures of CdS|PbS are obtained by precise control over ion insertion and removal.

  15. Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation

    Directory of Open Access Journals (Sweden)

    Stefan L.

    2013-07-01

    Full Text Available In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na+ instead of Ca2+, Na+ instead of K+. Then, the chemical evolution of cationic resins initially in the Na+ form is characterized in CEM I (Portland cement and CEM III (Portland cement + blastfurnace slag cements at early age and an explanation is proposed for the better stability of CEM III material.

  16. Electrophysical methods of separation of metal cations in the moving salts solution

    Science.gov (United States)

    Gofman, V. N.; Tuksov, I. V.; Timchenko, S. N.; Shamanin, I. V.; Poberezhnikov, A. D.; Kazaryan, M. A.

    2016-07-01

    The results of experiments on the excitation of the phenomenon of selective drift of solvated ions under the influence of an external "asymmetric" electric field to the circulating solution of calcium chloride and magnesium salts in a polar liquid dielectric - water are shown. The purpose of the experiments was to determine the influence of the field frequency and amplitude of the field strength on the excitation phenomenon, and the study of the operating characteristics of the testing apparatus - a dividing cell. The dependences of the separation efficiency of solvated cations from the frequency of the external field and the excitation threshold of the phenomenon from the field strength in the separation cell are defined.

  17. Design of Uranium Isotope Separation Plant by Chemical Exchange

    International Nuclear Information System (INIS)

    The methodology to design a solvent extraction plant for uranium isotope separation by chemical exchange is outlined. This process involves the calculator of the number of stages,the capacity of the plant,the flow rates,and reflux ration in banks of mixer settlers or pulse column used in such a plant. The feed is introduced at the middle of the plant,and the product is withdrawn at one end and the tailings at another. The redox reaction system selected is U(IV)-U(VI) and the equilibrium data of the 40% tri-n-octylamine (TOA) in benzene as the organic phase and 4 M HCI as the aqueous phase are used for the design of the real plant. The resulting analysis for the uranium isotope separation shows that more than 4000 number of stages are required and the reflux ratio is around 700 to produce only 1m3 of product containing 3% of U235 and 0,3% of U235 in the tailings. It is also known that the larger the isotope separation constant the smaller the number of stages needed. The method of design can be used for other systems where the isotope separation constants are more favorable

  18. The Cation Exchange Capacity of Fibrous Feedstuff and Its Nutritive Characteristics

    Institute of Scientific and Technical Information of China (English)

    XING Ting-xian

    2003-01-01

    Current researches on the nutritive characteristics of fibrous feedstuff through determining thefeedstuff cation exchange capacity (CEC) to evaluate its nutritive value at home and abroad were comprehen-sively discribed, and the methods of determining CEC value and the correlation between CEC value and chemi-cal compositions, pH value, and the effect of CEC value on the digestion kinetics in ruminants were also em-phatically introduced. The results of research showed that the CEC values of different feedstuff are different,closely correlated with nitrogen and acid detergent fibre (ADF) and lignin (LIG) content of the feedstuff. Atthe same time, there are markedly effect of CEC value in diet on the nutrients flow of digesta in the digestivetract of ruminants, the degradation rate and digestibility of nutrients in the rumen.

  19. Effect of cation exchange on the subsequent reactivity of lignite chars to steam. [108 references

    Energy Technology Data Exchange (ETDEWEB)

    Hippo, E. J.; Walker, Jr., P. L.

    1977-03-01

    The purpose of this investigation is to determine the role which cations in coal play in the subsequent reactivity of chars. It is hoped that this investigation will aid in an understanding of the catalytic nature of inorganic constituents in coal during its gasification. It was found that increased heat treatment temperature decreased reactivity. The decrease in reactivity was shown to be due, at least in part, to the changes in the nature of the cation with increased heat treatment temperature. Reactivity was found to be a linear function of the amount of Ca(++) exchange on the demineralized coal. The constant utilization factor over the wide range of loadings employed indicated that below 800/sup 0/C the calcium did not markedly sinter. Potassium, sodium, and calcium-containing chars were found to be much more reactive than the iron and magnesium-containing chars. However, the iron and magnesium containing chars were more reactive than chars produced from the demineralized coal. The iron char was highly active at first but the iron phase was quickly oxidized to a comparatively unreactive ..gamma..Fe/sub 2/O/sub 3/-Fe/sub 3/O/sub 4/ phase. The state of magnesium was found to be MgO. Sodium and calcium were equally active as catalysts but not as active as potassium.

  20. Synthesis of high capacity cation exchangers from a low-grade Chinese natural zeolite

    International Nuclear Information System (INIS)

    The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100 g respectively, which are greatly higher than that of the natural zeolite (97 meq/100 g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca2+ > K+ > Mg2+.

  1. Adsorption of arsenate and arsenite from aqueous solutions by cerium-loaded cation exchange resin

    Institute of Scientific and Technical Information of China (English)

    HE Zongliang; TIAN Senlin; NING Ping

    2012-01-01

    The removal of arsenic from water and wastewater is obligatory.Resin is one of the most effective adsorbents for the removal of arsenic.In order to improve the adsorption capacity of resin,a new cerium-loaded cation exchange resin arsenic adsorbent was prepared by impregnating cerium into the cation exchange resin.Batch adsorption experiments under various conditions,such as time,temperature,pH and with coexisting ions were carried out to evaluate the adsorption characteristics of cerium-loaded resin in the removal of As(Ⅴ) and As(Ⅲ) from aqueous solutions.The results showed that the adsorption kinetics of As(Ⅴ) and As(Ⅲ) obeyed a pseudo second-order kinetic model and the adsorption rate constants were 0.3159 and 0.5215 g·mg-1·min-1,respectively.The adsorption of As(Ⅴ) followed the Freundlich adsorption isotherm model and the adsorption isotherm data for As(Ⅲ) fitted well to the Langmuir equation model.The adsorption capacities were 1.0278 mg/g for As(Ⅴ) and 2.5297 mg/g for As(Ⅲ).Both the adsorption of As(Ⅴ) and As(Ⅲ) were found to be pH sensitive and the optimum pH was found to be 5-6.Except for the phosphate ion,the coexisting anionics,such as nitrate,chlorate,sulphate and carbonate,showed no remarkable effect on AS(Ⅴ) and As(Ⅲ) adsorption.The desorption and regeneration study showed that the adsorption capacity of Ce-loaded resin for As(Ⅴ) and As(Ⅲ) could be restored to 97.80% and 69.61%,respectively,using 0.5 mol/L sodium hydroxide solution.

  2. Studies on rapid ion-exchange separation of the transplutonium elements with mineral acid-methanol mixed media

    International Nuclear Information System (INIS)

    In order to study properties of short-lived transplutonium nuclides synthesized by heavy-ion bombardment, three methods for rapid separation of tri-valent transplutonium elements by ion-exchange chromatography with mineral acid-methanol mixed media at elevated temperature were investigated. The first separation method was anion-exchange chromatography with nitric acid-methanol mixed media. The second method was anion-exchange choromatography with dilute hydrochloric acid-methanol mixed media. The third method was improved cation-exchange chromatography with single-column operation using the mixed media of hydrochloric acid and methanol. The separation methods developed were found applicable to studies on synthesis of the trans-plutonium nuclides, 250Fm (T1/2:30 min), 244,245,246Cf (T1/2:20 min, 46 min and 35.7 h, respectively) from the 16O + 238U and12C + 242Pu reactions, and on the decay property of 245Cf. Attempts to search for new actinide nuclides, such as 240U and neutron deficient nuclides of Am, Cm and Bk, were made by a quick purification. The separation system was also applied to the rapid and effective separation of Nd, Am and Cm from spent nuclear fuel samples, for burn-up determination. (J.P.N.) 242 refs

  3. Quantification of unsaturated-zone alteration and cation exchange in zeolitized tuffs at Yucca Mountain, Nevada, USA

    Science.gov (United States)

    Vaniman, David T.; Chipera, Steve J.; Bish, David L.; Carey, J. William; Levy, Schön S.

    2001-10-01

    Zeolitized horizons in the unsaturated zone (UZ) at Yucca Mountain, Nevada, USA, are an important component in concepts for a high-level nuclear waste repository at this site. The use of combined quantitative X-ray diffraction and geochemical analysis allows measurement of the chemical changes that accompanied open-system zeolitization at Yucca Mountain. This approach also provides measures of the extent of chemical migration that has occurred in these horizons as a result of subsequent cation exchange. Mass-balance analysis of zeolitized horizons with extensive cation exchange (drill hole UZ-16) and with only minimal cation exchange (drill hole SD-9) shows that Al is essentially immobile. Although zeolitization occurred in an open system, the mass transfer of constituents other than water is relatively small in initial zeolitization, in contrast to the larger scales of cation exchange that can occur after zeolites have formed. Cation exchange in the clinoptilolite ± mordenite zeolitized horizons is seen in downward-diminishing concentration gradients of Ca, Mg, and Sr exchanged for Na and (to lesser extent) K. Comparison with data from drill hole SD-7, which has multiple zeolitized horizons above the water table, shows that the upper horizons accumulate Ca, Mg, and Sr to such an extent that transport of these elements to the deepest UZ zeolitized horizon can be blocked. Quantitative analysis of zeolite formation yields insight into processes that are implied from laboratory studies and modeling efforts but are otherwise unverified at the site. Such analysis also yields information not provided by or contradicted by some models of flow and transport. The results include the following: (1) evidence of effective downward flow through zeolitic horizons despite the low permeability of these horizons, (2) evidence that alkaline-earth elements accumulated by zeolites are mostly derived from eolian materials in surface soils, (3) validation of the very effective

  4. Chemically modified polymeric resins for separation of cations, organic acids, and small polar moleculea by high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.B.

    1993-07-01

    This thesis is divided into 4 parts: a review, ion chromatography of metal cations on carboxylic resins, separation of hydrophilic organic acids and small polar compounds on macroporous resin columns, and use of eluent modifiers for liquid chromatographic separation of carboxylic acids using conductivity detection.

  5. Ultrathin Sicopion Composite Cation-Exchange Membranes: Characteristics and Electrodialytic Performance following a Conditioning Procedure

    Directory of Open Access Journals (Sweden)

    Erik Ayala-Bribiesca

    2012-01-01

    Full Text Available The aim of this work was to investigate the properties of Sicopion membranes: an ultrathin (≈20 μm composite cation-exchange membrane (CEM made from sulphonated poly(ether-ether-ketone (SPEEK containing different levels of sulphonic-functionalized silica particles (SFSPs. Sicopion membranes were conditioned according to the French Normalization Association procedure, consisting in a series of acid and alkaline washes, and their electrodialytic characteristics were compared to an existent commercial food-grade membrane (CMX-SB. Electrical conductivity of Sicopion membranes was higher than that of CMX-SB membranes (9.92 versus 6.98 mS/cm, as well as their water content (34.0 versus 27.6%. As the SFSP level was reduced, the ion-exchange capacity (IEC of Sicopion membranes increased. Concerning their electrodialytic performances, Sicopion membranes presented a lower demineralization rate than CMX-SB membranes (35.9 versus 45.5%, due to an OH− leakage through the pores created by dislodging the SFSP particles during the conditioning procedure.

  6. Simultaneous Isolation of Lactoferrin and Lactoperoxidase from Bovine Colostrum by SPEC 70 SLS Cation Exchange Resin

    Science.gov (United States)

    Liang, Yafei; Wang, Xuewan; Wu, Mianbin; Zhu, Wanping

    2011-01-01

    In this work, simultaneous isolation of lactoferrin (Lf) and lactoperoxidase (Lp) from defatted bovine colostrum by one-step cation exchange chromatography with SPEC 70 SLS ion-exchange resin was investigated. A RP-HPLC method for Lf and Lp determination was developed and optimized as the following conditions: detection wavelength of 220 nm, flow rate of 1 mL/min and acetonitrile concentration from 25% to 75% within 20 min. The adsorption process of Lf on SPEC 70 SLS resin was optimized using Lf standard as substrate. The maximum static binding capacity of SPEC 70 SLS resin was of 22.0 mg/g resin at 15 °C, pH 7.0 and adsorption time 3 h. The Lf adsorption process could be well described by the Langmuir adsorption isotherm model, with a maximum adsorption capacity of 21.73 mg/g resin at 15 °C. In batch fractionation of defatted colostrum, the binding capacities of SPEC 70 SLS resin for adsorbing Lf and Lp simultaneously under the abovementioned conditions were 7.60 and 6.89 mg/g resin, respectively, both of which were superior to those of CM Sepharose F.F. or SP Sepharose F.F. resins under the same conditions. As a result, SPEC 70 SLS resin was considered as a successful candidate for direct and economic purification of Lf and Lp from defatted colostrum. PMID:22016715

  7. Surface modification of cation exchange membranes by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nemati, Mahsa; Hosseini, Sayed Mohsen; Bagheripour, Ehsan [Faculty of Engineering, Arak University, Arak (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Faculty of Engineering, Razi University, Kermanshah (Iran, Islamic Republic of)

    2016-03-15

    Surface modification of polyvinylchloride based heterogeneous cation exchange membrane was performed by graft polymerization of PAA and PAA-co-PANI/MWCNTs nanoparticles. The ion exchange membranes were prepared by solution casting technique. Spectra analysis confirmed graft polymerization clearly. SEM images illustrated that graft polymerization covers the membranes by simple gel network entanglement. The membrane water content was decreased by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles on membrane surface. Membrane transport number and selectivity declined initially by PAA graft polymerization and then began to increase by utilizing of composite nanoparticles in modifier solution. The sodium and barium flux was improved sharply by PAA and PAAco- 0.01%wt PANI/MWCNTs graft polymerization on membrane surface and then decreased again by more increase of PANI/MWCNTs nanoparticles content ratio in modifier solution. The electrodialysis experiment results in laboratory scale showed higher dialytic rate in heavy metals removal for grafted-PAA and grafted-PAA-co-PANI/MWCNTs modified membrane compared to pristine one. Membrane areal electrical resistance was also decreased by introducing graft polymerization of PAA and PAA-co-PANI/MWCNTs NPs on membrane surface.

  8. Simultaneous isolation of lactoferrin and lactoperoxidase from bovine colostrum by SPEC 70 SLS cation exchange resin.

    Science.gov (United States)

    Liang, Yafei; Wang, Xuewan; Wu, Mianbin; Zhu, Wanping

    2011-09-01

    In this work, simultaneous isolation of lactoferrin (Lf) and lactoperoxidase (Lp) from defatted bovine colostrum by one-step cation exchange chromatography with SPEC 70 SLS ion-exchange resin was investigated. A RP-HPLC method for Lf and Lp determination was developed and optimized as the following conditions: detection wavelength of 220 nm, flow rate of 1 mL/min and acetonitrile concentration from 25% to 75% within 20 min. The adsorption process of Lf on SPEC 70 SLS resin was optimized using Lf standard as substrate. The maximum static binding capacity of SPEC 70 SLS resin was of 22.0 mg/g resin at 15 °C, pH 7.0 and adsorption time 3 h. The Lf adsorption process could be well described by the Langmuir adsorption isotherm model, with a maximum adsorption capacity of 21.73 mg/g resin at 15 °C. In batch fractionation of defatted colostrum, the binding capacities of SPEC 70 SLS resin for adsorbing Lf and Lp simultaneously under the abovementioned conditions were 7.60 and 6.89 mg/g resin, respectively, both of which were superior to those of CM Sepharose F.F. or SP Sepharose F.F. resins under the same conditions. As a result, SPEC 70 SLS resin was considered as a successful candidate for direct and economic purification of Lf and Lp from defatted colostrum.

  9. Simultaneous Isolation of Lactoferrin and Lactoperoxidase from Bovine Colostrum by SPEC 70 SLS Cation Exchange Resin

    Directory of Open Access Journals (Sweden)

    Mianbin Wu

    2011-09-01

    Full Text Available In this work, simultaneous isolation of lactoferrin (Lf and lactoperoxidase (Lp from defatted bovine colostrum by one-step cation exchange chromatography with SPEC 70 SLS ion-exchange resin was investigated. A RP-HPLC method for Lf and Lp determination was developed and optimized as the following conditions: detection wavelength of 220 nm, flow rate of 1 mL/min and acetonitrile concentration from 25% to 75% within 20 min. The adsorption process of Lf on SPEC 70 SLS resin was optimized using Lf standard as substrate. The maximum static binding capacity of SPEC 70 SLS resin was of 22.0 mg/g resin at 15 °С, pH 7.0 and adsorption time 3 h. The Lf adsorption process could be well described by the Langmuir adsorption isotherm model, with a maximum adsorption capacity of 21.73 mg/g resin at 15 °С. In batch fractionation of defatted colostrum, the binding capacities of SPEC 70 SLS resin for adsorbing Lf and Lp simultaneously under the abovementioned conditions were 7.60 and 6.89 mg/g resin, respectively, both of which were superior to those of CM Sepharose F.F. or SP Sepharose F.F. resins under the same conditions. As a result, SPEC 70 SLS resin was considered as a successful candidate for direct and economic purification of Lf and Lp from defatted colostrum.

  10. Superparamagnetic cation-exchange adsorbents for bioproduct recovery from crude process liquors by high-gradient magnetic fishing

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, S.F.L; Hobley, Timothy John;

    2004-01-01

    Different routes were screened for the preparation of superparamagnetic cation-exchange adsorbents for the capture of proteins using high-gradient magnetic fishing. Starting from a polyglutaraldehyde-coated base particle, the most successful of these involved attachment of sulphite to oligomers...

  11. Effects of Acetate on Cation Exchange Capacity of a Zn-Containing Montmorillonite : Physicochemical Significance and Metal Uptake

    NARCIS (Netherlands)

    Stathi, P.; Papadas, I. T.; Enotiadis, A.; Gengler, R. Y. N.; Gournis, D.; Rudolf, P.; Deligiannakis, Y.

    2009-01-01

    Fundamental properties such as cation exchange capacity (CEC), permanent charge, pH(PZC), and metal uptake of a Zn-containing montmorillonite are modified, in a predictable manner, by a mild chemical treatment using acetate. Acetate treatment allows a controllable increase of the CEC of montmorillon

  12. Identification of a crucial histidine involved in metal transport activity in the Arabidopsis cation/H(+) exchanger CAX1

    Science.gov (United States)

    In plants, yeast and bacteria, cation/H(+) exchangers (CAXs), have been shown to translocate Ca(2+) and other metals. The best characterized of these related transporters is the plant vacuolar-localized CAX1. We used site-directed mutagenesis to assess the impact of altering the seven histidine re...

  13. SYNTHESIS OF 2—HYDROXYETHYL ACRYLATE BY USING STRONG ACIDIC CATION ION EXCHANGE RESIN AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    GAODabin

    1992-01-01

    2-Hydroxyethyl acrylate is synthesized from acrylic acid and ethylene glycol under a simple and mild condition by using strong acidic cation ion exchange resin as a catalyst,which could be recycled as long as 10 times with high activation.

  14. Sorption processes and XRD analysis of a natural zeolite exchanged with Pb2+, Cd2+ and Zn2+ cations

    International Nuclear Information System (INIS)

    In this study the Pb2+, Cd2+ and Zn2+ adsorption capacity of a natural zeolite was evaluated in batch tests at a constant pH of 5.5 by polluting this mineral with solutions containing increasing concentrations of the three cations to obtain adsorption isotherms. In addition X-ray powder diffraction (XRD) was used to investigate the changes of zeolite structure caused by the exchange with cations of different ionic radius. The zeolite adsorption capacity for the three cations was Zn > Pb > Cd. Moreover a sequential extraction procedure [H2O, 0.05 M Ca(NO3)2 and 0.02 M EDTA] was applied to zeolite samples used in the adsorption experiments to determine the chemical form of the cations bound to the sorbent. Using this approach it was shown that low concentrations of Pb2+, Cd2+ and Zn2+ were present as water-soluble and exchangeable fractions (27% of the Me adsorbed). The XRD pattern of zeolite, analysed according to the Rietveld method, showed that the main mineralogical phase involved in the adsorption process was clinoptilolite. Besides structure information showed that the incorporation of Pb2+, Cd2+ and Zn2+, into the zeolite frameworks changed slightly but appreciably the lattice parameters. XRD analysis also showed the occurrence of some isomorphic substitution phenomena where the Al3+ ions of the clinoptilolite framework were replaced by exchanged Pb2+ cations in the course of the ion exchange reaction. This mechanism was instead less evident in the patterns of the samples doped with Cd2+ and Zn2+ cations

  15. Purification of Monoclonal Antibodies Using a Fiber Based Cation-Exchange Stationary Phase: Parameter Determination and Modeling

    Directory of Open Access Journals (Sweden)

    Jan Schwellenbach

    2016-10-01

    Full Text Available Monoclonal antibodies (mAb currently dominate the market for protein therapeutics. Because chromatography unit operations are critical for the purification of therapeutic proteins, the process integration of novel chromatographic stationary phases, driven by the demand for more economic process schemes, is a field of ongoing research. Within this study it was demonstrated that the description and prediction of mAb purification on a novel fiber based cation-exchange stationary phase can be achieved using a physico-chemical model. All relevant mass-transport phenomena during a bind and elute chromatographic cycle, namely convection, axial dispersion, boundary layer mass-transfer, and the salt dependent binding behavior in the fiber bed were described. This work highlights the combination of model adaption, simulation, and experimental parameter determination through separate measurements, correlations, or geometric considerations, independent from the chromatographic cycle. The salt dependent binding behavior of a purified mAb was determined by the measurement of adsorption isotherms using batch adsorption experiments. Utilizing a combination of size exclusion and protein A chromatography as analytic techniques, this approach can be extended to a cell culture broth, describing the salt dependent binding behavior of multiple components. Model testing and validation was performed with experimental bind and elute cycles using purified mAb as well as a clarified cell culture broth. A comparison between model calculations and experimental data showed a good agreement. The influence of the model parameters is discussed in detail.

  16. Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation

    Institute of Scientific and Technical Information of China (English)

    Milad Rasouli; Nakisa Yaghobi; Hossein Atashi; Majid Rasouli

    2015-01-01

    The adsorption process was studied for separating para-xylene from xylene mixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO2/Al2O3 was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C8 aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C8 aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylben-zene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

  17. Cation exchange reactions controlling desorption of 90Sr 2+ from coarse-grained contaminated sediments at the Hanford site, Washington

    Science.gov (United States)

    McKinley, J. P.; Zachara, J. M.; Smith, S. C.; Liu, C.

    2007-01-01

    Nuclear waste that bore 90Sr 2+ was accidentally leaked into the vadose zone at the Hanford site, and was immobilized at relatively shallow depths in sediments containing little apparent clay or silt-sized components. Sr 2+, 90Sr 2+, Mg 2+, and Ca 2+ was desorbed and total inorganic carbon concentration was monitored during the equilibration of this sediment with varying concentrations of Na +, Ca 2+. A cation exchange model previously developed for similar sediments was applied to these results as a predictor of final solution compositions. The model included binary exchange reactions for the four operant cations and an equilibrium dissolution/precipitation reaction for calcite. The model successfully predicted the desorption data. The contaminated sediment was also examined using digital autoradiography, a sensitive tool for imaging the distribution of radioactivity. The exchanger phase containing 90Sr was found to consist of smectite formed from weathering of mesostasis glass in basaltic lithic fragments. These clasts are a significant component of Hanford formation sands. The relatively small but significant cation exchange capacity of these sediments was thus a consequence of reaction with physically sequestered clays in sediment that contained essentially no fine-grained material. The nature of this exchange component explained the relatively slow (scale of days) evolution of desorption solutions. The experimental and model results indicated that there is little risk of migration of 90Sr 2+ to the water table.

  18. A study on equilibrium and kinetics of ion exchange of alkaline earth metals using an inorganic cation exchanger - zirconium titanium phosphate

    Indian Academy of Sciences (India)

    Amin Jignasa; Thakkar Rakesh; Chudasama Uma

    2006-03-01

    An advanced inorganic cation exchange material of the class of tetravalent metal acid (TMA) salt, zirconium titanium phosphate (ZTP), has been synthesized by a modified sol-gel technique. ZTP has been characterized by elemental analysis (ICP-AES), thermal analysis (TGA), FTIR and X-ray diffraction studies. The Nernst-Planck equation has been used to study the forward and reverse ion exchange kinetics of Mg (II), Ca (II), Sr (II) and Ba (II) with H (I) at four different temperatures. The mechanism of exchange is particle diffusion, as confirmed by the linear (dimensionless time parameter) vs (time) plots. The exchange process is thus controlled by the diffusion within the exchanger particles for the systems studied herein. Further, various kinetic parameters like self-diffusion coefficient (0), energy of activation () and entropy of activation (*) have been evaluated under conditions favouring a particle diffusion-controlled mechanism.

  19. Alkali recovery using PVA/SiO2 cation exchange membranes with different -COOH contents.

    Science.gov (United States)

    Hao, Jianwen; Gong, Ming; Wu, Yonghui; Wu, Cuiming; Luo, Jingyi; Xu, Tongwen

    2013-01-15

    By changing -COOH content in poly(acrylic acid-co-methacryloxypropyl trimethoxy silane (poly(AA-co-γ-MPS)), a series of PVA/SiO(2) cation exchange membranes are prepared from sol-gel process of poly(AA-co-γ-MPS) in presence of poly(vinyl alcohol) (PVA). The membranes have the initial decomposition temperature (IDT) values of 236-274 °C. The tensile strength (TS) ranges from 17.4 MPa to 44.4 MPa. The dimensional stability in length (DS-length) is in the range of 10%-25%, and the DS-area is in the range of 21%-56% in 65 °C water. The water content (W(R)) ranges from 61.2% to 81.7%, the ion exchange capacity (IEC) ranges from 1.69 mmol/g to 1.90 mmol/g. Effects of -COOH content on diffusion dialysis (DD) performance also are investigated for their potential applications. The membranes are tested for recovering NaOH from the mixture of NaOH/Na(2)WO(4) at 25 - 45 °C. The dialysis coefficients of NaOH (U(OH)) are in the range of 0.006-0.032 m/h, which are higher than those of the previous membranes (U(OH): 0.0015 m/h, at 25 °C). The selectivity (S) can reach up to 36.2. The DD performances have been correlated with the membrane structure, especially the continuous arrangement of -COOH in poly(AA-co-γ-MPS) chain.

  20. Influence of competing inorganic cations on the ion exchange equilibrium of the monovalent organic cation metoprolol on natural sediment.

    Science.gov (United States)

    Niedbala, Anne; Schaffer, Mario; Licha, Tobias; Nödler, Karsten; Börnick, Hilmar; Ruppert, Hans; Worch, Eckhard

    2013-02-01

    The aim of this study was to systematically investigate the influence of the mono- and divalent inorganic ions Na(+) and Ca(2+) on the sorption behavior of the monovalent organic cation metoprolol on a natural sandy sediment at pH=7. Isotherms for the beta-blocker metoprolol were obtained by sediment-water batch tests over a wide concentration range (1-100000 μg L(-1)). Concentrations of the competing inorganic ions were varied within freshwater relevant ranges. Data fitted well with the Freundlich sorption model and resulted in very similar Freundlich exponents (n=0.9), indicating slightly non-linear behavior. Results show that the influence of Ca(2+) compared to Na(+) is more pronounced. A logarithmic correlation between the Freundlich coefficient K(Fr) and the concentration or activity of the competing inorganic ions was found allowing the prediction of metoprolol sorption on the investigated sediment at different electrolyte concentrations. Additionally, the organic carbon of the sediment was completely removed for investigating the influence of organic matter on the sorption of metoprolol. The comparison between the experiments with and without organic carbon removal revealed no significant contribution of the organic carbon fraction (0.1%) to the sorption of metoprolol on the in this study investigated sediment. Results of this study will contribute to the development of predictive models for the transport of organic cations in the subsurface.

  1. Cationic Polymerization of 1,2-Epoxypropane by an Acid Exchanged Montmorillonite Clay in the Presence of Ethylene Glycol

    Directory of Open Access Journals (Sweden)

    Aïcha Hachemaoui

    2003-10-01

    Full Text Available Abstract: The polymerization of propylene oxide (PO catalysed by maghnite-H+ (mag-H+ in the presence of ethylene glycol was investigated. Mag-H+ is a montmorillonite silicate sheet clay was prepared through a straight forward proton exchange process. It was found that the cationic polymerization of PO was initiated by mag-H+ at 20 °C both in bulk and in solution. The effect of the amount of mag-H+ and solvent was studied. These results indicated the cationic nature of the polymerization A possible initiation pathway, via the transfer of protons from mag-H+ to the monomer, is proposed.

  2. 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)

    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)

  3. Strong cation exchange resin for improving physicochemical properties and sustaining release of ranitidine hydrochloride

    Directory of Open Access Journals (Sweden)

    Khan S

    2007-01-01

    Full Text Available In the present study strong cation exchange resin (Amberlite IRP69 was used to improve the physicochemical properties of ranitidine hydrochloride such as taste and bulk properties and to sustain dissolution rate. Drug-resin complexes were prepared using batch method. Drug loading was done under different processing conditions such as temperature, pH, drug-resin ratio, and drug concentration to get the optimum condition for resinate preparation. Resinate prepared under optimized condition was tested for taste, bulk properties and release rate. Degree of bitterness of ranitidine was found to reduce to zero after complexation with resin. Improvement in flow properties was also observed. Angle of repose for resinate was found to be 33.21 o as compared to 42.27 o for ranitidine HCl. Effect of dissolution medium and particle size on in vitro release of drug from resinate was also investigated. Resinate with drug to resin ratio of 2:3 and particle size> 90 µm showed about 90% of drug release within 12 h. The orodispersible tablet formulated from the resinate containing 10% croscarmellose sodium disintegrated within 35 sec in oral cavity and showed similar dissolution profile as the resinate. Tablets were found stable after stability studies with no change in dissolution profile.

  4. Relative activities of siloxane monomers toward the cation exchange resin-catalyst in the equilibration reactions

    Directory of Open Access Journals (Sweden)

    M. N. GOVEDARICA

    2001-07-01

    Full Text Available The relative activities of a number of siloxane monomers, both cyclic and linear, toward the cation exchange resin-equilibration catalyst were determined. The determination was based on the fact that when a particular siloxane compound is added to an arbitrarily chosen equilibrate, it takes part in the equilibration process, provoking certain viscosity changes of the reaction mixture. Taking these viscosity changes as a measure of activities, the following order was obtained: hexamethylcyclotrisiloxane > hexamethyldisiloxane > octamethylcyclotetrasiloxane > one linear all-methyl oligosiloxane of number average molecular weight of approximately 800 > decamethylcyclopentasiloxane. The results obtained by using the described viscosimetrical determination method were controlled by measuring the number average molecular weights of the reaction mixtures at the beginning and at the end of the equilibration process. The deviations of the experimentally measured from the calculated values were less than 20 %, as was found in one equilibration system. In most other systems the deviations were about 10 % which is a very good result which strengthens the validity of the applied determination method.

  5. Use of Cation Exchange Membrane in Soil Potassium Release and Wheat Response to Potassium

    Institute of Scientific and Technical Information of China (English)

    LIGUI-BAO; J.J.SCHOENAU; 等

    1995-01-01

    A pot experiment was conducted in the growth chamber on Saskatchewan soils with different texture to determine the K release status and wheat K demand.The relationship between K uptake and soil available K extracted by cation exchange membrane(CEM-K) and the effcet of K fertilizer on wheat growth and soil available K was also evaluated.Treatments of 0,60 and 120mg K/kg were applied to sandy,low and high K loamy and clay soils,The highest yields were acieved with the application of 120mg K/kg in sandy soil and 60 mg K/kg in other soils.On the whole,the clay soil contributed K more than other soils from slowly available fraction.Regression revealed a linear relationship between the soil available K extracted by NH4OAc(Ka) and CEM-K in suspensions(r=0.93).Results also showed that CEM-K in burial and in suspensions were different not only in the amount but also in correlation with Ka or K uptake.

  6. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    Science.gov (United States)

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  7. Cation- and anion-exchanges induce multiple distinct rearrangements within metallosupramolecular architectures.

    Science.gov (United States)

    Riddell, Imogen A; Ronson, Tanya K; Clegg, Jack K; Wood, Christopher S; Bilbeisi, Rana A; Nitschke, Jonathan R

    2014-07-01

    Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe(II) prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd12L18 prism and the Cd2L3 triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd12L18 structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd10L15 complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd10L15 complex and report solution state data for J-coupling through a CH···F(-) hydrogen bond indicating the strength of these interactions in solution.

  8. Sorption of (226)Ra from oil effluents onto synthetic cation exchangers.

    Science.gov (United States)

    Al Attar, Lina; Safia, Bassam

    2013-07-30

    Increasing environmental awareness is being urged for the safe disposal of (226)Ra-contaminated production water generated in the oil industry. Birnessite, antimony silicate and their cationic derivatives were studied for the take-up of (226)Ra using the batch-type method under experimentally determined parameters, viz. contact time, solution-solid ratio and (226)Ra concentration. Data was expressed in terms of distribution coefficients. Sorption experiments were performed in different concentrations of nitric acid in order to speculate the mechanism of (226)Ra uptake. Variation in the magnitude of sorption efficiency of the materials in the presence of the major components of waste streams, i.e. Na(+), K(+) and Ca(2+), revealed that K(+) was the greatest competitor and Na(+) the least. The application of the materials to sorb (226)Ra from actual oil co-production water samples, collected from Der Ezzor and Al Fourat petroleum companies (DEZPC and AFPC), was interpreted in terms of the exchange properties of the materials and water characterisation. Of the parameters studied, the selectivity of materials was shown to be greatly dependent on the pH of wastewater to be treated. PMID:23623032

  9. A study on Sn4+ cation exchange natural zeolite treated at different temperatures

    International Nuclear Information System (INIS)

    The samples of Sn4+ zeolite are obtained by cation exchange between natural zeolite and SnCl4, and then treated at different temperatures (70 -1000 deg C). By using Moessbauer spectroscopy, X-ray diffraction and infra-red spectroscopy, the change of position of Sn4+ in the zeolite structure with the temperature is studied. The results show that the Sn4+ is situated in the main duct (channel) of the zeolite structure, but with the increase of the temperature the zeolite is dehydrated gradually, then the Sn4+ begins to move from the center of the duct to the walls of the duct, consequently, owing to the increase of the asymmetry of the electric field where the Sn4+ is situated, the quadruple splitting increase with the increase of the temperature. At the same time the SnO2 component increases with the increase of temperature. When heat-treatment temperature reached 1000 deg C the long range order structure of zeolite may be destroyed completely

  10. Adsorption behavior and mechanism of cadmium on strong-acid cation exchange resin

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; WANG Lian-jun; LI Jian-sheng; SUN Xiu-yun; HAN Wei-qing

    2009-01-01

    The adsorption behavior of Cd2+ on 001×7 strong-acid cation exchange resin was studied with the static adsorption method. The adsorption process was analyzed from thermodynamics and kinetics aspects. The influences of experimental parameters such as pH, temperature, initial concentration and adsorption rate were investigated. The experimental results show that in the studied concentration range, 001×7 resin has a good sorption ability for Cd2+, and the equilibrium adsorption data fit to Freundlich isotherms. The adsorption is an exothermic process which runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best adsorption condition is pH 4-5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the desorption efficiency is over 98%. The maximal static saturated adsorption capacity is 355 mg/g (wet resin) at 293 K. The adsorption mechanism of Cd2+ on 001×7 resin was discussed based on IR spectra.

  11. Effects of Experimental Conditions on Extraction Yield of Extracellular Polymeric Substances by Cation Exchange Resin

    Directory of Open Access Journals (Sweden)

    Jinwoo Cho

    2012-01-01

    Full Text Available Effects of experimental conditions on the yield of extracellular polymeric substances (EPSs extraction by cation exchange resin (CER were investigated using activated sludge flocs. The experimental variables included resin dose, extraction time, sample dilution, and storage time. An empirical model was proposed to describe the kinetics of extraction process. The extraction yield increases with the extraction time and CER dose until it reached the maximum amount of EPS extraction. The maximum yield of EPS was affected as well by the sample dilution, exhibiting a decreasing trend with increasing dilution factor. It was also found that the amount of EPS extracted from a raw sample depends on the storage time. Once EPS was extracted from the sample, however, the EPS keeps its original quantity under storage at 4°C. Based on the model, the maximum amount of EPS extraction and yield rate could be estimated for different conditions. Comparing the model parameters allows one to quantitatively compare the extraction efficiencies under various extracting conditions. Based on the results, we recommend the original sample should be diluted with the volume ratio of above 1 : 2 and a raw sample should be treated quickly to prevent the reduction of sample homogeneity and original integrity.

  12. Short communication: Predicting cation exchange capacity from hygroscopic moisture in agricultural soils of Western Europe

    Directory of Open Access Journals (Sweden)

    José Torrent

    2015-12-01

    Full Text Available Soil cation exchange capacity (CEC depends on the extent and negative charge density of surfaces of soil mineral and organic components. Soil water sorption also depends on the extent of such surfaces, giving thus way to significant relationships between CEC and hygroscopic moisture (HM in many soils. In this work, we explored whether CEC could be accurately predicted from HM in agricultural soils of Mediterranean and humid temperate areas in Western Europe. For this purpose, we examined 243 soils across a wide variation range of their intrinsic properties. Soil CEC was determined using 1 M ammonium acetate at pH 7 and HM at an equilibrium air relative humidity (RH of 43% (HM43. Most of the variation of soil CEC was explained by HM43 through a linear function (CEC = 1.4 + 0.78HM43; R2 = 0.962; standard deviation = 2.30 cmolc/kg. Coefficients of the regression equation were similar for subgroups of soils differing in moisture regime, clay mineralogy, carbonate content and organic carbon content. Therefore, soil hygroscopic moisture measurements at a fixed RH level provided a simple, robust, inexpensive method for predicting soil CEC.

  13. Isolation of lactoperoxidase using different cation exchange resins by batch and column procedures.

    Science.gov (United States)

    Fweja, Leonard Wt; Lewis, Michael J; Grandison, Alistair S

    2010-08-01

    Lactoperoxidase (LP) was isolated from whey protein by cation-exchange using Carboxymethyl resin (CM-25C) and Sulphopropyl Toyopearl resin (SP-650C). Both batch and column procedures were employed and the adsorption capacities and extraction efficiencies were compared. The resin bed volume to whey volume ratios were 0.96:1.0 for CM-25C and 0.64:1.0 for SP-650 indicating higher adsorption capacity of SP-650 compared with CM-25C. The effluent LP activity depended on both the enzyme activity in the whey and the amount of whey loaded on the column within the saturation limits of the resin. The percentage recovery was high below the saturation point and fell off rapidly with over-saturation. While effective recovery was achieved with column extraction procedures, the recovery was poor in batch procedures. The whey-resin contact time had little impact on the enzyme adsorption. SDS PAGE and HPLC analyses were also carried out, the purity was examined and the proteins characterised in terms of molecular weights. Reversed phase HPLC provided clear distinction of the LP and lactoferrin (LF) peaks. The enzyme purity was higher in column effluents compared with batch effluents, judged on the basis of the clarity of the gel bands and the resolved peaks in HPLC chromatograms.

  14. Chemical and dimensional evolution of cationic ions exchange resins in cement pastes

    International Nuclear Information System (INIS)

    Ion exchange resins (IERs) are widely used by the nuclear industry to decontaminate radioactive effluents. After use they are usually encapsulated in cementitious materials. However, the solidified waste forms can exhibit a strong expansion, possibly leading to cracking. Its origin is not well understood as well as the conditions when it occurs.In this work, the interactions between cationic resins in the Na+ or Ca2+ form and tricalcium silicate (C3S), Portland cement (CEM I) or Blast furnace slag cement (CEM III/C) are investigated at an early age in order to gain a better understanding of the expansion process.The results show that during the hydration of a paste of C3S or CEM I containing IERs in the Na+ form, the resins exhibit a transient expansion of small magnitude due to the decrease in the osmotic pressure of the interstitial solution. This expansion, which occurs just after cement setting, is sufficient to damage the material which is poorly consolidated for several reasons: small hydration degree, precipitation of less cohesive sodium bearing C-S-H, heterogeneous microstructure with highly porous zones and lastly cleavable crystals of portlandite at the interface between resins and paste. This expansion can be prevented by performing a calcium pretreatment of the resins or by using a CEM III/C cement with a slower rate of hydration than that of Portland cement. (author)

  15. Effect of the Structure of Cations and Anions of Ionic Liquids on Separation of Aromatics from Hydrocarbon Mixtures

    Institute of Scientific and Technical Information of China (English)

    Liu Yansheng; Zhang Zhongxin; Zhang Guofu; Liu Zhichang; Hu Yufeng; Shi Quan; Ji Dejun

    2006-01-01

    The effects of the structure of typical cations and anions of ionic liquids on the separation of benzene and toluene from aromatic/paraffin mixtures were studied. The results showed that the corresponding separation factors were considerably larger than those of the traditional solvents (Benzene+Hexane+sulfolane), and that the ionic liquids could be used as novel solvents for the separation of aromatics from hydrocarbon mixtures. The key parameters governing the ability of ionic liquids for separating aromatics from hydrocarbon sources were investigated. It was found that the effectiveness of the ionic liquids, based on the same anion, changed in the cation order of [BIqu]+< [BPy]+< [BMIM]+. The selectivity of the ionic liquid toward aromatics decreased apparently with the increasing length of the substituted alkyl chain of its cationic head ring. The separation factors, based on the same cation, changed in the anion order of [Tf2N]-<[PF6]-<[BF4]-<[C2H5SO4]-. The solubilities of the aromatics were greater in the ionic liquids based on the former three anions than that in the ionic liquids involving [C2H5SO4]-.

  16. A cation exchange model to describe Cs + sorption at high ionic strength in subsurface sediments at Hanford site, USA

    Science.gov (United States)

    Liu, Chongxuan; Zachara, John M.; Smith, Steve C.

    2004-02-01

    A theoretical and experimental study of cation exchange in high ionic strength electrolytes was performed using pristine subsurface sediments from the U.S. Department of Energy Hanford site. These sediments are representative of the site contaminated sediments impacted by release of high level waste (HLW) solutions containing 137Cs + in NaNO 3 brine. The binary exchange behavior of Cs +-Na +, Cs +-K +, and Na +-K + was measured over a range in electrolyte concentration. Vanselow selectivity coefficients ( Kv) that were calculated from the experimental data using Pitzer model ion activity corrections for aqueous species showed monotonic increases with increasing electrolyte concentrations. The influence of electrolyte concentration was greater on the exchange of Na +-Cs + than K +-Cs +, an observation consistent with the differences in ion hydration energy of the exchanging cations. A previously developed two-site ion exchange model [Geochimica et Cosmochimica Acta 66 (2002) 193] was modified to include solvent (water) activity changes in the exchanger phase through application of the Gibbs-Duhem equation. This water activity-corrected model well described the ionic strength effect on binary Cs + exchange, and was extended to the ternary exchange system of Cs +-Na +-K + on the pristine sediment. The model was also used to predict 137Cs + distribution between sediment and aqueous phase ( Kd) beneath a leaked HLW tank in Hanfordd's S-SX tank using the analytical aqueous data from the field and the binary ion exchange coefficients for the pristine sediment. The Kd predictions closely followed the trend in the field data and were improved by consideration of water activity effects that were considerable in certain regions of the vadose zone plume.

  17. Differential effect of HOE642 on two separate monovalent cation transporters in the human red cell membrane

    DEFF Research Database (Denmark)

    Bernhardt, Ingolf; Weiss, Erwin; Robinson, Hannah C;

    2007-01-01

    Residual K(+) fluxes in red blood cells can be stimulated in conditions of low ionic strength. Previous studies have identified both the non-selective, voltage-dependent cation (NSVDC) channel and the K(+)(Na(+))/H(+) exchanger as candidate pathways mediating this effect, although it is possible...... showed that HOE642 exerted differential effects on the NSVDC channel and the K(+)(Na(+))/H(+) exchanger, confirming that the salt loss observed in low ionic strength solutions represents contributions from at least two independent ion transport pathways. The findings are discussed in the context of red...... blood cell apoptosis (eryptosis) and disease....

  18. Alternative separation of exchange and correlation energies in multi-configuration range-separated density-functional theory

    OpenAIRE

    Stoyanova, Alexandrina; Teale, Andrew M.; Toulouse, Julien; Helgaker, Trygve; Fromager, Emmanuel

    2013-01-01

    International audience The alternative separation of exchange and correlation energies proposed by Toulouse et al. [Theor. Chem. Acc. 114, 305 (2005)] is explored in the context of multi-configuration range-separated density-functional theory. The new decomposition of the short-range exchange-correlation energy relies on the auxiliary long-range interacting wavefunction rather than the Kohn-Sham (KS) determinant. The advantage, relative to the traditional KS decomposition, is that the wave...

  19. Cation Exchange Resins and colonic perforation. What surgeons need to know

    Science.gov (United States)

    Rodríguez-Luna, María Rita; Fernández-Rivera, Enrique; Guarneros-Zárate, Joaquín E.; Tueme-Izaguirre, Jorge; Hernández-Méndez, José Roberto

    2015-01-01

    Introduction Since 1961 the use of Cation Exchange Resins has been the mainstream treatment for chronic hyperkalemia. For the past 25 years different kind of complications derived from its clinical use have been recognized, being the colonic necrosis the most feared and lethal of all. Presentation of case We report a case of a 72-year-old patient with chronic kidney disease, treated with calcium polystyrene sulfonate for hyperkalemia treatment who presented in the emergency department with constipation treated with hypertonic cathartics. With clinical deterioration 48 h later progressed with colonic necrosis requiring urgent laparotomy, sigmoidectomy and open abdomen management with subsequent rectal stump perforation and dead. The histopathology finding: calcium polystyrene sulfonate embedded in the mucosa, consistent with the cause of perforation. Discussion Lillemoe reported the first case series of five uremic patients with colonic perforation associated with the use of SPS in sorbitol in 1987 and in 2009 the FDA removed from the market the SPS containing 70% of sorbitol. The pathophysiologic change of CER goes from mucosal edema, ulcers, pseudomembranes, and the most severe case transmural necrosis. Up to present day, some authors have questioned the use of CER in the setting of lowering serum potassium. Despite its worldwide use in hyperkalemia settings, multiple studies have not demonstrated a significant potassium excretion by CER. Conclusion Despite the low incidence of colonic complication and lethal colonic necrosis associated with the CER clinical use, the general surgeon needs a high index of suspicion when dealing with patients treated with CER and abdominal pain. PMID:26439420

  20. A Sensitivity Analysis of ANN Pedotransfer Functions for spatial modeling of Soil Cation Exchange Capacity

    Directory of Open Access Journals (Sweden)

    A. KESHAVARZI

    2010-12-01

    Full Text Available The development of models simulating soil processes has increased rapidly in recent years. These models havebeen developed to improve the understanding of important soil processes and also to act as tools for evaluatingagricultural and environmental problems. In this research, an artificial neural network (ANN model was developed topredict of soil Cation Exchange Capacity (CEC which was called neural kriging (NK by easily measurablecharacteristics of clay and organic carbon. 134 soil samples were collected from different horizons of 34 soil profileslocated in the Ziaran region, Qazvin province, Iran. The data set was divided into two subsets for calibration (75% andtesting (25% of the model. In order to evaluate the model, root mean square error (RMSE and R2 were used. The valueof RMSE and R2 derived by ANN model were 0.04 and 0.97, respectively. The comparison of RMSE and R2 forvarious ANN models showed that the ANN model with three neurons in hidden layer gives better estimates of soilCEC. Sensitivity analysis was also conducted to investigate the effects of various explanatory parameters on the output.The results indicated that CEC variation was more sensitive to clay content than OC variable. For geostatisticalanalyzing, sampling was done with stratified random method and 34 soil samples from 0 to 15 cm depth were collectedwith auger within 34 locations. For comparing and evaluation of neural kriging and ordinary kriging methods, crossvalidation was used by statistical parameters of RMSE and correlation coefficient (r for test data set. The resultsshowed that neural kriging method has the higher correlation coefficient (0.96 and less RMSE (1.22 than ordinarykriging method in predicting and spatial mapping of soil CEC in unsampled areas.

  1. Spatial Variability of Soil Cation Exchange Capacity in Hilly Tea Plantation Soils Under Different Sampling Scales

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studies on the spatial variability of the soil cation exchange capacity (CEC) were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geostatistics were used to analyze the spatial variability of soil CEC in the tea plantation site on Mengding Mountain in Sichuan Province of China on two sampling scales. It was found that, (1) on the small scale, the soil CEC was intensively spatially correlative, the rate of nugget to sill was 18.84% and the spatially dependent range was 1 818 m, and structural factors were the main factors that affected the spatial variability of the soil CEC; (2) on the microscale, the soil CEC was also consumingly spatially dependent,and the rate of nugget to sill was 16.52%, the spatially dependent range was 311 m, and the main factors affecting the spatial variability were just the same as mentioned earlier. On the small scale, soil CEC had a stronger anisotropic structure on the slope aspect, and a weaker one on the lateral side. According to the ordinary Kriging method, the equivalence of soil CEC distributed along the lateral aspect of the slope from northeast to outhwest, and the soil CEC reduced as the elevation went down. On the microscale, the anisotropic structure was different from that measured on the small scale. It had a stronger anisotropic structure on the aspect that was near the aspect of the slope, and a weaker one near the lateral aspect of the slope. The soil CEC distributed along the lateral aspect of the slope and some distributed in the form of plots.From the top to the bottom of the slope, the soil CEC increased initially, and then reduced, and finally increased.

  2. FACTORS AFFECT THE RELEASE OF PSEUDOEPHDRINE HYDROCHLORIDE FROM THE UNCOATED CATION EXCHANGE RESIN-BASED DRUG DELIVERY SYSTEM IN VITRO

    Institute of Scientific and Technical Information of China (English)

    LI Zhenhua; PI Hongqiong; HE Binglin

    2001-01-01

    In this paper, it was investigated that the effect of parameters such as the ionic strength,pH, counter-ion type of release medium, particle size, and cross linkage of cation exchange resin on the release of model drug pseudoephedrine hydrochloride (PE) from uncoated drug-resin complex.The drug-resin complex was prepared by the reaction of PE with strongly acidic cation exchange resin (001 ×4, 001 ×7, 001 ×14). The result showed that the loading of PE increased with the increase of temperatures. The release of PE from drug-resin complex at 37 ℃ was monitored in vitro.From the experiments, it was found that the release rate of PE depends on the pH, composition of the releasing media, increased at lower pH media or with increase of ionic strength of media. Moreover,the release rate of PE was inversely proportional to the cross-linkage and particle size of the cation exchange resin.

  3. FACTORS AFFECT THE RELEASE OF PSEUDOEPHDRINE HYDROCHLORIDE FROM THE UNCOATED CATION EXCHANGE RESIN—BASED DRUG DELIVERY SYSTEM IN VITRO

    Institute of Scientific and Technical Information of China (English)

    LIZhenhua; PIHongqiong; 等

    2001-01-01

    In this paper,it was investigated that the effect of parameters such as the ionic strength,pH.counter-ion type of release medium,particle size.and cross linkage of cation exchange resin on the release of model drug pseudoephedrine hydrochloride(PE) from uncoated drug-resin complex.The drug-resin complex was pepared by the reaction of PE with strongly acidic cation exchange resin(001×4,001×7,001×14) .The result showed that the loading of PE increased with the increase of temperatures.The release of PE from drug-resin complex at 37℃ was monitored in vitro.From the experiments,it was found that the release rate of PE depends on the pH.comosition of the releasing media,increased at lower pH media or with increase of ionic strength of media.Moreover,the release rate of PE was inversely proportional to the cross-linkage and particle size of the cation exchange resin.

  4. The effect of geometrical presentation of multimodal cation-exchange ligands on selective recognition of hydrophobic regions on protein surfaces.

    Science.gov (United States)

    Woo, James; Parimal, Siddharth; Brown, Matthew R; Heden, Ryan; Cramer, Steven M

    2015-09-18

    The effects of spatial organization of hydrophobic and charged moieties on multimodal (MM) cation-exchange ligands were examined by studying protein retention behavior on two commercial chromatographic media, Capto™ MMC and Nuvia™ cPrime™. Proteins with extended regions of surface-exposed aliphatic residues were found to have enhanced retention on the Capto MMC system as compared to the Nuvia cPrime resin. The results further indicated that while the Nuvia cPrime ligand had a strong preference for interactions with aromatic groups, the Capto MMC ligand appeared to interact with both aliphatic and aromatic clusters on the protein surfaces. These observations were formalized into a new set of protein surface property descriptors, which quantified the local distribution of electrostatic and hydrophobic potentials as well as distinguishing between aromatic and aliphatic properties. Using these descriptors, high-performing quantitative structure-activity relationship (QSAR) models (R(2)>0.88) were generated for both the Capto MMC and Nuvia cPrime datasets at pH 5 and pH 6. Descriptors of electrostatic properties were generally common across the four models; however both Capto MMC models included descriptors that quantified regions of aliphatic-based hydrophobicity in addition to aromatic descriptors. Retention was generally reduced by lowering the ligand densities on both MM resins. Notably, elution order was largely unaffected by the change in surface density, but smaller and more aliphatic proteins tended to be more affected by this drop in ligand density. This suggests that modulating the exposure, shape and density of the hydrophobic moieties in multimodal chromatographic systems can alter the preference for surface exposed aliphatic or aromatic residues, thus providing an additional dimension for modulating the selectivity of MM protein separation systems. PMID:26292626

  5. Separation of chloride and sulfate ions in univalent and divalent cation forms from aqueous streams.

    Science.gov (United States)

    Bader, M S

    2000-04-28

    The precipitation and separation of chloride and sulfate in several cation forms (sodium, potassium, magnesium, calcium, strontium, and barium) from aqueous streams were studied using isopropylamine (IPA) and ethylamine (EA) as precipitation solvents. The precipitation fractions (P) of the tested chloride salts at 5000 and 10,000 ppm by both IPA and EA over the studied range of solvents volume ratio (V(R)) were relatively identical (18-60%) and their small variations were within their experimental uncertainty. The P of combined sulfate at 1000 ppm (56-99.5%) and chloride at 5000 ppm (28-62%) in the form of calcium by IPA over the studied range of V(R) were appreciably higher than the P of sulfate (10-98.5%) from calcium sulfate in the absence of calcium chloride, or the P of chloride (18-58%) from calcium chloride in the absence of calcium sulfate. The P of chloride from oil-field-produced waters at 106,654 ppm (20-88%) by both IPA and EA were higher than the P of chloride from diluted produced water at 20,000 (17-68%) and 10,000 ppm (16-65%) over the studied range of V(R). The small amounts of sulfate present in the produced waters (e.g., 435 ppm) were completely removed at V(R) of 0.1 (the first stage of precipitation). Consistency tests performed on the acquired data indicated a good level of experimental consistency. Two model equations (2-Suffix and 3-Suffix) derived from thermodynamic principles of solid-liquid equilibrium (SLE) criteria were employed to correlate the acquired data. While both equations were adequate for correlating the precipitation data, the 3-Suffix equation was more accurate.

  6. Efficient separations and processing crosscutting program 1996 technical exchange meeting. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    This document contains summaries of technology development presented at the 1996 Efficient Separations and Processing Crosscutting Program Technical Exchange Meeting. This meeting is held annually to promote a free exchange of ideas among technology developers, potential users and other interested parties within the EM community. During this meeting the following many separation processes technologies were discussed such as ion exchange, membrane separation, vacuum distillation, selective sorption, and solvent extraction. Other topics discussed include: waste forms; testing or inorganic sorbents for radionuclide and heavy metal removal; selective crystallization; and electrochemical treatment of liquid wastes. This is the leading abstract, individual papers have been indexed separately for the databases.

  7. Efficient separations and processing crosscutting program 1996 technical exchange meeting. Proceedings

    International Nuclear Information System (INIS)

    This document contains summaries of technology development presented at the 1996 Efficient Separations and Processing Crosscutting Program Technical Exchange Meeting. This meeting is held annually to promote a free exchange of ideas among technology developers, potential users and other interested parties within the EM community. During this meeting the following many separation processes technologies were discussed such as ion exchange, membrane separation, vacuum distillation, selective sorption, and solvent extraction. Other topics discussed include: waste forms; testing or inorganic sorbents for radionuclide and heavy metal removal; selective crystallization; and electrochemical treatment of liquid wastes. This is the leading abstract, individual papers have been indexed separately for the databases

  8. Separation of thorium and uranium in nitric acid solution using silica based anion exchange resin.

    Science.gov (United States)

    Chen, Yanliang; Wei, Yuezhou; He, Linfeng; Tang, Fangdong

    2016-09-30

    To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method.

  9. Effect of efficient microorganisms on cation exchange capacity in acacia seedlings (Acacia melanoxylon) for soil recovery in Mondonedo, Cundinamarca

    International Nuclear Information System (INIS)

    We determined the effect of efficient microorganisms (EM) on the cation exchange capacity for soil recovery in the municipality of Mondonedo, Cundinamarca. A greenhouse unit was installed in order to maintain stable conditions. After harvesting, sifted and homogenization of the soil sample, initial physical and chemical analyses were made. For the experimental units we used Acacia melanoxylon seedlings from Zabrinsky. A completely randomized design was done with eight treatments and three repetitions. For the maintenance and monitoring of the seedlings behaviour, a frequency of irrigation of three times per week was found. The application of the EM was done during three months: in the first month, it was applied four times (once a week); during the second month, it was applied twice (biweekly), and during the third month there was only one application. Additionally, every 15 days morphological analyses were made (number of leaves, branches and stem diameter). In the end, soil samples were taken from each plant pot. In the laboratory we analysed the cation exchange capacity, alkali ion exchange, saturation alkali, relations between elements and plant tissue. These were done using an atomic absorption spectrophotometer. Statistical analyses consisted on multiple comparisons test and variance tests, in order to find whether or not treatments exhibited significant differences. In that way, the best alternative for improving environmental quality of eroded soils as the Zabrinsky desert is the efficient microorganisms in 5% doses in irrigation water. Additionally, the cation exchange capacity must be enhanced using organic fertilizers (compost, mulch and gallinaza) in one pound doses, and chemical fertilizers: electrolytic Mn (0.0002 g), Cu (0.0002 g), Zn (0.0001 g), URFOS 44 (166.66 g) and klip-boro (5 g).

  10. Effect of bore fluid composition on microstructure and performance of a microporous hollow fibre membrane as a cation-exchange substrate.

    Science.gov (United States)

    Lazar, R A; Mandal, I; Slater, N K H

    2015-05-15

    Micro-capillary film (MCF) membranes are effective platforms for bioseparations and viable alternatives to established packed bed and membrane substrates at the analytical and preparative chromatography scales. Single hollow fibre (HF) MCF membranes with varied microstructures were produced in order to evaluate the effect of the bore fluid composition used during hollow fibre extrusion on their structure and performance as cation-exchange adsorbers. Hollow fibres were fabricated from ethylene-vinyl alcohol (EVOH) copolymer through solution extrusion followed by nonsolvent induced phase separation (NIPS) using bore fluids of differing composition (100wt.% N-methyl-2-pyrrolidone (NMP), 100wt.% glycerol, 100wt.% water). All HFs displayed highly microporous and mesoporous microstructures, with distinct regions of pore size membrane performance as a result of inner surface porosity was established with a view to applying this parameter for the optimisation of multi-capillary MCF performance in future studies. PMID:25840664

  11. Investigation of Polyacrylate Anion-Exchangers for Separation of Rare Earth Element Complexes with EDTA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The rare earth complexes with EDTA, Ln(edta), show an unusual sequence of affinity for the anion-exchangers. The sorption and chromatographic separation of Y3+ for Nd3+ complexes with EDTA was studied by using the strongly basic gel and macroporous polyacrylate anion-exchangers, Amberlite IRA 458 and Amberlite 958, and the weakly basic gel polyacrylate anion-exchanger, Amberlite IRA-68. The investigations on sorption and separation of rare earth complexes with EDTA on the polyacrylate anion-exchangers applied mainly in the environment protection so far indicate that they can be applied in anionexchange separation of lanthanide complexes with aminopolycarboxylic acids. It was shown that the weakly basic polyacrylate gel anion-exchanger Amberlite IRA-68 is the most effective in purification of Y3+ from Nd3+ in comparison with the strongly basic anion-exchangers of this type.

  12. Analysis of statistical thermodynamic model for binary protein adsorption equilibria on cation exchange adsorbent

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiaopeng; SU Xueli; SUN Yan

    2007-01-01

    A study of nonlinear competitive adsorption equilibria of proteins is of fundamental importance in understanding the behavior of preparative chromatographic separation.This work describes the nonlinear binary protein adsorption equilibria on ion exchangers by the statistical thermodynamic (ST) model.The single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin(BSA)on SP Sepharose FF were determined by batch adsorption experiments in 0.05 mol/L sodium acetate buffer at three pH values(4.5,5.0 and 5.5)and three NaCl concentrations(0.05,0.10 and 0.15 mol/L)at pH 5.0.The ST model was found to depict the effects of pH and ionic strength on the single-component equilibria well,with model parameters depending on the pH and ionic strength.Moreover,the ST model gave acceptable fitting to the binary adsorption data with the fltted singlecomponent model parameters,leading to the estimation of the binary ST model parameter.The effects of pH and ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories.Results demonstrate the availability of the ST model for describing nonlinear competitive protein adsorption equilibria in the presence of two proteins.

  13. Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

    International Nuclear Information System (INIS)

    This work has been focused on the synthesis and characterization of different blended membranes SPEEK-35PVA (Water), SPEEK-35PVA (DMAc) prepared by casting and nanofiber-reinforced proton exchange membranes Nafion-PVA-15, Nafion-PVA-23 and SPEEK/PVA-PVB. The two first reinforced membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The last composite membrane is considered because the PVA is a hydrophilic polymer which forms homogeneous blends with SPEEK suitable to obtain high proton conductivity, while the hydrophobic PVB can produce blends in a phase separation morphology in which very low water uptake can be found. The synthesized membranes showed an outstanding stability, high proton conductivity, and enhanced mechanical and barrier properties. The membranes were characterized in single chamber microbial fuel cells (SCMFCs) using electrochemically enriched high sodic saline hybrid H-inocula (Geobacter metallireducen, Desulfurivibrio alkaliphilus, and Marinobacter adhaerens) as biocatalyst. The best performance was obtained with Nafion-PVA-15 membrane, which achieved a maximum power density of 1053 mW/m3 at a cell voltage of 340 mV and displayed the lowest total internal resistance (Rint ≈ 522 Ω). This result is in agreement with the low oxygen permeability and the moderate conductivity found in this kind of membranes. These results are encouraging towards obtaining high concentrated sodic saline model wastewater exploiting MFCs

  14. Purification of drinking water from radioactive contamination by final consumers by means of combined cation and anion exchangers

    International Nuclear Information System (INIS)

    It should be tried to develop an apparatus which makes it possible for the final consumer to purify the drinking water himself in the case of a radioactive contamination of the water. After thorough preliminary studies the most suitable kinds of exchange resins and the best arrangement for a combined cation and anion exchange resins and the best arrangement for a combined cation and anion exchange equipment were determined in inactive preliminary tests. Subsequent the useful capacity (NK) and the purifying factor (RF) were determined for the fission products 90Sr, 131I and 137Cs. The results were for 90Sr: NK = 30 1/2 x 0.5 l resin, RF >= 4.102, for 131I: NK = 32 1/2 x 0.5 l resin, RF = 3.7.102 and for 137Cs: NK > 35 1/2 x 0.5 l resin, RF >= 103. With 2 x 1 l resin the concentration of possible fission products in water can be reduced by 2 orders of magnitude ore more. A proposal for the construction of a household decontamination equipment for drinking water is made. The cost of production will be about A.S. 400,-- to 600,--. (author)

  15. Consistent effects of canopy vs. understory nitrogen addition on the soil exchangeable cations and microbial community in two contrasting forests.

    Science.gov (United States)

    Shi, Leilei; Zhang, Hongzhi; Liu, Tao; Zhang, Weixin; Shao, Yuanhu; Ha, Denglong; Li, Yuanqiu; Zhang, Chuangmao; Cai, Xi-An; Rao, Xingquan; Lin, Yongbiao; Zhou, Lixia; Zhao, Ping; Ye, Qing; Zou, Xiaoming; Fu, Shenglei

    2016-05-15

    Anthropogenic N deposition has been well documented to cause substantial impacts on the chemical and biological properties of forest soils. In most studies, however, atmospheric N deposition has been simulated by directly adding N to the forest floor. Such studies thus ignored the potentially significant effect of some key processes occurring in forest canopy (i.e., nitrogen retention) and may therefore have incorrectly assessed the effects of N deposition on soils. Here, we conducted an experiment that included both understory addition of N (UAN) and canopy addition of N (CAN) in two contrasting forests (temperate deciduous forest vs. subtropical evergreen forest). The goal was to determine whether the effects on soil exchangeable cations and microbial biomass differed between CAN and UAN. We found that N addition reduced pH, BS (base saturation) and exchangeable Ca and increased exchangeable Al significantly only at the temperate JGS site, and reduced the biomass of most soil microbial groups only at the subtropical SMT site. Except for soil exchangeable Mn, however, effects on soil chemical properties and soil microbial community did not significantly differ between CAN and UAN. Although biotic and abiotic soil characteristics differ significantly and the responses of both soil exchangeable cations and microbial biomass were different between the two study sites, we found no significant interactive effects between study site and N treatment approach on almost all soil properties involved in this study. In addition, N addition rate (25 vs. 50kgNha(-1)yr(-1)) did not show different effects on soil properties under both N addition approaches. These findings did not support previous prediction which expected that, by bypassing canopy effects (i.e., canopy retention and foliage fertilization), understory addition of N would overestimate the effects of N deposition on forest soil properties, at least for short time scale. PMID:26930308

  16. 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.

  17. 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

  18. The elution of erbium from a cation exchanger bed by means of the N-hydroxyethyl-ethylene-diamine triacetic acid

    International Nuclear Information System (INIS)

    A physicochemical study of the phenomena resulting when erbium is eluted from a cation-exchanger bed at a steady by means of the N-hydroxyethyl-ethylene-diamine-triacetic acid (HEDTA) is made. Two different retaining beds are used, a hydrogen bed, in which no ammonium passes through, and a zinc bed, which leaks ammonium ion. Good agreement between experimental and calculated values by using the equations deduced for the concentrations of the main species has been achieved, with errors around 1-2% in most of the experiments. (Author) 69 refs

  19. Applications of Time-Resolved Synchrotron X-ray Diffraction to Cation Exchange, Crystal Growth and Biomineralization Reactions

    International Nuclear Information System (INIS)

    Advances in the design of environmental reaction cells and in the collection of X-ray diffraction data are transforming our ability to study mineral-fluid interactions. The resulting increase in time resolution now allows for the determination of rate laws for mineral reactions that are coupled to atomic-scale changes in crystal structure. Here we address the extension of time-resolved synchrotron diffraction techniques to four areas of critical importance to the cycling of metals in soils: (1) cation exchange; (2) biomineralization; (3) stable isotope fractionation during redox reactions; and (4) nucleation and growth of nanoscale oxyhydroxides.

  20. Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

    A study of time evolution of the impedance curves measured in the system “IL aqueous solution/Nafion-112 membrane/IL aqueous solution” was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA+ hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

  1. Semilocal exchange hole with an application to range-separation density functional

    CERN Document Server

    Tao, Jianmin; Scuseria, Gustavo E

    2016-01-01

    Exchange-correlation hole is a central concept in density functional theory. It not only provides justification for an exchange-correlation energy functional, but also serves as a local ingredient in nonlocal range-separation density functional. However, due to the nonlocal nature, modelig the conventional exact exchange hole presents a great challenge to density functional theory. In this work, we propose a semilocal exchange hole underlying the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional. The present model is distinct from previous models at small separation between an electron and the hole around the electron. It is also different in the way it interpolates between the rapidly varying iso-orbital density and the slowly varying density, which is determined by the wave vector analysis based on the exactly solvable infinite barrier model for jellium surface. Our numerical tests show that the exchange hole generated from this model mimics the conventional exact exchange hole quite well for atoms....

  2. Uncertainties of Gaseous Oxidized Mercury Measurements Using KCl-Coated Denuders, Cation-Exchange Membranes, and Nylon Membranes: Humidity Influences.

    Science.gov (United States)

    Huang, Jiaoyan; Gustin, Mae Sexauer

    2015-05-19

    Quantifying the concentration of gaseous oxidized mercury (GOM) and identifying the chemical compounds in the atmosphere are important for developing accurate local, regional, and global biogeochemical cycles. The major hypothesis driving this work was that relative humidity affects collection of GOM on KCl-coated denuders and nylon membranes, both currently being applied to measure GOM. Using a laboratory manifold system and ambient air, GOM capture efficiency on 3 different collection surfaces, including KCl-coated denuders, nylon membranes, and cation-exchange membranes, was investigated at relative humidity ranging from 25 to 75%. Recovery of permeated HgBr2 on KCl-coated denuders declined by 4-60% during spikes of relative humidity (25 to 75%). When spikes were turned off GOM recoveries returned to 60 ± 19% of permeated levels. In some cases, KCl-coated denuders were gradually passivated over time after additional humidity was applied. In this study, GOM recovery on nylon membranes decreased with high humidity and ozone concentrations. However, additional humidity enhanced GOM recovery on cation-exchange membranes. In addition, reduction and oxidation of elemental mercury during experiments was observed. The findings in this study can help to explain field observations in previous studies. PMID:25877790

  3. 阳离子交换树脂改性研究进展%Review on the development of cation exchange resin’s modification

    Institute of Scientific and Technical Information of China (English)

    陈桂; 向柏霖; 袁叶; 刘跃进

    2016-01-01

    强酸性阳离子交换树脂含有大量的强酸性基团,具有选择、交换、吸收和催化等功能,但其存在耐高温性能差、酸强度低等问题,故需要对其进行改性。改性的阳离子交换树脂广泛应用于水处理、有机合成、分离处理、环境保护及生物制药等领域。本文简要介绍了近年来强酸性阳离子交换树脂的改性方法,主要包含:金属离子改性(Al3+、Sn4+、Zn2+、Ti4+、Fe3+和 Fe2+、Ce4+和 Ga3+、Ni2+、Zr4+、Pd2+等)、磺化改性、巯基改性、胺化改性及其他类改性等方法;指出了其存在的问题,分析了改性阳离子交换树脂的未来发展方向,开发和研制具有耐高热和化学稳定性的树脂载体材料成为其研究的关键。除此之外,对树脂进行各种改性处理也是改善树脂综合性能、扩大其应用范围的重要方法。%Strong-acidic cation exchange resin contained a large number of strong acid groups,which renders it diversed functions of selection,exchange,absorption and catalysis,etc. But the inherent defects of poor high temperature resistance and low acid strength,make it obliged to be modified. Modified cation exchange resins have been widely used in water treatment,organic synthesis, separation and treatment,environmental protection and biological pharmaceutical,etc. The modification methods of strong-acid cation exchange resin were reviewed,mainly including: metal ion modification(Al3+、Sn4+、Zn2+、Ti4+、Fe3+ and Fe2+、Ce4+ and Ga3+、Ni2+、Zr4+、Pd2+,etc),sulfonation, thiol and amination modification,and other modifications,etc. The prospect of application of modified cation exchange resins was discussed.The key of the research was to prepare the resin support material with high heat resistance and chemical stability. In addition,the modification of resin was also an important method to improve its comprehensive performance and extend its applications.

  4. Heat exchangers with several heat exchanger matrices mounted in a common casing for separately conducted media

    International Nuclear Information System (INIS)

    The heat exchanger is suited for plants with a closed gas cycle such as, e. g., HTR with a helium turbine or drive units for vehicles. It contains heat exchanger matrices running parallel to each other and formed by the folds of a uniformly folded band and by walls covering the saddles of the folds. Two neighbouring matrices each are combined to form a heat exchanger unit and supported between supporting walls. The heat exchanger unit is not firmly connected with these supporting walls and therefore can easily to be inserted or dismounted. For sealing purposes, the fold saddles are contacting the supporting walls because of the high pressure of the meUWIdium, Ior the remaining seals between hp and lp-compartments labyrinth boxes being provided. (UWI)

  5. Electrodialysis-ion exchange for the separation of dissolved salts

    Energy Technology Data Exchange (ETDEWEB)

    Baroch, C.J. [Wastren, Inc., Westminster, CO (United States); Grant, P.J. [Wastren, Inc., Hummelstown, PA (United States)

    1995-10-01

    The Department of Energy generates and stores a significant quantity of low level, high level, and mixed wastes. As some of the DOE facilities are decontaminated and decommissioned, additional and possibly different forms of wastes will be generated. A significant portion of these wastes are aqueous streams containing acids, bases, and salts, or are wet solids containing inorganic salts. Some of these wastes are quite dilute solutions, whereas others contain large quantities of nitrates either in the form of dissolved salts or acids. Many of the wastes are also contaminated with heavy metals, radioactive products, or organics. Some of these wastes are in storage because a satisfactory treatment and disposal processes have not been developed. There is considerable interest in developing processes that remove or destroy the nitrate wastes. Electrodialysis-Ion Exchange (EDIX) is a possible process that should be more cost effective in treating aqueous waste steams. This report describes the EDIX process.

  6. Changes of Soil Water, Organic Matter, and Exchangeable Cations Along a Forest Successional Gradient in Southern China

    Institute of Scientific and Technical Information of China (English)

    YAN Jun-Hua; ZHOU Guo-Yi; ZHANG De-Qiang; CHU Guo-Wei

    2007-01-01

    Information on the distribution patterns of soil water content (SWC), soil organic matter (SOM), and soil exchangeable cations (SEC) is important for managing forest ecosystems in a sustainable manner. This study investigated how SWC, SOM, and SEC were influenced in forests along a successional gradient, including a regional climax (monsoon evergreen broad-leaved forest, or MEBF), a transitional forest (coniferous and broad-leaved mixed forest, or MF), and a pioneer forest (coniferous Masson pine (Pinus massoniana) forest, or MPF) of the Dinghushan Biosphere Reserve in the subtropical region of southern China. SWC, SOM, and SEC excluding Ca2+ were found to increase in the soil during forest succession, being highest in the top soil layer (0 to 15 cm depth) except for Na+. The differences between soil layers were largest in MF. This finding also suggested that the nutrients were enriched in the topsoil when they became increasingly scarce in the soil. There were no significant differences (P = 0.05) among SWC, SOM, and SBC. A linear, positive correlation was found between SWC and SOM. The correlation between SOM and cation exchange capacity (CEC) was statistically significant, which agreed with the theory that the most important factor determining SEC is SOM. The ratio of K+ to Na+ in the topsoil was about a half of that in the plants of each forest. MF had the lowest exchangeable Ca2+ concentration among the three forests and Ca2+:K+ in MPF was two times higher than that in MF. Understanding the changes of SWC, SOM, and CEC during forest succession would be of great help in protecting all three forests in southern China.

  7. Selective cation exchange in the core region of Cu2-xSe/Cu2-xS core/shell nanocrystals.

    Science.gov (United States)

    Miszta, Karol; Gariano, Graziella; Brescia, Rosaria; Marras, Sergio; De Donato, Francesco; Ghosh, Sandeep; De Trizio, Luca; Manna, Liberato

    2015-09-30

    We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), which are known to induce rapid exchange within metal chalcogenide nanocrystals (NCs) at room temperature. At the initial stage of the reaction, the guest ions diffused through the Cu2-xS shell and reached the Cu2-xSe core, replacing first Cu(+) ions within the latter region. These experiments prove that CE in copper chalcogenide NCs is facilitated by the high diffusivity of guest cations in the lattice, such that they can probe the whole host structure and identify the preferred regions where to initiate the exchange. For both guest ions, CE is thermodynamically driven as it aims for the formation of the chalcogen phase characterized by the lower solubility under the specific reaction conditions.

  8. Multi-column step-gradient chromatography system for automated ion exchange separations

    International Nuclear Information System (INIS)

    A multi-column step-gradient chromatography system has been designed to perform automated sequential separations of radionuclides by ion exchange chromatography. The system consists of a digital programmer with automatic stream selection valve, two peristaltic pumps, ten columns, and a fraction collector. The automation allows complicated separations of radionuclides to be made with minimal analyst attention and allows for increased productivity and reduced cost of analyses. Results are reported for test separations on mixtures of radionuclides by the system

  9. Membrane resistance: The effect of salinity gradients over a cation exchange membrane

    NARCIS (Netherlands)

    Galama, A.H.; Vermaas, D.A.; Veerman, J.; Saakes, M.; Rijnaarts, H.; Post, J.W.; Nijmeijer, K.

    2014-01-01

    Ion exchange membranes (IEMs) are used for selective transport of ions between two solutions. These solutions are often different in concentration or composition. The membrane resistance (R-M) is an important parameter affecting power consumption or power production in electrodialytic processes. In

  10. Membrane resistance : The effect of salinity gradients over a cation exchange membrane

    NARCIS (Netherlands)

    Galama, A. H.; Vermaas, D. A.; Veerman, J.; Saakes, M.; Rijnaarts, H. H. M.; Post, J. W.; Nijmeijer, K.

    2014-01-01

    Ion exchange membranes (IEMs) are used for selective transport of ions between two solutions. These solutions are often different in concentration or composition. The membrane resistance (R-M) is an important parameter affecting power consumption or power production in electrodialytic processes. In

  11. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes.

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders.

  12. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes.

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders. PMID:26542108

  13. Alternative separation of exchange and correlation energies in multi-configuration range-separated density-functional theory

    CERN Document Server

    Stoyanova, Alexandrina; Toulouse, Julien; Helgaker, Trygve; Fromager, Emmanuel

    2013-01-01

    The alternative separation of exchange and correlation energies proposed by Toulouse et al. [Theor. Chem. Acc. 114, 305 (2005)] is explored in the context of multi-configuration range-separated density-functional theory. The new decomposition of the short-range exchange-correlation energy relies on the auxiliary long-range interacting wavefunction rather than the Kohn-Sham (KS) determinant. The advantage, relative to the traditional KS decomposition, is that the wavefunction part of the energy is now computed with the regular (fully-interacting) Hamiltonian. One potential drawback is that, because of double counting, the wavefunction used to compute the energy cannot be obtained by minimizing the energy expression with respect to the wavefunction parameters. The problem is overcome by using short-range optimized effective potentials (OEPs). The resulting combination of OEP techniques with wavefunction theory has been investigated in this work, at the Hartree-Fock (HF) and multi-configuration self-consistent-f...

  14. Onset of size independent cationic exchange in nano-sized CoFe2O4 induced by electronic excitation

    International Nuclear Information System (INIS)

    Highlights: • Electronic excitation induced crystalline order in CoFe2O4. • No change of metallic valence state under dense electronic excitation. • Size independent control of cations in CoFe2O4. - Abstract: Present work investigates electronic excitation induced cationic exchange phenomena in nano-sized cobalt ferrites using Mössabaur and X-ray absorption spectroscopies. The electronic excitations were produced by irradiation of 100 MeV O+7 at different fluences ranging from 1 × 1011 to 1 × 1014 ions/cm2. Cubic spinel phase of cobalt ferrite remains preserved after irradiation. However, attributes of crystalline disorder were observed in irradiated materials. Crystallite size remain almost same for pristine and irradiated materials. X-ray absorption fine structure measurements show the preservation of valence state and spin state of metal ions under intense electronic excitation. These measurements also envisage bond breaking process induced by the electronic excitation. Mössbauer spectroscopic measurements also corroborate with the fine structure measurements that the valence state of Fe remains same after irradiation. Paramagnetic doublet which presents in the Mössabaur spectrum of pristine material disappears after irradiation, showing the evolution of irradiation induced magnetic ordering. Fe3+ ion increases with irradiation at octahedral site of spinel lattice. Magnetization of the material slightly increases after irradiation at the fluence of 5 × 1013 and 1 × 1014 ions/cm2

  15. Cation Exchange Strategy for the Encapsulation of a Photoactive CO-Releasing Organometallic Molecule into Anionic Porous Frameworks.

    Science.gov (United States)

    Carmona, Francisco J; Rojas, Sara; Sánchez, Purificación; Jeremias, Hélia; Marques, Ana R; Romão, Carlos C; Choquesillo-Lazarte, Duane; Navarro, Jorge A R; Maldonado, Carmen R; Barea, Elisa

    2016-07-01

    The encapsulation of the photoactive, nontoxic, water-soluble, and air-stable cationic CORM [Mn(tacn)(CO)3]Br (tacn = 1,4,7-triazacyclononane) in different inorganic porous matrixes, namely, the metalorganic framework bio-MOF-1, (NH2(CH3)2)2[Zn8(adeninate)4(BPDC)6]·8DMF·11H2O (BPDC = 4,4'-biphenyldicarboxylate), and the functionalized mesoporous silicas MCM-41-SO3H and SBA-15-SO3H, is achieved by a cation exchange strategy. The CO release from these loaded materials, under simulated physiological conditions, is triggered by visible light. The results show that the silica matrixes, which are unaltered under physiological conditions, slow the kinetics of CO release, allowing a more controlled CO supply. In contrast, bio-MOF-1 instability leads to the complete leaching of the CORM. Nevertheless, the degradation of the MOF matrix gives rise to an enhanced CO release rate, which is related to the presence of free adenine in the solution. PMID:27291890

  16. Enhanced photocatalytic activity of chromium(VI) reduction and EDTA oxidization by photoelectrocatalysis combining cationic exchange membrane processes

    International Nuclear Information System (INIS)

    Highlights: ► Chromium(VI) reduction and EDTA oxidization were conducted by photoelectrocatalysis. ► Apply the concept of cationic exchange membrane to enhance the conversion efficiency. ► The optimum TiO2 loading of 1 g/L was observed at acidic pH with current density 4 mA/cm2. ► Transformation pathway of EDTA was determined from analyzed byproducts and molecular orbital package analysis. -- Abstract: A novel technology of photoelectrocatalysis (PEC) combining with cationic exchange membrane (CEM) was proposed for simultaneous reduction of chromium(VI) and oxidization of EDTA. The application of CEM was used to enhance the efficiency for prevention of the re-oxidation of reduced chromium with the electron–hole pairs. In this study, effects of current density, pH, TiO2 dosage, hydraulic retention time (HRT), light intensity and EDTA/Cr(VI) molar ratio were all investigated. The results showed that the optimum conversion efficiency occurred at 4 mA/cm2 with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged Ti-OH2+, and negatively charged Cr(VI) and EDTA. The optimum TiO2 loading of 1 g/L was depended mainly on the acidic pH range, especially at higher HRT and irradiation intensity. In addition, higher EDTA/Cr(VI) molar ratio enhanced the reduction efficiency of Cr(VI), indicating EDTA plays the role of hole scavenger in this system. Moreover, incomplete EDTA decomposition contributes to the occurrence of intermediates, including nitrilotriacetic acid, iminodiacetic acid, glycine, oxamic acid, lyoxylic acid, oxalic acid, acetic acid and formic acid, as identified by GC/MS. Consequently, transformation pathway was determined from these analyzed byproducts and molecular orbital package analysis

  17. Advance chromatin extraction enhances performance and productivity of cation exchange chromatography-based capture of Immunoglobulin G monoclonal antibodies.

    Science.gov (United States)

    Nian, Rui; Gagnon, Pete

    2016-07-01

    The impact of host cell-derived chromatin was investigated on the performance and productivity of cation exchange chromatography as a method for capture-purification of an IgG monoclonal antibody. Cell culture supernatant was prepared for loading by titration to pH 6.0, dilution with water to a conductivity of 4mS/cm, then microfiltration to remove solids. DNA content was reduced 99% to 30ppm, histone host cell protein content by 76% to 6300ppm, non-histone host cell protein content by 15% to 321,000ppm, and aggregates from 33% to 15%. IgG recovery was 83%. An alternative preparation was performed, adding octanoic acid, allantoin, and electropositive particles to the harvest at pH 5.3, then removing solids. DNA content was reduced to<1 ppb, histones became undetectable, non-histones were reduced to 24,000ppm, and aggregates were reduced to 2.4%. IgG recovery was 95%. This treatment increased dynamic capacity (DBC) of cation exchange capture to 173g/L and enabled the column to reduce non-histone host proteins to 671ppm. Step recovery was 99%. A single multimodal polishing step further reduced them to 15ppm and aggregates to <0.1%. Overall process recovery was 89%. Productivity at feed stream IgG concentrations of 5-10g/L was roughly double the productivity of a same-size protein A column with a DBC of 55g/L. PMID:27247214

  18. Enhanced photocatalytic activity of chromium(VI) reduction and EDTA oxidization by photoelectrocatalysis combining cationic exchange membrane processes

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hung-Te, E-mail: der11065@hotmail.com [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Chen, Shiao-Shing, E-mail: f10919@ntut.edu.tw [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Tang, Yi-Fang, E-mail: sweet39005@hotmail.com [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Hsi, Hsing-Cheng, E-mail: hchsi@ntut.edu.tw [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China)

    2013-03-15

    Highlights: ► Chromium(VI) reduction and EDTA oxidization were conducted by photoelectrocatalysis. ► Apply the concept of cationic exchange membrane to enhance the conversion efficiency. ► The optimum TiO{sub 2} loading of 1 g/L was observed at acidic pH with current density 4 mA/cm{sup 2}. ► Transformation pathway of EDTA was determined from analyzed byproducts and molecular orbital package analysis. -- Abstract: A novel technology of photoelectrocatalysis (PEC) combining with cationic exchange membrane (CEM) was proposed for simultaneous reduction of chromium(VI) and oxidization of EDTA. The application of CEM was used to enhance the efficiency for prevention of the re-oxidation of reduced chromium with the electron–hole pairs. In this study, effects of current density, pH, TiO{sub 2} dosage, hydraulic retention time (HRT), light intensity and EDTA/Cr(VI) molar ratio were all investigated. The results showed that the optimum conversion efficiency occurred at 4 mA/cm{sup 2} with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged Ti-OH{sub 2}{sup +}, and negatively charged Cr(VI) and EDTA. The optimum TiO{sub 2} loading of 1 g/L was depended mainly on the acidic pH range, especially at higher HRT and irradiation intensity. In addition, higher EDTA/Cr(VI) molar ratio enhanced the reduction efficiency of Cr(VI), indicating EDTA plays the role of hole scavenger in this system. Moreover, incomplete EDTA decomposition contributes to the occurrence of intermediates, including nitrilotriacetic acid, iminodiacetic acid, glycine, oxamic acid, lyoxylic acid, oxalic acid, acetic acid and formic acid, as identified by GC/MS. Consequently, transformation pathway was determined from these analyzed byproducts and molecular orbital package analysis.

  19. Controlling electron beam-induced structure modifications and cation exchange in cadmium sulfide–copper sulfide heterostructured nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Haimei [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sadtler, Bryce; Habenicht, Carsten [Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Freitag, Bert [FEI Company, P.O. Box 80066, KA 5600 Eindhoven (Netherlands); Alivisatos, A. Paul [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Kisielowski, Christian, E-mail: CFKisielowski@lbl.gov [National Center for Electron Microcopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Joint Center for Artificial Photosynthesis, Berkeley, CA 94720 (United States)

    2013-11-15

    The atomic structure and interfaces of CdS/Cu{sub 2}S heterostructured nanorods are investigated with the aberration-corrected TEAM 0.5 electron microscope operated at 80 kV and 300 kV applying in-line holography and complementary techniques. Cu{sub 2}S exhibits a low-chalcocite structure in pristine CdS/Cu{sub 2}S nanorods. Under electron beam irradiation the Cu{sub 2}S phase transforms into a high-chalcocite phase while the CdS phase maintains its wurtzite structure. Time-resolved experiments reveal that Cu{sup +}–Cd{sup 2+} cation exchange at the CdS/Cu{sub 2}S interfaces is stimulated by the electron beam and proceeds within an undisturbed and coherent sulfur sub-lattice. A variation of the electron beam current provides an efficient way to control and exploit such irreversible solid-state chemical processes that provide unique information about system dynamics at the atomic scale. Specifically, we show that the electron beam-induced copper–cadmium exchange is site specific and anisotropic. A resulting displacement of the CdS/Cu{sub 2}S interfaces caused by beam-induced cation interdiffusion equals within a factor of 3–10 previously reported Cu diffusion length measurements in heterostructured CdS/Cu{sub 2}S thin film solar cells with an activation energy of 0.96 eV. - Highlights: • Heterostructured nanorods were investigated at atomic resolution showing that they are free of extended defects. • Beam–sample interactions are controlled by current and voltage variations to provide pristine crystal structures. • Beam-induced migration of heterointerfaces are measured time-resolved and compared with Cu diffusion coefficients. • Beam–sample interaction overwrite possible signal improvements that can be expected by sample cooling.

  20. Physical characterization of the state of motion of the phenalenyl spin probe in cation-exchanged faujasite zeolite supercages with pulsed EPR

    Science.gov (United States)

    Doetschman, D. C.; Dwyer, D. W.; Fox, J. D.; Frederick, C. K.; Scull, S.; Thomas, G. D.; Utterback, S. G.; Wei, J.

    1994-08-01

    The molecular motion of the phenalenyl (PNL) spin probe in the supercages of cation-exchanged X and Y zeolites (faujasites) has been physically characterized by pulsed and continuous wave (CW) electron paramagnetic resonance (EPR). Both X and Y zeolites, whose cation sites were exchanged with the alkali metal ions, Li +, Na +, K +, Rb + and Cs + were examined. There is a good correspondence between the temperature dependences of the PNL electron spin phase memory time and the CW EPR spectra. Both display evidence of a thermal activation from a stationary, non-rotating molecular state to a low-temperature state of in-plane rotation (Das et al., Chem Phys. 143 (1990) 253). The rate of in-plane rotation is an activated process, with E* | / R=1289 |+- 35 K and 1462 ± 47 K in NaX and KX zeolites, respectively. The rotation appears to be about an axis along which the half-filled, non-bonding π orbital interacts with the exchanged cation in the supercage. Both CW and pulsed EPR also show a higher temperature activation from the in-plane rotating state to an effectively isoptropic state of rotation of PNL in which the PNL-cation bond is thought to be broken, with E* ⊥ / R=2050 ± 110 K, 1956 ± 46K, 1335 ± 97 K in LiX, NaX and KX zeolites, respectively. The strength of the PNL-cation bonding decreases with increasing cation atomic number as indicated by E* ⊥ and the peripheral repulsion (crowding) of PNL increases with cation size as indicated E* |. There are qualitative indications that the binding of PNL to the cations in the Y zeolite is stronger than in the X zeolite.

  1. Structure and resistance of concentration polar layer on cation exchange membrane-solution interface

    Institute of Scientific and Technical Information of China (English)

    SANG Shang-bin; HUANG Ke-long; LI Xiao-gang; WANG Xian

    2006-01-01

    Membrane/solution interface consists of a neutral concentration polar layer(CPL) and a charge layer(CL) under external electrical field, and the neutral CPL can be neglected under high frequency AC electrical field. The relationship of CL thickness e with electrolyte concentration C and fixed ion exchange sites density σ in membrane surface layer can be expressed as e=σ/C.According to this model, the thickness of the CL on Nafion1135 membrane/solution interface(ec) was calculated under different membrane surface charge quantity Q and variable electrolyte concentration C. The membrane/solution interface CL thickness(em) is obviously related with the membrane properties, and decreases dramatically in a higher electrolyte concentration, em values are 76.3nm and 110.3 nm respectively for Nafion1135 and PE01 ion exchange membrane in 0.05 mol/L H2SO4 solution, and em values for both membrane tend to 2 nm in 2 mol/L H2SO4 solution. For Nafion1135 membrane, the comparison of ec and em gives the result that CL thickness em obtained by resistance measurement fits well with the calculated CPL thickness ec while proton in CL transferred to membrane surface is 14.56 × l0-10 mol, which corresponds to the fixed exchange group number in a surface layer with a thickness τ=2 nm for Nafion1135 membrane.

  2. Post-transfusion purpura treated with plasma exchange by haemonetics cell separator. A case report

    DEFF Research Database (Denmark)

    Laursen, B; Morling, N; Rosenkvist, J;

    1978-01-01

    A case of post-transfusion purpura in a 61-year-old, multiparous female with a platelet alloantibody (anti-Zwa) in her serum is reported. The patient was successfully treated with plasma exchange by means of a Haemonetics 30 cell separator and corticosteroids. Compared with other therapeutic...... measures, plasma exchange seems to shorten the duration of thrombocytopenia. Major surgery was possible in our patient within ten days of development of the syndrome....

  3. Intensification of heat and mass transfer by ultrasound: application to heat exchangers and membrane separation processes.

    Science.gov (United States)

    Gondrexon, N; Cheze, L; Jin, Y; Legay, M; Tissot, Q; Hengl, N; Baup, S; Boldo, P; Pignon, F; Talansier, E

    2015-07-01

    This paper aims to illustrate the interest of ultrasound technology as an efficient technique for both heat and mass transfer intensification. It is demonstrated that the use of ultrasound results in an increase of heat exchanger performances and in a possible fouling monitoring in heat exchangers. Mass transfer intensification was observed in the case of cross-flow ultrafiltration. It is shown that the enhancement of the membrane separation process strongly depends on the physico-chemical properties of the filtered suspensions.

  4. Spin-electron acoustic soliton and exchange interaction in separate spin evolution quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, Pavel A., E-mail: andreevpa@physics.msu.ru [Faculty of Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

    2016-01-15

    Separate spin evolution quantum hydrodynamics is generalized to include the Coulomb exchange interaction, which is considered as interaction between the spin-down electrons being in quantum states occupied by one electron. The generalized model is applied to study the non-linear spin-electron acoustic waves. Existence of the spin-electron acoustic soliton is demonstrated. Contributions of concentration, spin polarization, and exchange interaction to the properties of the spin electron acoustic soliton are studied.

  5. Heat-Activated Effect of Exchange Coupling Between Two Ferromagnets Separated by an Amorphous Semiconducting Barrier

    Institute of Scientific and Technical Information of China (English)

    肖明文; 李正中; 许望

    2002-01-01

    We try to extend our previous zero-temperature tunnelling theory for the exchange coupling between two ferromagnets separated by an amorphous semiconducting barrier to the case of finite temperature. The result exhibits that the tunnelling electrons can absorb or emit phonons when they tunnel through the amorphous barrier at finite temperatures so that the interlayer exchange coupling is heat activated. This agrees with the experiments.

  6. Continuous Separation of Cesium Based on NiHCF/PTCF Electrode by Electrochemically Switched Ion Exchange

    Institute of Scientific and Technical Information of China (English)

    孙斌; 郝晓刚; 王忠德; 张忠林; 刘世斌; 官国清

    2012-01-01

    Nickel hexacyanoferrate (NiHCF) film was synthesized on porous three-dimensional carbon felt (PTCF) substrate by repetitious batch chemical depositions, and the NiHCF/PTCF electrode was used as electrochemically switched ion exchange (ESIX) electrode in a packed bed for continuous separation for cesium ions. The morphologies of the prepared electrodes were characterized by scanning electron microscopy and the effects of solution concentration on the ion-exchange capacity of the electrodes were investigated by cyclic voltammetry technique. Cycling stability and long-term storage stability of NiHCF/PTCF electrodes were also studied. The NiHCF/PTCF electrodes with excellent ion-exchange ability were used to assemble a diaphragm-isolated ESIX reactor for cesium separation. Continuous separation of cesium and regeneration of NiHCF/PTCF electrode based on the diaphragm-isolated reactor were performed in a laboratory-scale two-electrode system.

  7. Mathematical modeling of salt-gradient ion-exchange simulated moving bed chromatography for protein separations

    Institute of Scientific and Technical Information of China (English)

    卢建刚

    2004-01-01

    The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-exchange equilibrium, salt gradient, size exclusion, mass transfer resistance, and port periodic switching mechanism, was developed to simulate the complex dynamics. The model predictions were verified by the experimental data on upward and downward gradients for protein separations reported in the literature. All design and operating parameters (number, configuration, length and diameter of columns, particle size, switching period, flow rates of feed, raffinate, desorbent and extract, protein concentrations in feed, different salt concentrations in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale-up of salt-gradient ion-exchange SMBC for protein separations.

  8. 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)

  9. Determination of rare-earth elements in geological materials by ion-exchange chromatography separation and induction coupled plasma emission spectroscopy

    International Nuclear Information System (INIS)

    A methodology for the analysis of Rare-Earth elements in geological samples has been developed. Ion exchange chromatography for the separation and induction coupled plasma emission spectroscopy for the analysis have been used. The columns with cationic resin were calibrated with radioactive elements. With complexes matrices, the instrument's data must be corrected for the presence of majors elements (CEM) and for the interferences of the Rare-earth elements (CETR). The accuracy and precision are evaluated critically with respect to the convenience and efficiency of this methodology in the analysis of rare-Earth elements i geological samples. (author)

  10. Separation of hydrogen isotopes by exchange reaction between water and hydrogen using hydrophobic platinum catalyst

    International Nuclear Information System (INIS)

    The case of utilizing exchange reaction and distillation has been found very frequently in practical scale in the separation process of hydrogen isotopes such as heavy water and deuterium. Distillation consumes a large quantity of energy, but it is a promising method in future because of the stability and simplicity of the process utilizing phase equilibrium. In the exchange reaction method, there are four excellent reactions involving the exchange reaction between gas and liquid, and in the practical process, counter flow gas-liquid contact towers are used. In this case, single temperature exchange method and double temperature exchange method are conceivable. In order to prevent the condensation of water molecules on active platinum surface, the catalyst has been made hydrophobic. The evaluation of catalyst activity and its basic theory, the lowering of catalyst activity and the effect of regeneration, the rate of exchange reaction and activation energy, and overall mass transfer coefficient are discussed. The performance of hydrogen isotope separation in a counter flow type exchange tower is represented by two factors in gas and liquid phase reactions, and to improve the performance, the transfer at gas-liquid interface must be accelerated, (Kako, I.)

  11. Purification of recombinant aprotinin produced in transgenic corn seed: separation from CTI utilizing ion-exchange chromatography

    Directory of Open Access Journals (Sweden)

    A. R. Azzoni

    2005-09-01

    Full Text Available Protein expression in transgenic plants is considered one of the most promising approaches for producing pharmaceutical proteins. As has happened with other recombinant protein production schemes, the downstream processing (dsp of these proteins produced in plants is key to the technical and economic success of large-scale applications. Since dsp of proteins produced transgenically in plants has not been extensively studied, it is necessary to broaden the investigation in this field in order to more precisely evaluate the commercial feasibility of this route of expression. In this work, we studied the substitution of an IMAC chromatographic step, described in previous work (Azzoni et al., 2002, with ion-exchange chromatography on SP Sepharose Fast Flow resin as the second step in the purification of recombinant aprotinin from transgenic maize seed. The main goal of this second purification step is to separate the recombinant aprotinin from the native corn trypsin inhibitor. Analysis of the adsorption isotherms determined at 25°C under different conditions allowed selection of 0.020 M Tris pH 8.5 as the adsorption buffer. The cation-exchange chromatographic process produced a high-purity aprotinin that was more than ten times more concentrated than that generated using an IMAC step.

  12. The removal of radioactive radium (Ra226) from chloride liquors by columnar ion exchange in the presence of calcium, magnesium and iron cations

    International Nuclear Information System (INIS)

    The purpose of this work was to study the feasibility of controlling the discharge of soluble Ra226, in the presence of Ca, Mg and Fe cations in synthetic chloride effluents, by adsorption on cation exchange resins to decrease Ra226-concentrations to federal environmental levels of 10 pCi Ra226/litre. Environmentally acceptable effluents were produced from synthetic chloride feed liquors containing 10 ppm Ca, 5 ppm Mg, 120 ppm Fe plus 20,000 pCi Ra226/litre. Environmentally acceptable effluents were not produced, by cation exchange, from a synthetic chloride liquor containing 490 ppm Ca, 97 ppm Mg, 720 ppm Fe in addition to 20,000 pCi Ra226/litre. The mass interference of the Ca + Mg + Fe cation concentrations in the feed liquor was in over-powering competition, for resin sites, with the Ra226-cations. To obtain realistic data, the adsorption process should be reexamined using a chloride liquor produced under optimal chloride leaching conditions of an Elliot Lake uranium ore. This would, in all probability, reveal other cations unavailable in the synthetic chloride liquors

  13. Copper removal and nickel for exchange cationic with a natural zeolite

    International Nuclear Information System (INIS)

    Natural zeolite clinoptilolite, was used to remove copper and nickel from waste waters of a galvanotechnical company. Exchange capacity determined for the zeolite after its transformation to homoionic sodium form, was 0.794 meq/g for copper and 0.447 meq/g for nickel. There were made batch and column experiments, reaching the last one a better approach to the equilibrium. From the degeneration essays, the sodical zeolite concentrates the copper in the waste waters to 23.5 up times the level found for the acid rinsing waters; it shows its potential use in treatment of these waste, because its effectiveness and low cost

  14. Disintegration and dissolution of spent radioactive cationic exchange resins using Fenton-like oxidation process

    International Nuclear Information System (INIS)

    Highlights: • The spent radioactive resins could be oxidized by Fenton-like process. • The influencing factors on resin oxidation were evaluated. • Chemical oxygen demand (COD) reduction rate was more than 99%. • SEM and Raman spectrum were used to analyze the resins morphological change. - Abstract: The treatment and disposal of the spent radioactive resins is essential for the sustainable development of the nuclear industry. In this paper, the disintegration and dissolution of spent cationic resins were studied by Fenton-like process. The influencing factors on resin dissolution, such as pH, temperature, type and concentration of catalysts were evaluated. The results showed that the spent resins could be effectively dissolved at pH < 1, [Fe2+] = 0.2 M and T = 97 ± 2 °C. Chemical oxygen demand (COD) reduction rate was more than 99%. The scanning electron microscopy and the Raman spectrum were used to observe the morphological changes of the spent resins during the dissolution process. Fenton-like oxidation is an efficient method for the volume reduction and stabilization of the spent resins before further immobilization

  15. Disintegration and dissolution of spent radioactive cationic exchange resins using Fenton-like oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Zhong; Xu, Lejin [Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084 (China); Wang, Jianlong, E-mail: wangjl@tsinghua.edu.cn [Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084 (China); Beijing Key Laboratory of Radioactive Wastes Treatment, Tsinghua University, Beijing 100084 (China)

    2015-09-15

    Highlights: • The spent radioactive resins could be oxidized by Fenton-like process. • The influencing factors on resin oxidation were evaluated. • Chemical oxygen demand (COD) reduction rate was more than 99%. • SEM and Raman spectrum were used to analyze the resins morphological change. - Abstract: The treatment and disposal of the spent radioactive resins is essential for the sustainable development of the nuclear industry. In this paper, the disintegration and dissolution of spent cationic resins were studied by Fenton-like process. The influencing factors on resin dissolution, such as pH, temperature, type and concentration of catalysts were evaluated. The results showed that the spent resins could be effectively dissolved at pH < 1, [Fe{sup 2+}] = 0.2 M and T = 97 ± 2 °C. Chemical oxygen demand (COD) reduction rate was more than 99%. The scanning electron microscopy and the Raman spectrum were used to observe the morphological changes of the spent resins during the dissolution process. Fenton-like oxidation is an efficient method for the volume reduction and stabilization of the spent resins before further immobilization.

  16. 阳离子树脂净化铂族金属溶液的研究%Purification of Platinum Group Metals Solution by Cation Exchange

    Institute of Scientific and Technical Information of China (English)

    毕向光; 余建民; 杨金富; 贺洪亮; 李权

    2015-01-01

    研究了阳离子交换树脂净化含大量贱金属的铂族金属溶液的工艺条件,结果表明,在pH=1~1.5时001×7阳离子交换树脂吸附贱金属的次序为:Ni>Cu>Co>Fe;Fe、Ni、Co、Cu的穿透容量分别为(g/kg):0.13,1.25,0.42,0.87;饱和容量分别为(g/kg):0.32,6.65,2.33,4.72,合计为14.02 g/kg;贱金属的分离效率主要取决于贵贱金属浓度及交换柱的数量;吸附在树脂上的贱金属极易被6 mol/L HCl洗脱,所有贱金属的最大洗脱均发生在洗脱液体积与床体积之比为1.0/1.7处,当洗脱液体积为床体积的2.0倍时贱金属被完全洗脱。实验结果为离子交换分离贱金属净化铂族金属溶液的工业化应用提供了强有力的理论依据。%The platimum group metals ( PGMs) solution containing a large amount of base metals purified with cation exchange resin had been investigated. The results showed that the adsorption of base metals by 001 × 7 cation ion exchange resin at pH=1~1.5 was in the order of Ni>Cu>Co>Fe. From the tests, the breakthrough capacities ( g/kg) of Fe, Ni, Co and Cu were 0.13, 1.25, 0.42 and 0.87, respectively, while the saturated capacities ( g/kg) were 0.32, 6.65, 2.33 and 4.72, respectively and 14.02 g/kg in total. It is shown that the separation efficiency of the base metals depends largely on the concentrations of the precious and base metals, as well as the number of exchange columns. The base metals absorbed on the resin could be easily eluted by adding HCl solution at the amount of 6 mol/L, with the elution reaching the maximum as the eluent volume and bed volume at the ratio of 1.0/1.7 and completely finished as the eluent volume being 2. 0 times the bed volume. The experimental results can definitely provide a theoretical basis favorably for the industrial application of PGMs solution purified by cation exchange resin.

  17. Acceptable levels of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in soils, depending on their clay and humus content and cation-exchange capacity

    NARCIS (Netherlands)

    Haan, de S.; Rethfeld, H.; Driel, van W.

    1985-01-01

    Three sandy soils differing in humus content and three clay soils differing in clay content were supplied with heavy metals to determine which loading rate of each single metal should be regarded as critical from the viewpoint of crop yield and metal content dependent on soil cation exchange capacit

  18. Increased selectivity for planar chromatography by ion exchange : cation chromatography on papers impregnated with titanium (IV) based inorganic ion exchangers in DMSO-HNO3 mobile phases

    International Nuclear Information System (INIS)

    Planar chromatography of thirty six metal ions on titanium(IV) phosphate, titanium(IV) tungstate and titanium(IV) molybdate impregnated papers in DMSO-HNO3 mobile phases has been carried out. The ion-exchange capacity of papers is determined and the effects of solvent composition, impregnation and pH on RF values are studied. For K+, Rb+ and Cs+, RF = KC1/2, where C is the nitric acid concentration. The movement of ions is explained on the basis of ion-exchange, adsorption and precipitation. Alberti and Torracca's view for the prediction of elution sequence from RF values has been checked. The sequence of adsorption of ions follows the order : titanium(IV) molybdate > titanium(IV) tungstate > titanium(IV) phosphate. Some of the analytically important separations are reported. (author)

  19. Triple-channel portable capillary electrophoresis instrument with individual background electrolytes for the concurrent separations of anionic and cationic species.

    Science.gov (United States)

    Mai, Thanh Duc; Le, Minh Duc; Sáiz, Jorge; Duong, Hong Anh; Koenka, Israel Joel; Pham, Hung Viet; Hauser, Peter C

    2016-03-10

    The portable capillary electrophoresis instrument is automated and features three independent channels with different background electrolytes to allow the concurrent optimized determination of three different categories of charged analytes. The fluidic system is based on a miniature manifold which is based on mechanically milled channels for injection of samples and buffers. The planar manifold pattern was designed to minimize the number of electronic valves required for each channel. The system utilizes pneumatic pressurization to transport solutions at the grounded as well as the high voltage side of the separation capillaries. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 (w) × 35 (d) × 15 cm (h) and a weight of about 15 kg. It can operate continuously for 8 h in the battery-powered mode if only one electrophoresis channel is in use, or for about 2.5 h in the case of simultaneous employment of all three channels. The different operations, i.e. capillary flushing, rinsing of the interfaces at both capillary ends, sample injection and electrophoretic separation, are activated automatically with a control program featuring a graphical user interface. For demonstration, the system was employed successfully for the concurrent separation of different inorganic cations and anions, organic preservatives, additives and artificial sweeteners in various beverage and food matrices. PMID:26893094

  20. Comparing Nafion and ceramic separators used in electrochemical purification of spent chromium plating solutions: cationic impurity removal and transport.

    Science.gov (United States)

    Huang, Kuo-Lin; Holsen, Thomas M; Chou, Tse-Chuan; Selman, J Robert

    2003-05-01

    This study focuses on the electrolytic regeneration of spent chromium plating solutions. These solutions contain a significant amount of chromium and a lesser amount of other heavy metals, which makes them a significant environmental concern and an obvious target for recycling and reuse. The type of separator used is extremely critical to the performance of the process because they are the major resistance in the transport-related impurity (Cu(II), Ni(II), and Fe(III)) removals from contaminated chromic acid solutions. A Nafion 117 membrane and a ceramic diaphragm separator traditionally used in the industry were tested for comparison. It was found that the mobilities of Cu(II) and Ni(II) were similar and higher than that of Fe(III) using both separators. The mobility of each cation was smaller in the Nafion membrane than in the ceramic diaphragm. The measured conductivity of the ceramic diaphragm was slightly higher than that of Nafion membrane. However, the Nafion membrane was much thinner than the ceramic diaphragm resulting in the system using the Nafion membrane having higher impurity removal rates than the system using the ceramic diaphragm. The removal rates were approximately equal for Cu(II) and Ni(II) and lowest for Fe(III). Both current and initial concentration affected the removal rates of the impurities. Modeling results indicated that a system using a Nafion separator and a small catholyte/anolyte volume ratio was better than a system using a ceramic separator for removing impurities from concentrated plating solutions if the impurities transported into the catholyte are deposited or precipitated. PMID:12775076

  1. Selective separation of beta-lactoglobulin from sweet whey using CGAs generated from the cationic surfactant CTAB.

    Science.gov (United States)

    Fuda, Elisabeth; Bhatia, Divesh; Pyle, D L; Jauregi, Paula

    2005-06-01

    The selective separation of whey proteins was studied using colloidal gas aphrons generated from the cationic surfactant cetyl trimethyl ammonium bromide (CTAB). From the titration curves obtained by zeta potential measurements of individual whey proteins, it was expected to selectively adsorb the major whey proteins, i.e., bovine serum albumin, alpha-lactalbumin, and beta-lactoglobulin to the aphrons and elute the remaining proteins (lactoferrin and lactoperoxidase) in the liquid phase. A number of process parameters including pH, ionic strength, and mass ratio of surfactant to protein (M(CTAB)/M(TP)) were varied in order to evaluate their effect on protein separation. Under optimum conditions (2 mmol/l CTAB, M(CTAB)/M(TP) = 0.26-0.35, pH 8, and ionic strength = 0.018 mol/l), 80-90% beta-lactoglobulin was removed from the liquid phase as a precipitate, while about 75% lactoferrin and lactoperoxidase, 80% bovine serum albumin, 95% immunoglobulin, and 65% alpha-lactalbumin were recovered in the liquid fraction. Mechanistic studies using zeta potential measurements and fluorescence spectroscopy proved that electrostatic interactions modulate only partially the selectivity of protein separation, as proteins with similar surface charges do not separate to the same extent between the two phases. The selectivity of recovery of beta-lactoglobulin probably occurs in two steps: the first being the selective interaction of the protein with opposite-charged surfactant molecules by means of electrostatic interactions, which leads to denaturation of the protein and subsequent formation and precipitation of the CTAB-beta-lactoglobulin complex. This is followed by the separation of CTAB-beta-lactoglobulin aggregates from the bulk liquid by flotation in the aphron phase. In this way, CGAs act as carriers which facilitate the removal of protein precipitate. PMID:15816026

  2. Separation of selected stable isotopes by liquid-phase thermal diffusion and by chemical exchange

    International Nuclear Information System (INIS)

    Useful applications of enriched stable nuclides are unduly restricted by high cost and limited availability. Recent research on liquid phase thermal diffusion (LTD) has resulted in practical processes for separating 34S, 35Cl, and 37Cl in significant quantities (100 to 500 g/yr) at costs much lower than those associated with the electromagnetic (Calutron) process. The separation of the isotopes of bromine by LTD is now in progress and 79Br is being produced in relatively simple equivalent at a rate on the order of 0.5 g/day. The results of recent measurements show that the isotopes of Zn can be separated by LTD of zinc alkyls. The isotopes of calcium can be separated by LTD and by chemical exchange. The LTD process is based on the use of aqueous Ca(NO3)2 as a working fluid. The chemical exchange method involves isotopically selective exchange between an aqueous phase containing a calcium salt and an organic phase containing calcium in the form of a complex with a macrocyclic ligand. The LTD method is suitable for high enrichments at low through-puts; whereas, the chemical exchange techniques is appropriate for lower enrichments at much higher production rates. Current research is directed toward reducing these concepts to practical processes

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

    Science.gov (United States)

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

    2007-01-01

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

  4. Separation of the rare earths by anion-exchange in the presence of lactic acid

    Science.gov (United States)

    Faris, J. P.

    1969-01-01

    Investigation of adsorption of rare earths and a few other elements to an anion-exchange resin from mixed solvents containing lactic acid shows that the lanthanides are absorbed more strongly than from the alpha-hydroxyisobutryric acid system, but with less separation between adjacent members of the series.

  5. High-purity isolation of anthocyanins mixtures from fruits and vegetables--a novel solid-phase extraction method using mixed mode cation-exchange chromatography.

    Science.gov (United States)

    He, Jian; Giusti, M Monica

    2011-11-01

    Research on biological activity of anthocyanins requires the availability of high purity materials. However, current methods to isolate anthocyanins or anthocyanin mixtures are tedious and expensive or insufficient for complete isolation. We applied a novel cation-exchange/reversed-phase combination solid-phase extraction (SPE) technique, and optimized the use of water/organic buffer mobile phases to selectively separate anthocyanins. Crude extracts of various representative anthocyanin sources were purified with this technique and compared to 3 commonly used SPE techniques: C(18), HLB, and LH-20. Purified anthocyanin fractions were analyzed with high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) and mass spectrometry (MS) detectors and by Fourier transform infrared (FT-IR) spectroscopy. The UV-visible chromatograms quantitatively demonstrated that our novel technique achieved significantly higher (Pmethod, for 11 of the 12 anthocyanin sources tested. Among them, eight were purified to greater than 99% purity (based on UV-visible chromatograms). The new method efficiently removed non-anthocyanin phenolics. MS and FT-IR results semi-quantitatively confirmed extensive reduction of impurities. Due to strong ionic interaction, our sorbent capacity was superior to others, resulting in the highest throughput and least use of organic solvents. This new methodology for isolation of anthocyanin mixtures drastically increased purity and efficiency while maintaining excellent recovery rate and low cost. The availability of high purity anthocyanin mixtures will facilitate anthocyanin studies and promote the application of anthocyanins in the food and nutraceutical industries. PMID:21968344

  6. Isolation of cross-linked peptides by diagonal strong cation exchange chromatography for protein complex topology studies by peptide fragment fingerprinting from large sequence databases.

    Science.gov (United States)

    Buncherd, Hansuk; Roseboom, Winfried; Ghavim, Behrad; Du, Weina; de Koning, Leo J; de Koster, Chris G; de Jong, Luitzen

    2014-06-27

    Knowledge of spatial proximity of amino acid residues obtained by chemical cross-linking and mass spectrometric analysis provides information about protein folding, protein-protein interactions and topology of macromolecular assemblies. We show that the use of bis(succinimidyl)-3-azidomethyl glutarate as a cross-linker provides a solution for two major analytical problems of cross-link mapping by peptide fragment fingerprinting (PFF) from complex sequence databases, i.e., low abundance of protease-generated target peptides and lack of knowledge of the masses of linked peptides. Tris(carboxyethyl)phosphine (TCEP) reduces the azido group in cross-linked peptides to an amine group in competition with cleavage of an amide bond formed in the cross-link reaction. TCEP-induced reaction products were separated by diagonal strong cation exchange (SCX) from unmodified peptides. The relation between the sum of the masses of the cleavage products and the mass of the parent cross-linked peptide enables determination of the masses of candidate linked peptides. By reversed phase LC-MS/MS analysis of secondary SCX fractions, we identified several intraprotein and interprotein cross-links in a HeLa cell nuclear extract, aided by software tools supporting PFF from the entire human sequence database. The data provide new information about interacting protein domains, among others from assemblies involved in splicing.

  7. Design of a fixed-bed ion-exchange process for the treatment of rinse waters generated in the galvanization process using Laminaria hyperborea as natural cation exchanger.

    Science.gov (United States)

    Mazur, Luciana P; Pozdniakova, Tatiana A; Mayer, Diego A; Boaventura, Rui A R; Vilar, Vítor J P

    2016-03-01

    In this study, the removal of zinc from galvanization wastewaters was performed in a fixed bed column packed with brown macro-algae Laminaria hyperborea, acting as a natural cation exchanger (resin). The rinse wastewater presents a zinc concentration between 9 and 22 mg/L, a high concentration of light metals (mainly Na and Ca), a high conductivity (0.5-1.5 mS/cm) and a low organic content (DOC = 7-15 mg C/L). The zinc speciation diagram showed that approximately 80% of zinc is in the form of Zn(2+) and ≅20% as ZnSO4, considering the effluent matrix. From all operational conditions tested for zinc uptake (17 bed height<27 cm, 4.5 < flow rate<18.2 BV/h, 0.8 < particle equivalent diameter<2.0 mm), the highest useful capacity (7.1 mg Zn/g algae) was obtained for D/dp = 31, L/D = 11, 9.1 BV/h, τ = 6.4 min, corresponding to a service capacity of 124 BV (endpoint of 2 mg Zn/L). Elution was faster and near to 100% effective using 10 BV of HCl (1 M, 3.0%, 363 g HCl/L of resin), for flow rates higher than 4.5 BV/h. Calcium chloride solution (0.1 M) was selected as the best regenerant, allowing the reuse of the natural resin for more than 3 saturation/elution/regeneration cycles. The best operation conditions were scaled-up and tested in a pre-pilot plant. The scale-up design of the cation exchange process was proposed for the treatment of 2.4 m(3)/day of galvanization wastewater, resulting in an estimated reactants cost of 2.44 €/m(3). PMID:26766159

  8. Separation of Ra/Ca by ion exchange; Separacion de Ra/Ca por intercambio ionico

    Energy Technology Data Exchange (ETDEWEB)

    Iturbe, J.L.; Jimenez R, M.; Flores M, J

    1991-04-15

    The radium and the calcium belong to the same group in the periodic classification and as consequence both they present very similar chemical properties, that makes difficult its separation. Both elements are also frequently associate in the nature, the calcium is very abundant, the radium is not it and for that reason it is indispensable its separation to analyze to this last one. The alpha spectroscopy is very appropriate to analyze to the {sup 226} Ra, however to achieve a good resolution of the spectra, the samples should contain small quantities of calcium. The purposes of this work were to know the chromatographic behavior of the alkaline-earthy cations: calcium, barium and radium and to apply these knowledge to the separation of the {sup 226} Ra and its analysis by means of alpha spectroscopy. (Author)

  9. Modification of polyamide-CdS-CdSe composite material films with Ag using a cation–cation exchange reaction

    Energy Technology Data Exchange (ETDEWEB)

    Krylova, V.; Žalenkienė, S.; Dukstienė, N. [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu st. 19, LT-50254, Kaunas (Lithuania); Baltrusaitis, J., E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

    2015-10-01

    Highlights: • We investigated deposition of a mixed CdSe-CdS-Ag{sub 2}Se-Ag{sub 2}S on polyamide. • A single chalcogen precursor – K{sub 2}SeS{sub 2}O{sub 6} – was used. • AAS showed five- to ten-fold excess of chalcogens diffused into PA. • Addition of AgNO{sub 3} resulted in subsurface Ag{sub 2}Se–Ag{sub 2}S formation. - Abstract: Thin mixed CdSe-CdS-Ag{sub 2}Se-Ag{sub 2}S films were deposited on a polyamide 6 (PA) surface by successfully using a cation-exchange reaction between Cd{sup 2+} and Ag{sup +} to convert CdSe-CdS into Ag{sub 2}Se-Ag{sub 2}S. These were deposited using a K{sub 2}SeS{sub 2}O{sub 6} precursor solution at 60 °C followed by cadmium acetate (Cd(CH{sub 3}COO){sub 2}). An aqueous AgNO{sub 3} solution was used as the Ag source. XRD patterns showed a complex PA-Cd-S-Se-Ag film crystalline composition with CdS, CdSe, Ag{sub 2}S and Ag{sub 2}Se peaks. Calculated dislocation density ranged within 5–15 × 10{sup 13} lines·m{sup −2} indicating high quality atomic layers. Atomic Absorption Spectroscopy (AAS) showed five- to ten-fold excess of chalcogens to metals in the thin films formed. No chalcogenides were observed on the sample surface during XPS analysis after Ag exchange due to the desorption of CdS and CdSe layers, not diffused into the bulk of the polymer suggesting that silver chalcogenides were located subsurface, as opposed to the outermost layer, likely comprised of Ag{sub 2}O.

  10. Synthesis and characterization of a novel hybrid nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate: Its analytical applications as ion-selective electrode

    Science.gov (United States)

    Khan, Asif Ali; Shaheen, Shakeeba

    2013-02-01

    A novel organic-inorganic nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate has been synthesized by incorporation of a polymer material into inorganic precipitate. The material is a class of hybrid ion-exchanger with good ion-exchange properties, reproducibility, stability and good selectivity for heavy metals. The physico-chemical properties of this nano composite material were characterized by using XRD, TGA, FTIR, SEM and TEM. The ion-exchange capacity, pH titrations, elution behavior and chemical stability were also carried out to study ion-exchange properties of the material. Distribution studies for various metal ions revealed that the nano composite is highly selective for Cd(II). An ion-selective membrane electrode was fabricated using this material for the determination of Cd(II) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.

  11. Kinetics, thermodynamics and surface heterogeneity assessment of uranium(VI) adsorption onto cation exchange resin derived from a lignocellulosic residue

    International Nuclear Information System (INIS)

    A new cation exchange resin (PGTFS-COOH) having a carboxylate functional group at the chain end was prepared by grafting poly(hydroxyethylmethacrylate) onto tamarind fruit shell, TFS (a lignocellulosic residue) using potassium peroxydisulphate-sodium thiosulphate redox initiator, and in the presence of N,N'-methylenebisacrylamide (MBA) as a crosslinking agent, followed by functionalisation. The adsorbent was characterized with the help of FTIR, XRD, scanning electron micrographs (SEM), and potentiometric titrations. The kinetic and isotherm data, obtained at optimum pH value 6.0 at different temperatures could be fitted with pseudo-second-order equation and Sips isotherm model, respectively. An increase in temperature induces positive effect on the adsorption process. The calculated activation energy of adsorption (Ea, 18.67 kJ/mol) indicates that U(VI) adsorption was largely due to diffusion-controlled process. The values of adsorption enthalpy, Gibbs free energy, and entropy were calculated using thermodynamic function relationships. The decrease in adsorption enthalpy with increasing U(VI) uploading on the adsorbent, reflects the surface energetic heterogeneity of the adsorbent. The isosteric heat of adsorption was quantitatively correlated with the fractional loading for the U(VI) ions adsorption onto PGTFS-COOH. The results showed that the PGTFS-COOH possessed heterogeneous surface with sorption sites having different activities.

  12. Cation exchange capacity (Qv) estimation in shaly sand reservoirs: case studies in the Junggar Basin, northwest China

    Science.gov (United States)

    Wang, Liang; Mao, Zhi-Qiang; Sun, Zhong-Chun; Luo, Xing-Ping; Deng, Ren-Shuang; Zhang, Ya-Hui; Ren, Bing

    2015-10-01

    Cation exchange capacity (Qv) is a key parameter in resistivity-based water saturation models of shaly sand reservoirs, and the accuracy of Qv calculation is crucial to the prediction of saturations of oil and gas. In this study, a theoretical expression of Qv in terms of shaly sand permeability (Kshaly-sand), total porosity (ϕt), and salinity of formation water (S) is deduced based on the capillary tube model and the physics volume model. Meanwhile, the classical Schlumberger-Doll research (SDR) model has been introduced to estimate Kshaly-sand. On this basis, a novel technique to estimate Qv from nuclear magnetic resonance (NMR) logs is proposed, and the corresponding model is also established, whose model parameters are calibrated by laboratory Qv and NMR measurements of 15 core samples from the Toutunhe formation of the Junggar Basin, northwest China. Based on the experimental data sets, this technique can be extended to reservoir conditions to estimate continuous Qv along the intervals. The processing results of field examples illustrate that the Qv calculated from field NMR logs are consistent with the analyzed results, with the absolute errors within the scope of  ±0.1 mmol cm-3 for the majority of core samples.

  13. Enhanced photocatalytic activity of chromium(VI) reduction and EDTA oxidization by photoelectrocatalysis combining cationic exchange membrane processes.

    Science.gov (United States)

    Hsu, Hung-Te; Chen, Shiao-Shing; Tang, Yi-Fang; Hsi, Hsing-Cheng

    2013-03-15

    A novel technology of photoelectrocatalysis (PEC) combining with cationic exchange membrane (CEM) was proposed for simultaneous reduction of chromium(VI) and oxidization of EDTA. The application of CEM was used to enhance the efficiency for prevention of the re-oxidation of reduced chromium with the electron-hole pairs. In this study, effects of current density, pH, TiO2 dosage, hydraulic retention time (HRT), light intensity and EDTA/Cr(VI) molar ratio were all investigated. The results showed that the optimum conversion efficiency occurred at 4mA/cm(2) with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged TiOH2(+), and negatively charged Cr(VI) and EDTA. The optimum TiO2 loading of 1g/L was depended mainly on the acidic pH range, especially at higher HRT and irradiation intensity. In addition, higher EDTA/Cr(VI) molar ratio enhanced the reduction efficiency of Cr(VI), indicating EDTA plays the role of hole scavenger in this system. Moreover, incomplete EDTA decomposition contributes to the occurrence of intermediates, including nitrilotriacetic acid, iminodiacetic acid, glycine, oxamic acid, lyoxylic acid, oxalic acid, acetic acid and formic acid, as identified by GC/MS. Consequently, transformation pathway was determined from these analyzed byproducts and molecular orbital package analysis. PMID:23380448

  14. On separation of exchange term from the coefficient of the magnetoelectromechanical coupling

    Indian Academy of Sciences (India)

    ZAKHARENKO A A

    2016-06-01

    The purpose of this analysis is to introduce the separated exchange coefficient and to graphically investigate it. This coefficient, depending on the electromagnetic constant plus two coefficients of the electromechanical and magnetomechanical couplings, form the coefficient of magnetoelectromechanical coupling (CMEMC), a very important characteristic used for analysingmagnetoelectroelastic smart (composite) materials. It was analytically and graphically demonstrated that the CMEMC can have a minimum due to the minimum of the exchange coefficient at a certain value of the electromagnetic constant. For graphical investigation, the frequently used transverselyisotropic (6$mm$) composite materials such as BaTiO$_3$–CoFe$_2$O$_4$ and PZT–5H–Terfenol–D are exploited.

  15. Intensification of heat and mass transfer by ultrasound: application to heat exchangers and membrane separation processes.

    Science.gov (United States)

    Gondrexon, N; Cheze, L; Jin, Y; Legay, M; Tissot, Q; Hengl, N; Baup, S; Boldo, P; Pignon, F; Talansier, E

    2015-07-01

    This paper aims to illustrate the interest of ultrasound technology as an efficient technique for both heat and mass transfer intensification. It is demonstrated that the use of ultrasound results in an increase of heat exchanger performances and in a possible fouling monitoring in heat exchangers. Mass transfer intensification was observed in the case of cross-flow ultrafiltration. It is shown that the enhancement of the membrane separation process strongly depends on the physico-chemical properties of the filtered suspensions. PMID:25216897

  16. Phase separation and exchange bias effect in Ca doped EuCrO3

    International Nuclear Information System (INIS)

    The rare-earth chromites have attracted increasing interests in recent years, as a member of a few single-phase multiferroic materials. We studied the structure and magnetic property of a series of Ca-doped EuCrO3 samples by using X-ray powder diffraction and Physical Property Measurement System. Phase separation, rotation of magnetization in M(T) curve and exchange bias effect have been identified. The Eu0.7Ca0.3CrO3 polycrystalline sample may be intrinsically phase-separated, with Cr3+-rich, Cr4+-rich canted antiferromagnetic regions surrounded by spin glass-like frustrated phase, resulting in several magnetic features including: (1) a broad and slow increase of M(T) curve with the decrease of temperature; (2) rotation of magnetization with increasing cooling field; (3) exchange bias and glassy magnetism. The rotation of magnetization is ascribed to the rotation of the moment of Cr4+-rich regions, arising from the competition between exchange coupling energy and magnetostatic energy. The exchange bias effect suggests the formation of weak ferromagnetic unidirectional anisotropy during field cooling, due to the exchange coupling among weak ferromagnetic domains and surrounding spin glass-like regions. This result helps understanding the interaction among different magnetic domains and phases in a complex system. - Highlights: • Exchange bias effect and glassy magnetism were observed in Eu0.7Ca0.3CrO3. • Rotation of the moments of Cr4+-rich regions result in the rotation of magnetization in M(T) curve. • Spin glass-like regions contribute to the observed exchange bias effect

  17. Phase separation and exchange bias effect in Ca doped EuCrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Dongmei, E-mail: dmdeng@shu.edu.cn [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Wang, Xingyu; Zheng, Jiashun; Qian, Xiaolong [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Yu, Dehong; Sun, Dehui [Bragg Institute, Australian Nuclear Science and Technology Organization, Kirrawee DC, NSW 2232 (Australia); Jing, Chao [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Lu, Bo [Analysis and Measurement Center and Laboratory for Microstructures of Shanghai University, Shanghai 200444 (China); Kang, Baojuan; Cao, Shixun; Zhang, Jincang [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China)

    2015-12-01

    The rare-earth chromites have attracted increasing interests in recent years, as a member of a few single-phase multiferroic materials. We studied the structure and magnetic property of a series of Ca-doped EuCrO{sub 3} samples by using X-ray powder diffraction and Physical Property Measurement System. Phase separation, rotation of magnetization in M(T) curve and exchange bias effect have been identified. The Eu{sub 0.7}Ca{sub 0.3}CrO{sub 3} polycrystalline sample may be intrinsically phase-separated, with Cr{sup 3+}-rich, Cr{sup 4+}-rich canted antiferromagnetic regions surrounded by spin glass-like frustrated phase, resulting in several magnetic features including: (1) a broad and slow increase of M(T) curve with the decrease of temperature; (2) rotation of magnetization with increasing cooling field; (3) exchange bias and glassy magnetism. The rotation of magnetization is ascribed to the rotation of the moment of Cr{sup 4+}-rich regions, arising from the competition between exchange coupling energy and magnetostatic energy. The exchange bias effect suggests the formation of weak ferromagnetic unidirectional anisotropy during field cooling, due to the exchange coupling among weak ferromagnetic domains and surrounding spin glass-like regions. This result helps understanding the interaction among different magnetic domains and phases in a complex system. - Highlights: • Exchange bias effect and glassy magnetism were observed in Eu{sub 0.7}Ca{sub 0.3}CrO{sub 3}. • Rotation of the moments of Cr{sup 4+}-rich regions result in the rotation of magnetization in M(T) curve. • Spin glass-like regions contribute to the observed exchange bias effect.

  18. Direct separation of 67Ga citrate from zinc and copper target materials by an ion exchange

    International Nuclear Information System (INIS)

    The separation of 67Ga from zinc and copper target materials using an anion- f:exchanger (Dowex21K) and 0.1 M citrate buffer at pH 6 is described. The gallium-67 was separated in citrate solution and can be directly used for medical applications. Gallium-67 with a half-life of 78.3 h and gamma-rays with energies of 93, 185 and 300 keV is a cyclotron produced radioisotope for which a considerable demand exists. 67Ga is frequently produced through proton or deuteron bombardment of natural or enriched Zn targets (Helus and Maier-Borst, 1973). It is usually separated from Zn by ion exchange chromatography (Helus and Maier-Borst, 1973; van der Walt and Strelow, 1983) or by liquid extraction Helus and Maier-Borst, 1973; Hupf and Beaver, 1970). The isotope is usually supplied in citrate solution which is widely used as 67Ga Gallium citrate which is a well-established radiopharmaceutical for imaging soft tissue tumors and abscesses. Several routes for large scale production of 67Ga and the development of medical applications have been reported (Silvester and Thakur, 1970; Dahl and Tilbury, 1972; Steyn and Meyer,1973; Vlatkovic et al., 1975; Neirinckx, 1976; Thakur, 1977). Various attempts were carried out to separate gallium-67 by using different ion exchange methods (Strelow et al., 1971; Das and Ramamoorthy, 1995; Boothe et al.,1991) through the labelling of citrate by using 67Ga was carried out for medical applications

  19. The partitioning of sulfur and chlorine between andesite melts and magmatic volatiles and the exchange coefficients of major cations

    Science.gov (United States)

    Zajacz, Zoltán; Candela, Philip A.; Piccoli, Philip M.; Sanchez-Valle, Carmen

    2012-07-01

    Andesite melts were equilibrated with an H-O-S-bearing volatile phase to determine the partition coefficients for S and Cl as a function of melt composition and oxygen fugacity. The experiments were conducted in rapid-quench MHC vessel assemblies at 200 MPa and 1000 °C, and over a range of imposed fO2 between NNO-1.2 and NNO+1.8. High fluid/melt mass ratios (∼15) were employed, allowing precise and accurate partition coefficients to be obtained by mass balance calculations. Chlorine exhibits Henrian behavior at ClO-0.5 activities typical for arc magmas, with D Cl volatile/melt = 1.36 ± 0.06 (1σ) below 0.2 wt.% Cl in the melt; at higher ClO-0.5 activities, D Cl volatile/melt increases linearly to 2.11 ± 0.02 at 1 wt.% Cl in the melt. In the volatile phase: FeCl2 ∼ NaCl > KCl ∼ HCl. The determination of cation exchange coefficients for major cations yielded: K K,Na volatile/melt = 1.23 ± 0.10 (1σ) and ∗K Fe,Na volatile/melt = D Fe volatile/melt / D Na volatile/melt = 1.08 ± 0.16 (1σ). Under these conditions, the concentration of HCl in the vapor is negatively correlated with the (Na + K)/(Al + Fe3+) ratio in the melt. Reduced sulfur (S2-) appears to obey Henry's law in andesite melt-volatile system at fH2S below pyrrhotite saturation. The partition coefficient for S at fO2 = NNO-0.5 correlates negatively with the FeO concentration in the melt, changing from 254 ± 25 at 4.0 wt.% FeO to 88 ± 6 at 7.5 wt.% FeO. Pyrrhotite saturation is reached when approximately 3.2 mol% S is present in the volatile phase at fO2 = NNO-0.5. At the sulfide/sulfate transition, the partition coefficient of S drops from 171 ± 23 to 21 ± 1 at a constant FeO content of ∼6 wt.% in the melt. At fO2 = NNO+1.8, anhydrite saturation is reached at ∼3.3 mol% S present in the volatile phase. Aqueous volatiles exsolving from intermediate to mafic magmas can efficiently extract S, and effect its transfer to sites of magmatic-hydrothermal ore deposit formation.

  20. Separation of metal ions by anion exchange in mixtures of hydrochloric acid and hydrofluoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Faris, J.P.

    1978-12-01

    Distribution coefficients were determined for the adsorption of more than 40 elements on anion-exchange resins from mixtures of HCl (0.1 to 12M) and HF (0.1-8M). Two resins, Dowex 1 x 10, 200 to 400 mesh and Dowex 1 x 4, 100 to 200 mesh, were used. Distribution coefficients were also determined for the adsorption of many elements on both resins from 0.1 to 12M HCl and 0.1 to 12M HF. Anion exchange in the presence of HF was found useful for separating impurities from various materials for their subsequent determination, and specific procedures used in our spectrochemical laboratory for this purpose are outlined. The results of a literature search on the use of anion exchange in hydrofluoric acid and fluoride-containing media are presented in an extensive bibliography. 404 references, 9 tables.

  1. A study of an ion-exchange process for separation of strontium and yttrium

    International Nuclear Information System (INIS)

    A study has been carried out to determine optimum conditions for the separation of strontium and yttrium by ion-exchange. The parameters of interest for such separation such as the dimensions of the ion-exchange columns, flow rates through the columns and pH values of the solutions, which affect the overall yield in the process, have been investigated. Application of this method for routine quantitative determinations of Sr-90 in environmental samples, particularly the wet-ashed biological materials has also been studied. The method, although a rapid and convenient one has not been found to yield consistent results probably due to the requirement of stringent analytical controls during the process. (author)

  2. Application of mixed-mode, solid-phase extraction in environmental and clinical chemistry. Combining hydrogen-bonding, cation-exchange and Van der Waals interactions

    Science.gov (United States)

    Mills, M.S.; Thurman, E.M.; Pedersen, M.J.

    1993-01-01

    Silica- and styrene-divinylbenzene-based mixed-mode resins that contain C8, C18 and sulphonated cation-exchange groups were compared for their efficiency in isolation of neutral triazine compounds from water and of the basic drug, benzoylecgonine, from urine. The triazine compounds were isolated by a combination of Van der Waals and hydrogen-bonding interactions, and benzoylecgonine was isolated by Van der Waals interactions and cation exchange. All analytes were eluted with a polar organic solvent contaning 2% ammonium hydroxide. Larger recoveries (95%) were achieved on copolymerized mixed-mode resins where C18 and sulfonic acid are in closer proximity than on 'blended' mixed-mode resins (60-70% recovery).

  3. Effects of Land Use Practices on the Organic Carbon Content, Cation Exchange Capacity and Aggregate Stability of Soils in the Catchment Zones

    OpenAIRE

    Mosayeb Heshmati; Arifin Abdu; Shamshuddin Jusop; Nik M. Majid

    2011-01-01

    Problem statement: Land use practice leads to changes in the physico-chemical properties of soils, such as Soil Organic Carbon (SOC), Cation Exchange Capacity (CEC) and Soil Aggregate Stability (SAS) that cause soil erosion. Approach: Merek catchment, Iran suffers from land degradation due to poor land use practice. A study was carried out with the objectives: (i) to determine soil nutrient status in different agro-ecological zones in Merek catchment; and (ii) to evaluate the influence of lan...

  4. 离子色谱分离法提纯异麦芽低聚糖%Purification of isomalto-oligosaccharide by cation exchange chromatography

    Institute of Scientific and Technical Information of China (English)

    姜守霞; 励雯波; 钟振声

    2003-01-01

    The purification of isomalto-oligsaccharide syrup using cation exchange resin was smdiied. The experiments showed that, when 35 ml raw material was used, the optimal purification result could be achieved on the resin column of 9 × 4000 mm with eluting rate 9 ml/min at 71℃ .The content of gluecose could be decreased whist the content of active components would be relatively increased.The purity of isomalto-oligsaccharide could be further increased by re-purification.

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

    International Nuclear Information System (INIS)

    137Cs (t1/2 = 30 years) is one of the major radioisotope present in high level liquid waste (HLLW) generated during the reprocessing of nuclear fuel. Separation of 137Cs from HLLW results in reduction of personal radiation exposure during the conditioning, transportation, storage and disposal. In addition, 137Cs 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

  6. studies on the use of organic and inorganic ion exchangers for separation of indium(III) from cadmium(II) using analytical methods

    International Nuclear Information System (INIS)

    Organic and inorganic ion exchangers have many applications not only in the industrial, environmental and the nuclear fields but also in the separation of metal ions. This may be returned to its high measured capacity, high selectivity for some metal ions, low solubility, high chemical radiation stability and easy to use.Indium and cadmium are produced from cyclotron target where the solvent extraction represents an ordinary method for separation of indium and cadmium from its target. In the present work, More than chromatographic columns were successfully used for the separation and recovery of indium(III) and cadmium(II) ions from di-component system in aqueous solution using organic and inorganic ion exchangers. The work was carried out in three main parts;1- In the first part, the commercial resin (Dowex50w-x8) was used for the separation of indium from cadmium. The effect of pH, the weight of resin, and equilibrium time on the sorption process of both metal ions were determined. It was found that the adsorption percentage was more than 99% at pH 4 (as optimum pH value) using batch experiment. The results show that indium was first extracted while cadmium is slightly extracted at this pH value. The recovery of indium and cadmium is about 98% using hydrochloric acid as best eluent. The ion exchange/complexing properties of Dowex50w-x8 resin containing various substituted groups towards indium and cadmium cations were investigated.2- In the second part, Zn(II)polymethacrylates, and poly (acrylamide-acrylic acid), as synthetic organic ion exchangers were prepared by gamma irradiation polymerization technique of the corresponding monomer at 30 kGy. The obtained organic resins were mixed with indium ions to determine its capacity in aqueous solutions using batch experiment.

  7. Controllable conversion of plasmonic Cu2-xS nanoparticles to Au2S by cation exchange and electron beam induced transformation of Cu2-xS-Au2S core/shell nanostructures.

    Science.gov (United States)

    Wang, Xianliang; Liu, Xin; Zhu, Dewei; Swihart, Mark T

    2014-08-01

    Self-doped Cu2-xS nanocrystals (NCs) were converted into monodisperse Cu2-xS-Au2S NCs of tunable composition, including pure Au2S, by cation exchange. The near-infrared (NIR) localized surface plasmon resonance (LSPR) was dampened and red-shifted with increasing Au content. Cation exchange was accompanied by elimination of cation vacancies and a change in crystal structure. Partially exchanged Cu2-xS-Au2S core/shell structures evolved to dumbbell-like structures under electron irradiation in the transmission electron microscope (TEM).

  8. Effect of the intercalated cation-exchanged on the properties of nanocomposites prepared by 2-aminobenzene sulfonic acid with aniline and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Toumi, I. [Laboratoire de Chimie Organique, Macromoleculaire et des Materiaux, Universite de Mascara, Bp 763 Mascara 29000 (Algeria); Benyoucef, A., E-mail: ghani29000@yahoo.fr [Laboratoire de Chimie Organique, Macromoleculaire et des Materiaux, Universite de Mascara, Bp 763 Mascara 29000 (Algeria); Yahiaoui, A. [Laboratoire de Chimie Organique, Macromoleculaire et des Materiaux, Universite de Mascara, Bp 763 Mascara 29000 (Algeria); Quijada, C. [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Pza Ferrandiz i Carbonel, E-03801 Alcoy, Alicante (Spain); Morallon, E. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)

    2013-02-25

    Polymer/montmorillonite nanocomposites were prepared. Intercalation of 2-aminobenzene sulfonic acid with aniline monomers into montmorillonite modified by cation was followed by subsequent oxidative polymerization of monomers in the interlayer spacing. The clay was prepared by cation exchange process between sodium cation in (M-Na) and copper cation (M-Cu). XRD analyses show the manifestation of a basal spacing (d-spacing) for M-Cu changes depending on the inorganic cation and the polymer intercalated in the M-Cu structure. TGA analyses reveal that polymer/M-Cu composites is less stable than M-Cu. The conductivity of the composites is found to be 10{sup 3} times higher than that for M-Cu. The microscopic examinations including TEM picture of the nanocomposite demonstrated an entirely different and more compatible morphology. Remarkable differences in the properties of the polymers have also been observed by UV-Vis and FTIR, suggesting that the polymer produced with presence of aniline has a higher degree of branching. The electrochemical behavior of the polymers extracted from the nanocomposites has been studied by cyclic voltammetry which indicates the electroactive effect of nanocomposite gradually increased with aniline in the polymer chain.

  9. Estimation of soil cation exchange capacity using Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS)

    Science.gov (United States)

    Emamgolizadeh, S.; Bateni, S. M.; Shahsavani, D.; Ashrafi, T.; Ghorbani, H.

    2015-10-01

    The soil cation exchange capacity (CEC) is one of the main soil chemical properties, which is required in various fields such as environmental and agricultural engineering as well as soil science. In situ measurement of CEC is time consuming and costly. Hence, numerous studies have used traditional regression-based techniques to estimate CEC from more easily measurable soil parameters (e.g., soil texture, organic matter (OM), and pH). However, these models may not be able to adequately capture the complex and highly nonlinear relationship between CEC and its influential soil variables. In this study, Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS) were employed to estimate CEC from more readily measurable soil physical and chemical variables (e.g., OM, clay, and pH) by developing functional relations. The GEP- and MARS-based functional relations were tested at two field sites in Iran. Results showed that GEP and MARS can provide reliable estimates of CEC. Also, it was found that the MARS model (with root-mean-square-error (RMSE) of 0.318 Cmol+ kg-1 and correlation coefficient (R2) of 0.864) generated slightly better results than the GEP model (with RMSE of 0.270 Cmol+ kg-1 and R2 of 0.807). The performance of GEP and MARS models was compared with two existing approaches, namely artificial neural network (ANN) and multiple linear regression (MLR). The comparison indicated that MARS and GEP outperformed the MLP model, but they did not perform as good as ANN. Finally, a sensitivity analysis was conducted to determine the most and the least influential variables affecting CEC. It was found that OM and pH have the most and least significant effect on CEC, respectively.

  10. Experimental Findings On Minor Actinide And Lanthanide Separations Using Ion Exchange

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-17

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

  11. Proceedings of the efficient separations and processing crosscutting program 1997 technical exchange meeting

    International Nuclear Information System (INIS)

    This document contains summaries of technology development presented at the 1997 Efficient Separations and Processing Crosscutting Program (ESP-CP) Technical Exchange Meeting (TEM), held January 28-30, 1997, in Gaithersburg, Maryland. The ESP-CP is sponsored by the U.S. Department of Energy's Office of Environmental Management (DOE/EM), Office of Science and Technology. The ESP-CP TEM is held annually to: (1) Present current technology development activities funded by the ESP-CP. Developers of ESP-CP-funded technologies describe the problems and needs addressed by their technologies; the technical approach, accomplishments, and resolution of issues; the strategy and schedule for commercialization; and evolving potential applications. Representatives from DOE/EM's Focus Areas also present their technology needs. (2) Promote the exchange of technical information among those developing new separations technologies, those responsible for providing new separations technologies to meet DOE/EM needs, and those who need or will potentially make use of such technologies. (3) Familiarize the ESP-CP Technical Review Team with the FY 1997 program and solicit reviewers' views on the program as a whole. This meeting is not a program review of the individual tasks, but instead focuses on the technical aspects and implementation of ESP-CP-sponsored technology or data. This document also contains a list of ESP-CP-sponsored publications, presentations, and patents. Separate abstracts have been indexed into the energy database for contributions to this proceedings

  12. New Anion-Exchange Resins for Improved Separations of Nuclear Materials

    International Nuclear Information System (INIS)

    Improved separations of nuclear materials will have a significant impact upon a broad range of DOE activities. DOE-EM Focus Areas and Crosscutting Programs have identified improved methods for the extraction and recovery of radioactive metal ions from process, waste, and environmental waters as critical needs for the coming years. We propose to develop multifunctional anion-exchange resins that facilitate anion uptake by carefully controlling the structure of the anion receptor site. Our new ion-exchange resins interface the field of ion-specific chelating ligands with robust, commercial ion-exchange technology to provide materials which exhibit superior selectivity and kinetics of sorption and desorption. The following Focus Areas and Crosscutting Programs have described needs that would be favorably impacted by the new material: Efficient Separations and Processing - radionuclide removal from aqueous phases; Plutonium - Pu, Am or total alpha removal to meet regulatory requirement s before discharge to the environment; Plumes - U and Tc in groundwater, U, Pu, Am, and Tc in soils; Mixed Waste - radionuclide partitioning; High-Level Tank Waste - actinide and Tc removal from supernatants and/or sludges. The basic scientific issues which need to be addressed are actinide complex speciation along with modeling of metal complex/functional site interactions in order to determine optimal binding-site characteristics. Synthesis of multifunctionalized extractants and ion-exchange materials that implement key features of the optimized binding site, and testing of these materials, will provide feedback to the modeling and design activities. Resin materials which actively facilitate the uptake of actinide complexes from solution should display both improved selectivity and kinetic properties. The long-range implications of this research, however, go far beyond the nuclear complex. This new methodology of ''facilitated uptake'' could revolutionize ion-exchange technology

  13. The selective separation of Cs and Sr ion on the inorganic ion-exchanger zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hun Hwee; Min, Byeog Heon [Hoseo University, Taegu (Korea)

    1998-04-01

    This study shows the selective separation of Cs and Sr ion on the inorganic ion-exchanger zeolites such as clinoptilolite, Y-type CBV760, CBV780 and A-type 3A. The selective separation of Cs and Sr on these zeolites was examined using batch and continuous column experiments. For the selective separation of Cs and Sr from a synthetic wastewater, adsorption rate of Cs increased in the order, clinoptilolite> 3A>> CBV760> CBV780, adsorption rate of Sr increased in the other, 3A>> clinoptilolite> CBV760> CBV780. For the clinoptilolite, the adsorption rate of Cs reached about 96 {approx} 98% within 3h. The adsorption rate of Sr on 3A reached about 99% within 3h. (author). 40 refs., 27 figs., 4 tabs.

  14. Cation exchange synthesis of uniform PbSe/PbS core/shell tetra-pods and their use as near-infrared photodetectors

    Science.gov (United States)

    Mishra, N.; Mukherjee, B.; Xing, G.; Chakrabortty, S.; Guchhait, A.; Lim, J. Y.

    2016-07-01

    In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as `templates'. We also fabricated near-infrared (NIR) photodetectors with a very simple architecture comprising a PbSe/PbS tetrapod layer between two Au electrodes on a glass substrate. When illuminated by a NIR laser, these devices are capable of achieving a responsivity of 11.9 A W-1 without the use of ligand-exchange processes, thermal annealing or hybrid device architecture. Transient absorption spectroscopy was carried out on these PbSe/PbS tetrapods, the results of which suggest that the branched morphology contributes in part to device performance. Investigation of the charge dynamics of the PbSe/PbS tetrapods revealed an extremely long-lived exciton recombination lifetime of ~17 ms, which can result in enhanced photoconductive gain. Overall, these heterostructured tetrapods showcase simultaneously the importance of nanoparticle shape, band structure, and surface chemistry in the attainment of NIR photodetection.In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as `templates'. We also fabricated near-infrared (NIR) photodetectors

  15. Effects of Polar Organic Solvent on Separation of Y(edta)-/Nd(edta)- Complexes on Polyacrylic Anion Exchangers

    Institute of Scientific and Technical Information of China (English)

    Halina Hubicka; Dorota Kolodynska

    2005-01-01

    The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exchangers, particularly the weakly basic, gel anion exchanger Amberlite IRA 68, can be applied to the separation of rare earth complexes with EDTA in H2O-methanol and H2O-ethanol systems. In most cases the determined distribution coefficients of Ln3+ complexes with EDTA in mixed media like water-methanol on polyacrylate anion exchangers are larger than those in pure water media.

  16. RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Fox, E

    2009-05-15

    Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals.

  17. Separation and determination of alditols and sugars by high-pH anion-exchange chromatography with pulsed amperometric detection

    DEFF Research Database (Denmark)

    Andersen, Rikke; Sørensen, A.

    2000-01-01

    Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic...

  18. Influência da matéria orgânica na capacidade de troca de cations do solo Cation-exchange capacity of the organic fraction of soils

    Directory of Open Access Journals (Sweden)

    F. da Costa Verdade

    1956-01-01

    . The cation-exchange capacity and other data on these soils show that the organic fraction must play an important role in the cation-exchange process. The study of the adsorptive capacity of the organic matter was done by destruction of the organic fraction of the soil by 12% hydrogen peroxide. For heavy textured soils the results show that the organic fraction most resistant to oxidation had a higher cation-exchange capacity than the portion first oxidized. For sandy soils all organic fractions had the same magnitude in the base adsorbing power. It was observed that the organic matter seems to inhibit the base-exchange capacity of the mineral fraction. Plotting the percentage of cation-exchange capacity of the organic fraction against the percentage of organic carbon in the soil, a curve is determined which shows the inhibition phenomenon. The results were rather scattered and the experiments are now being repeated to elucidate these observations. The organic cation-exchange capacity of soils in São Paulo is 30-40% for fine textured soils and 50-60% for sandy soils. Since most of the farming land in São Paulo belongs to the sandy soil group called Bauru, the problem of maintaining or increasing the fertility of these soils is dependent on their organic matter content.

  19. Efficient Separation of Lanthanides Using Poly (Styrene-Divinyl Benzene) Aminated Anion Exchanger

    International Nuclear Information System (INIS)

    New chromatographic method was developed for the determination and separation of lanthanides using AS4A anionic column. The behavior of the column towards lanthanides was studied through many parameters, From the data obtained it is found that, affinity of the column toward investigated ions increase by increasing eluent concentration and it decrease retention factors. With the two investigated eluent (oxalic and citric acids), elution order for lanthanide elements was obtained in their atomic number from La to Lu. Retention times and retention orders obtained at these conditions clearly show that, lanthanides in AS4A are displaced according to anion exchange mechanism. More over separation of lanthanides using AS4A was studied using isocratic and gradient elution programs. Light and the first intermediate lanthanide elements were separated successfully by applying a gradient program containing 70% oxalic acid (100 mM) and 30% water. The problem of separation for heavy and the last intermediate lanthanide elements was solved using 100 mM alpha hydroxy isobutyric acid (α-HIBA)

  20. Obtention of the cation exchange capacity of a natural kaolinite with radioactive tracers; Obtencion de la capacidad de intercambio cationico de una kaolinita natural con trazadores radioactivos

    Energy Technology Data Exchange (ETDEWEB)

    Uribe I, A.; Badillo A, V.E. [Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Monroy G, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: Adrya81@hotmail.com

    2005-07-01

    One of the more used techniques for the elimination of the heavy metals present in water systems is to use adsorbent mineral phases like zeolites and clays, among others. The clays are able to exchange easily the fixed ions in the external surface of its crystals or well the ions present in the interlaminar spaces of the structures, for other existent ones in the encircling aqueous solutions for that the Cation exchange capacity (CIC) is defined as the sum of all the cations exchange that a mineral can possess independent to the physicochemical conditions. The CIC is equal to the measure of the total of negative charges of the mineral by mass of the solid (meq/g). In this investigation work, the value of the CIC equal to 2.5 meq/100 g is obtained, of a natural kaolinite from the State of Hidalgo studying the retention of the sodium in the kaolinite with the aid of the radioactive isotope {sup 24} Na and of the selective electrodes technique, making vary the pH value. So is experimentally demonstrated that the CIC is an intrinsic property of the mineral independent of the pH value of the solution and of the charges origin. (Author)

  1. Properties of solvated electrons, alkali anions and other species in metal solutions and kinetics of cation and electron exchange reactions. Final report

    International Nuclear Information System (INIS)

    The properties of solutions of alkali metals in amine solvents were studied by optical, ETR, NMR and electrochemical methods. Complexation of the alkali cations by crown ethers and cryptands permitted the preparation of concentrated solutions of alkali metals in amine and ether solvents. Extensive alkali metal NMR studies of the exchange of M+ with crown-ethers and cryptands and of the alkali metal anion, M-, were made. The first crystalline salt of an alkali metal anion, Na+ Cryptand [2.2.2]Na- was synthesized and characterized and led to the preparation of other alkali metal anion salts. This research provided the foundation for continuing studies of crystalline alkalide salts

  2. A comparative account of the wet oxidation of cation exchange resin with hydrogen peroxide using titanium, vanadium, and molybdenum doped MCM-41 as catalysts

    International Nuclear Information System (INIS)

    Ion exchange resins are widely used in the nuclear industry for treatment of radioactive waste as well as for the upgrading of heavy water used in the primary heat transport system and moderator system. Repeated usage of the resins calls for replacement and treatment before disposal. The present work involves the application of metal-doped MCM-41 material as a catalyst for the wet oxidation of cation exchange resins using hydrogen peroxide as an oxidizing agent. The sulfate produced from the exchangeable group of the resin reflects the extent of decomposition and the carbonate produced reflects the extent of oxidation of the ion exchange resin. Results indicate that the percentage decomposition and oxidation increase with the weight of the catalyst and the volume of the oxidant, i.e., hydrogen peroxide. As much as 0.5 g of the resin could be decomposed by 12 mL of 30% hydrogen peroxide to 98.7% and oxidized to 99.25% using molybdenum doped MCM-41. Vanadium doped and titanium doped MCM-41 required 14 to 16 mL for complete decomposition and 18 to 20 mL for complete oxidation of the ion exchange resin. (orig.)

  3. Adsorption separation of carbon dioxide, methane, and nitrogen on Hβ and Na-exchanged β-zeolite

    Institute of Scientific and Technical Information of China (English)

    Xiaoliang Xu; Xingxiang Zhao; Linbing Sun; Xiaoqin Liu

    2008-01-01

    Adsorption isotherms of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on Hβ and sodium exchanged β-zeolite (Naβ) were volumetrically measured at 273 and 303 K. The results show that all isotherms were of Brunauer type Ⅰ and well correlated with Langmuir-Freundlich model. After sodium ions exchange, the adsorption amounts of three adsorbates increased, while the increase magnitude of CO2 adsorption capacity was much higher than that of CH4 and N2. The selectivities of CO2 over CH4 and CO2 over N2 enhanced after sodium exchange. Also, the initial heat of adsorption data implied a stronger interaction of CO2 molecules with Na+ ions in Naβ. These results can be attributed to the larger electrostatic interaction of CO2 with extraframework cations in zeolites. However, Naβ showed a decrease in the selectivity of CH4 over N2, which can be ascribed to the moderate affinity of N2 with Naβ. The variation of isosteric heats of adsorption as a function of loading indicates that the adsorption of CO2 in Naβ presents an energetically heterogeneous profile. On the contrary, the adsorption of CH4 was found to be essentially homogeneous, which suggests the dispersion interaction between CH4 and lattice oxygen atoms, and such interaction does not depend on the exchangeable cations of zeolite.

  4. Separation of phenolic acids from natural plant extracts using molecularly imprinted anion-exchange polymer confined ionic liquids.

    Science.gov (United States)

    Bi, Wentao; Tian, Minglei; Row, Kyung Ho

    2012-04-01

    Polymer-confined ionic liquids were used for the separation of phenolic acids from natural plant extract by utilizing an anion-exchange mechanism. They were synthesized using molecular imprinting technique to reduce non-directional ion-ion interactions during anion-exchange and other interactions with interference substances that could decrease selectivity. A suitable sorbent for phenolic acid separation could be identified based on the adsorption behaviors of phenolic acids on different polymer-confined ionic liquids. Thus, the developed ionic liquid-based molecularly imprinted anion-exchange polymer (IMAP) achieved high recovery rates by solid-phase extraction of phenolic acids from Salicornia herbacea L. extract: 90.1% for protocatechuic acid, 95.5% for ferulic acid and 96.6% for caffeic acid. Moreover, the phenolic acids were separable from each other by repeated solid phase extraction cycles. The proposed method could be used to separate other phenolic acids or organic acids from complex samples. PMID:21903215

  5. Conception and estimation of new zirconium/hafnium separation process: nano-filtration-complexation, solvent extraction and ions-exchangers

    International Nuclear Information System (INIS)

    High purity zirconium is used as fuel cladding material in nuclear power plant. Zirconium does not absorb much neutrons, contrary to hafnium. These elements coexist in nature (3% hafnium in zircon). So they must be separated. This Ph.D. deal with the separation of zirconium from hafnium by using different techniques. In nano-filtration-complexation, zirconium/hafnium nitrates mixture is separated by using amino-carboxylate ligands through nano-filtration membranes. In solvent extraction, zirconium is extracted in high hydrochloric acid concentration media. Zirconium/hafnium separation is studied by using ion-exchangers resins in batch-wise and elution from ion-exchangers resins. Liquid-liquid and solid-liquid Systems characterization is carried out with the aim of modelling. Free hafnium zirconium and free zirconium hafnium are obtained by solvent extraction and ion exchangers. (author)

  6. Materials for Electroactive Ion-Exchange (EaIX) Separations of Pertechnetate Ion

    Energy Technology Data Exchange (ETDEWEB)

    Stender, Matthias; Hubler, Timothy L.; Alhoshan, Mansour; Smyrl, William H.

    2004-03-29

    Many contaminants of interest to the U.S. Department of Energy (DOE) exist as anions (e.g. chromate, pertechnetate and nitrate). The objective of this study is to develop Electroactive Ion-Exchange (EaIX) materials. Such materials can be used to separate pertechnetate ion from radioactive wastes located at DOE sites while limiting the amount of secondary wastes generated. We have developed a synthetic strategy to prepare vinyl-bipyridyl and -terpyridyl ligands which allow incorporation of ion-selective architectures with a polymerizable handle. Fe complexes formed with these ligands provide the working core of the electroactive polymers. The polymers can be directly used as materials for EaIX or they can be incorporated into porous composite materials that are then used for EaIX.

  7. Catalytic spectrophotometric determination of cerium by ion exchange separation coupled to a flow injection system

    International Nuclear Information System (INIS)

    A flow injection method is described intended for the determination of cerium based on its catalytic effect on the oxidation of gallocyanine by peroxydisulfate in acidic media. The proposed flow injection manifold incorporates a ion exchange separation system in the carrier stream. The decolorisation of gallocyanine due to its oxidation was used to monitor the reaction by spectrophotometry at 524 nm. The variables which affected the reaction rate were fully investigated. By this method cerium(4) can be determined in the range of 0.30-10.0 μg with a limit of detection of 0.25 μg. The relative standard deviation for ten replicate determinations of 1.0 μg of cerium(4) was 1.8 %

  8. Standard practice for The separation of americium from plutonium by ion exchange

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This practice describes the use of an ion exchange technique to separate plutonium from solutions containing low concentrations of americium prior to measurement of the 241Am by gamma counting. 1.2 This practice covers the removal of plutonium, but not all the other radioactive isotopes that may interfere in the determination of 241Am. 1.3 This practice can be used when 241Am is to be determined in samples in which the plutonium is in the form of metal, oxide, or other solid provided that the solid is appropriately sampled and dissolved (See Test Methods C758, C759, and C1168). 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  9. Simultaneous determination of sub μg·g-1 levels of nine impurities in high purity iron by horizontal cation exchange resin mini-column and ICP-atomic emission spectrometry

    International Nuclear Information System (INIS)

    Inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been applied to the simultaneous determination of trace impurities in high purity iron after simultaneous separation. Sub μg·g-1 levels of Ca, Cd, Co, Cu, Mg, Mn, Ni, Pb and Zn in high purity iron which had been dissolved in hydrofluoric acid and hydrogen peroxide were separated from the iron matrix using a horizontal cation exchange resin mini-column. Flow rates and flow directions of solutions through the mini-column were controlled by a peristaltic pump. Adsorbed elements on the resin mini-column were rapidly eluted using a reverse flow of the eluant against the flow for the adsorption. The eluted elements were determined by ICP-AES using an internal standard method and good results were obtained. A 100-fold enrichment of analytes was obtained with this preconcentration system using 1 g of the sample in comparison with an ordinary sample solution in which 0.5 g of the sample was dissolved in 100 cm3 without separation. (author)

  10. Proceedings of the Efficient Separations and Processing Cross-Cutting Program Annual Technical Exchange Meeting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-02-01

    This document contains summaries of technology development presented at the 1995 Efficient Separations and Processing Cross-Cutting Program (ESP) Annual Technical Exchange Meeting. The ESP is sponsored by the US Department of Energy`s Office of Environmental Management (EM), Office of Technology Development. The meeting is held annually to promote a free exchange of ideas among technology developers, potential users (for example, EM focus areas), and other interested parties within EM. During this meeting, developers of ESP-funded technologies describe the problems and needs addressed by their technologies; the technical approach, accomplishments, and resolution of issues; the strategy and schedule for commercialization; and evolving potential applications. Presenters are asked to address the following areas: Target waste management problem, waste stream, or data need; scientific background and technical approach; technical accomplishments and resolution of technical issues; schedule and strategy for commercializing and implementing the technology or acquiring needed data; potential alternate applications of the technology or data, including outside of DOE/EM. The meeting is not a program review of the individual tasks or subtasks; but instead focuses on the technical aspects and implementation of ESP-sponsored technology or data. The meeting is also attended by members of the ESP Technical Review Team, who have the opportunity at that time to review the ESP as a whole.

  11. Proceedings of the Efficient Separations and Processing Cross-Cutting Program Annual Technical Exchange Meeting

    International Nuclear Information System (INIS)

    This document contains summaries of technology development presented at the 1995 Efficient Separations and Processing Cross-Cutting Program (ESP) Annual Technical Exchange Meeting. The ESP is sponsored by the US Department of Energy's Office of Environmental Management (EM), Office of Technology Development. The meeting is held annually to promote a free exchange of ideas among technology developers, potential users (for example, EM focus areas), and other interested parties within EM. During this meeting, developers of ESP-funded technologies describe the problems and needs addressed by their technologies; the technical approach, accomplishments, and resolution of issues; the strategy and schedule for commercialization; and evolving potential applications. Presenters are asked to address the following areas: Target waste management problem, waste stream, or data need; scientific background and technical approach; technical accomplishments and resolution of technical issues; schedule and strategy for commercializing and implementing the technology or acquiring needed data; potential alternate applications of the technology or data, including outside of DOE/EM. The meeting is not a program review of the individual tasks or subtasks; but instead focuses on the technical aspects and implementation of ESP-sponsored technology or data. The meeting is also attended by members of the ESP Technical Review Team, who have the opportunity at that time to review the ESP as a whole

  12. Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

    International Nuclear Information System (INIS)

    Clays and clay rocks are considered viable geotechnical barriers in radioactive waste disposal. One reason for this is the propensity for cation exchange reactions in clay minerals to retard the migration of radionuclides. Although another retardation mechanism, namely the incorporation of radionuclides into sulfate or carbonate solid solutions, has been known for a long time, only recently has it been examined systematically. In this work, we investigate the competitive effect of both mechanisms on the transport of radium (Ra) in the near-field of a low- and intermediate level nuclear waste repository. In our idealized geochemical model, numerical simulations show that barium (Ba) and strontium (Sr) needed for Ra sulfate solid solutions also partition to the cation exchange sites of montmorillonite (Mont), which is the major mineral constituent of bentonite that is used for tunnel backfill. At high Mont content, most Ra tends to attach to Mont, while incorporation of Ra in sulfate solid solutions is more important at low Monte content. To explore the effect of the Mont content on the transport of radium, a multi-component reactive transport model was developed and implemented in the scientific software OpenGeoSys-GEM. It was found that a decrease of fixation capacity due to low Mont content is compensated by the formation of solid solutions and that the migration distance of aqueous Ra is similar at different Mont/water ratios. (author)

  13. Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals.

    Science.gov (United States)

    Jang, Youngjin; Yanover, Diana; Čapek, Richard Karel; Shapiro, Arthur; Grumbach, Nathan; Kauffmann, Yaron; Sashchiuk, Aldona; Lifshitz, Efrat

    2016-07-01

    Controlling the synthesis of narrow band gap semiconductor nanocrystals (NCs) with a high-quality surface is of prime importance for scientific and technological interests. This Letter presents facile solution-phase syntheses of SnTe NCs and their corresponding core/shell heterostructures. Here, we synthesized monodisperse and highly crystalline SnTe NCs by employing an inexpensive, nontoxic precursor, SnCl2, the reactivity of which was enhanced by adding a reducing agent, 1,2-hexadecanediol. Moreover, we developed a synthesis procedure for the formation of SnTe-based core/shell NCs by combining the cation exchange and the Kirkendall effect. The cation exchange of Sn(2+) by Cd(2+) at the surface allowed primarily the formation of SnTe/CdTe core/shell NCs. Further continuation of the reaction promoted an intensive diffusion of the Cd(2+) ions, which via the Kirkendall effect led to the formation of the inverted CdTe/SnTe core/shell NCs. PMID:27331900

  14. Fabrication, characterization and photocatalytic properties of Ag/AgI/BiOI heteronanostructures supported on rectorite via a cation-exchange method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yunfang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Jianzhang, E-mail: fangjzh@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China); Lu, Shaoyou [Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Wu, Yan; Chen, Dazhi; Huang, Liyan [Institute of Engineering Technology of Guangdong Province, Key Laboratory of Water Environmental Pollution Control of Guangdong Province, Guangzhou 510440 (China); Xu, Weicheng; Zhu, Ximiao [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Zhanqiang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

    2015-04-15

    Highlights: • Ag/AgI/BiOI-rectorite was prepared by twice cation-exchange process. • Ag/AgI/BiOI-rectorite photocatalyst possessed SPR and adsorption capacity. • Ag/AgI/BiOI-rectorite exhibited highly photocatalytic activity. • Trapped holes and ·O{sub 2}{sup −} were formed active species in the photocatalytic system. - Abstract: In this work, a new plasmonic photocatalyst Ag/AgI/BiOI-rectorite was prepared via a cation exchange process. The photocatalyst had been characterized by X-ray powder diffraction (XRD), Raman spectra, nitrogen sorption (BET), field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity, which was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation, was enhanced significantly by loading Ag/AgI/BiOI nanoparticles onto rectorite. The photogenerated holes and superoxide radical (·O{sub 2}{sup −}) were both formed as active species for the photocatalytic reactions under visible light irradiation. The existence of metallic Ag particles, which possess the surface plasmon resonance effect, acted as an indispensable role in the photocatalytic reaction.

  15. chemical studies and sorption behavior of some hazardous metal ions on polyacrylamide stannic (IV) molybdophosphate as 'organic - inorganic' composite cation - exchanger

    International Nuclear Information System (INIS)

    compsite materials formed by the combination of multivalent metal acid salts and organic polymers provide a new class of (organic-inorganic) hypride ion exchangers with better mechanical and granulometric properties, good ion-exchange capacity, higher chemical and radiation stabilites, reproducibility and selectivity for heavy metals. this material was characterized using X-ray (XRD and XRF), IR, TGA-DTA and total elemental analysis studies. on the basis of distribution studies, the material has been found to be highly selective for pb(II). thermodynamic parameters (i.e δG0, δ S0 and δH0) have also been calculated for the adsorption of Pb2+, Cs+, Fe3+, Cd2+, Cu+2, Zn2+, Co2+ and Eu3+ions on polyacrylamide Sn(IV) molybdophosphate showing that the overall adsorption process is spontaneous endothermic. the mechanism of diffusion of Fe3+, Co2+, Cu+2, Zn2+, Cd2+, Cs+, Pb2+ and Eu3+ in the H-form of polyacrylamide Sn(IV) molybdophosphate composite as cation exchanger was studied as a function of particle size, concentration of the exchanging ions, reaction temperature, dring temperature and pH. the exchange rate was controlled by particle diffusion mechanism as a limited batch techneque and is confirmed from straight lines of B versus 1/r2 polts. the values of diffusion coefficients, activation energy and entropy of activation were calculated and their significance was discussed. the data obtained have been comared with that reported for other organic and inorganic exchangers.

  16. Cation exchange applications of synthetic tobermorite for the immobilization and solidification of cesium and strontium in cement matrix

    Indian Academy of Sciences (India)

    O P Shrivastava; Rashmi Shrivastava

    2000-12-01

    Immobilization and solidification of hazardous cations like Cs137 and Sr90 are required while handling the radioactive waste of nuclear power plants. Efforts are on to find a fail proof method of safe disposal of nuclear wastes. In this context, various materials like borosilicate glass, zeolites, cements and synthetic rocks have been tried by several workers. This communication deals with the synthesis, characterization, cesium uptake capacity and leaching behaviour of synthetic alumina-substituted calcium silicate hydroxy hydrate, which are close to that obtained for the natural mineral, 11 Å tobermorite. The synthetic mineral show cation selectivity for Cs+ in presence of 500–1000 times concentrated solutions of Na+ , K+ , Mg2+, Ca2+ , Ba2+ and Sr2+. Although the ordinary portland cement (OPC) which is often used in waste management operations alone holds negligible amounts of Cs+ and Sr2+, the addition of alumina-substituted tobermorite to OPC enhances the retention power of cement matrix by drastically lowering the leach rate of cations.

  17. Separation of Ofloxacin and Its Six Related Substances Enantiomers by Chiral Ligand-Exchange Chromatography.

    Science.gov (United States)

    Liang, Xinlei; Zhao, Longshan; Deng, Miaoduo; Liu, Lijie; Ma, Yongfu; Guo, Xingjie

    2015-11-01

    A chiral ligand-exchange high-performance liquid chromatography method was developed for the enantioseparation of ofloxacin and its six related substances termed impurities A, B, C, D, E, and F. The separation was performed on a conventional C18 column. Different organic modifiers, copper salts, amino acids, the ratio of Cu(2+) to amino acid, pH of aqueous phase, and column temperature were optimized. The optimal mobile phase conditions were methanol-water systems consisting of 5 mmol/L copper sulfate and 10 mmol/L L-isoleucine (L-Ile). Under such conditions, good enantioseparation of ofloxacin and impurities A, C, E, and F could be observed with resolutions (RS ) of 3.54, 1.97, 3.21, 3.50, and 2.12, respectively. On the relationship between the thermodynamic parameters and structures of analytes, the mechanism of chiral recognition was investigated. It was concluded that ofloxacin and impurities A, C, E, and F were all enthalpically driven enantioseparation and that low column temperature was beneficial to enantioseparation. Furthermore, the structure-separation relationship of these analytes is also discussed.

  18. Separation of Fluoride Ions in an Electrolytic Cell by Using an AnionExchange Membrane

    International Nuclear Information System (INIS)

    Separation of fluoride ions in an electrolytic cell with an anionexchange membrane which is so-called an electrodialysis process has beenperformed. The experiment have been taken place in room temperature in anelectrolytic cell made by plexiglas consisted on anode and cathode chambersseparated by an anion exchange membrane in dimension of 4 x 4 cm. The carbonand stainless steel are applied as an anode and platinum as s' cathode. Theanolyte is a HNO3 0.3 M solution, while a solution of NaF 0.3 M, and amixture of NaF 0.3 M containing uranyl nitrate solution for separating offluoride ions and uranium are used as a catholyte. The distance between theelectrode and the membrane is 1.5 cm and this distance is kept constant. Theparameters observed are the current voltage, cathode applied, and uraniumconcentration. For the solution without uranium, the results show that thefluoride ions transferred are around 50 % using carbon as a cathode for 3hours and the voltage of 10 volts, while for SS as a cathode are around 93 %.For the solution containing uranium, the fluoride ions transferred are around78 % for 3.5 hours and the uranium ions remain in the catholyte in which mostof them are as 8 yellow deposit of Na2U2O7 on the cathode surface andothers are as a white precipitate of NaUF5 on the bottom of the cathodechamber. (author)

  19. SEPARATION AND PURIFICATION OF LIGNIN BY MEANS OF ION EXCHANGE PROCESS

    Institute of Scientific and Technical Information of China (English)

    XUHede; LIANGHao; 等

    1993-01-01

    The effect of resin structure on desalination of lignin solution was investigated,the optimal structure of resin is as follows;cross linking degree as 4%,ratio of cationogen to anionogen is near 1.with such resin the desalination of lignin was produced very well because the resin has both molecule sieving and ion retardation properties.The sulfonation degress of lignin and total salt content of lignin solution were determinred with ion exchange technique,the relative error less than 1%.The salt content of small molecule in the lignin solution was calculated from sulfonation degree of lignin and total salt.Among gel and macroporous resins the best separation of lignin from reducing sugar was achieved with interpenetrating sulfonated resin 2×1.5×1.The separation of lignin with interpenetrating resin was carried out simultaneously with fractionation of lignin,the effect of fractionation with macroporous sulfonated resin is better than that with interpenetrating resin,but the former has a definite sorption of lignin which decreased the recovery of lignin.

  20. Photoexcitation and ionization in carbon dioxide - Theoretical studies in the separated-channel static-exchange approximation

    Science.gov (United States)

    Padial, N.; Csanak, G.; Mckoy, B. V.; Langhoff, P. W.

    1981-01-01

    Vertical-electronic static-exchange photoexcitation and ionization cross sections are reported which provide a first approximation to the complete dipole spectrum of CO2. Separated-channel static-exchange calculations of vertical-electronic transition energies and oscillator strengths, and Stieltjes-Chebyshev moment methods were used in the development. Detailed comparisons were made of the static-exchange excitation and ionization spectra with photoabsorption, electron-impact excitation, and quantum-defect estimates of discrete transition energies and intensities, and with partial-channel photoionization cross sections obtained from fluorescence measurements and from tunable-source and (e, 2e) photoelectron spectroscopy. Results show that the separate-channel static-exchange approximation is generally satisfactory in CO2.

  1. The Selective Separation of Anions and Cations in Nuclear Waste Using Commercially Available Molecular Recognition Technology (MRT) Products

    Energy Technology Data Exchange (ETDEWEB)

    Izatt, S. R.; Bruening, R. L.; Krakowiak, K. E.; Izatt, R. M.

    2003-02-25

    This paper describes the use of some of IBC's SuperLig{reg_sign}, MacroLig{reg_sign}, and AnaLig{reg_sign} molecular recognition technology products to effectively and selectively separate and recover cesium, technetium, strontium, and radium from radioactive waste solutions. Distinct advantages are given over conventional separation techniques. Separations are described and results given for the target ions over chemically similar ions often present at much higher concentrations. The separations are performed in solutions of either high or low pH and usually containing high concentrations of salts. Other separations involving components of radioactive and mixed waste are noted.

  2. Rapid chiral separation and impurity determination of levofloxacin by ligand-exchange chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hongyuan [Center for Advanced Bioseparation Technology, Department of Chemical Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Row, Kyung Ho [Center for Advanced Bioseparation Technology, Department of Chemical Engineering, Inha University, Incheon 402-751 (Korea, Republic of)]. E-mail: rowkho@inha.ac.kr

    2007-02-12

    A sensitive, simple, and accurate method for determination of levofloxacin and its (R)-enantiomer was developed to determine the chiral impurity of levofloxacin in Cravit Tablets material by ligand-exchange high performance liquid chromatography. The effects of different kinds of ligands, concentration of ligands in mobile phase, organic modifier, pH of mobile phase, and temperature on enantioseparation were investigated and evaluated. Chiral separation was performed on a conventional C{sub 18} column, where the mobile phase consisted of a methanol-water solution (containing10 mmol L{sup -1} L-leucine and 5 mmol L{sup -1} copper sulfate) (88:12, v/v) and its flow-rate was set at 1.0 mL min{sup -1}. The conventional C{sub 18} column offers baseline separation of two enantiomers with a resolution of 2.4 in less than 20 min. Thermodynamic data ({delta}{delta}H and {delta}{delta}S) obtained by Van't Hoff plots revealed the chiral separation is an enthalpy-controlled process. The standard curves showed excellent linearity over the concentration range from 0.5 to 400 mg L{sup -1} for levofloxacin and its (R)-enantiomer. The linear correlation equations are: y = 1.33 x 10{sup 5} x + 6297 (r = 0.9991) and y = 1.34 x 10{sup 5} x + 3565 (r = 0.9997), respectively. The relative standard deviation (RSD) of the method was below 2.3% (n = 3)

  3. Vibrations and instabilities of thin rectangular plates separated by fluid medium with applications to the plate type heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Gi-Man, Kim [Kum-Oh National Univ., Taegu (Korea, Republic of)

    1994-12-31

    Due to the prohibition law for using preon gas, many items in engineering field, specially heat exchanger, should be redesigned. The newly designed heat exchanger such a plate type heat exchanger is known to have a good efficiency in exchanging heat. From view of structures of a plate type heat exchanger, thin tube are used instead of circular pipe and the path of the fluid is developed for the high efficiency of the heat exchange by varying the array of tubes. The principal problem in the design of the plate heat exchanger is the potentiality of structural instabilities due to the fluid loading effect during operations. Excessive plate deflections would eventually result in permanent deformation or collapse which would cause an obstruction of the fluid flow in the narrow channels. In this study, a fluid-structural interaction model was developed to investigate analytically the static and dynamic instabilities that have been observed in flat plate heat exchanger. The model consist of two flat plates separated by water. The effects of the internal fluid in the channel was studied. As results, the natural frequency coefficients were investigated for the plate aspect ratios, channel heights, and boundary conditions. For the design criteria in plate type heat exchanger, the critical flow velocities which cause the responses of a plate were defined for divergence, resonance and flutter phenomena. (author). 25 refs. 2 tabs. 48 figs.

  4. Dynamic separation of Szilard-Chalmers reaction products applied to the trioxalatochromium ion adsorbed on anionic exchange resin

    International Nuclear Information System (INIS)

    A method of dynamic elution of recoiled 51Cr+3, formed by the Szilard-Chalmers reaction during the irradiation of trioxalatochromium ion adsorbed on anionic exchange resin is presented. The influence of some factors on the separation yield of chromium-51, such as: composition, concentration and flow rate of eluent, mesh size of the resin and irradiation time are studied. The results are compardd with those obtained by the static method, in which the recoiled atom is separated from the target after irradiation. Because of the high separation yield of chromium-51, the method of dynamic separation is proposed for routine production of this elemnt, with high specific activities. (author)

  5. Development of long-lived radionuclide partitioning technology - Preparation of ion exchanges for selective separation of radioactive elements

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Si Joong; Jeong, Hae In; Shim, Min Sook [Korea University, Seoul (Korea, Republic of); Kim, Jeong [Seonam University, Namwon (Korea, Republic of)

    1995-07-01

    Ion exchanger contained nitrogen-oxygen donor macrocyclic units was synthesized, and immobilization process was carried out by adsorption of the exchanger to silica gel. The binding constants were measured with acid concentration. From the binding constants, selectivity for Pt(II) ion and acid concentration of eluents were determined. The most optimum conditions for the separation were also determined from investigating the effects of amount of immobile phase and column length. And liarit aza-crown ethers were synthesized and selectively separated Cs/Sr ion from mixed metal solution. 37= refs., 24 tabs., 40 figs. (author)

  6. Experimental Investigation on Heat Exchange and Separation Performance of an Annular Structured Internal Heat-integrated Distillation Column☆

    Institute of Scientific and Technical Information of China (English)

    Lianghua Xu; Dawei Chen; Binghai Yan; Xigang Yuan⁎

    2014-01-01

    In this paper heat exchange coefficient and separation efficiency of an annular structured internal heat-integrated distil ation column (HIDiC) were experimental y measured. About 50%heat of the inner column could be transferred to the outer column. The overall heat exchange coefficient decreased with an increase in pressure ratio of the inner column and the outer column, but was little affected by the F-factor. The increase of the pressure ratio decreased obviously the separation efficiency of the outer column but had little effect on that of the inner column.

  7. Applying reactive models to column experiments to assess the hydrogeochemistry of seawater intrusion: Optimising ACUAINTRUSION and selecting cation exchange coefficients with PHREEQC

    Science.gov (United States)

    Boluda-Botella, N.; Valdes-Abellan, J.; Pedraza, R.

    2014-03-01

    Three sets of laboratory column experimental results concerning the hydrogeochemistry of seawater intrusion have been modelled using two codes: ACUAINTRUSION (Chemical Engineering Department, University of Alicante) and PHREEQC (U.S.G.S.). These reactive models utilise the hydrodynamic parameters determined using the ACUAINTRUSION TRANSPORT software and fit the chloride breakthrough curves perfectly. The ACUAINTRUSION code was improved, and the instabilities were studied relative to the discretisation. The relative square errors were obtained using different combinations of the spatial and temporal steps: the global error for the total experimental data and the partial error for each element. Good simulations for the three experiments were obtained using the ACUAINTRUSION software with slight variations in the selectivity coefficients for both sediments determined in batch experiments with fresh water. The cation exchange parameters included in ACUAINTRUSION are those reported by the Gapon convention with modified exponents for the Ca/Mg exchange. PHREEQC simulations performed using the Gains-Thomas convention were unsatisfactory, with the exchange coefficients from the database of PHREEQC (or range), but those determined with fresh water - natural sediment allowed only an approximation to be obtained. For the treated sediment, the adjusted exchange coefficients were determined to improve the simulation and are vastly different from those from the database of PHREEQC or batch experiment values; however, these values fall in an order similar to the others determined under dynamic conditions. Different cation concentrations were simulated using two different software packages; this disparity could be attributed to the defined selectivity coefficients that affect the gypsum equilibrium. Consequently, different calculated sulphate concentrations are obtained using each type of software; a smaller mismatch was predicted using ACUAINTRUSION. In general, the presented

  8. Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation.

    Science.gov (United States)

    Yap, R K L; Whittaker, M; Diao, M; Stuetz, R M; Jefferson, B; Bulmus, V; Peirson, W L; Nguyen, A V; Henderson, R K

    2014-09-15

    Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations. PMID:24934266

  9. Self-Assembly of Nanostructured, Complex, Multi-cation Films via Spontaneous Phase Separation and Strain-driven Ordering

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Amit [ORNL; Wee, Sung Hun [ORNL; Stocks, George Malcolm [ORNL; Zuev, Yuri L [ORNL; More, Karren Leslie [ORNL; Meng, Jianyong [ORNL; Zhong, Jianxin [ORNL

    2013-01-01

    Spontaneous self-assembly of a multi-cation nanophase in another multi-cation matrix phase is a promising bottom-up approach to fabricate novel, nanocomposite structures for a range of applications. In an effort to understand the mechanisms for such self-assembly, we report on complimentary experimental and theoretical studies to first understand and then control or guide the self-assembly of insulating BaZrO3 (BZO) nanodots within REBa2Cu3O7- (RE=rare earth elements including Y, REBCO) superconducting films. It was determined that the strain field developed around BZO nanodots embedded in REBCO matrix is a key driving force dictating the self-assembly of BZO nanodots along REBCO c-axis. The size selection and spatial ordering of BZO self-assembly were simulated using thermodynamic and kinetic models. The BZO self-assembly was controllable by tuning the interphase strain field. REBCO superconducting films with BZO defects arrays self-assembled to align in both vertical (REBCO c-axis) and horizontal (REBCO ab-planes) directions, resulted in the maximized pinning and Jc performance for all field angles with smaller angular Jc anisotropy. The work has broad implications for fabrication of controlled self-assembled nanostructures for a range of applications via strain-tuning.

  10. Investigation of the swelling behavior of cationic exchange resins saturated with Na{sup +} ions in a C{sub 3}S paste

    Energy Technology Data Exchange (ETDEWEB)

    Lafond, E. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Cau Dit Coumes, C., E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Gauffinet, S. [UMR5209 Institut Carnot de Bourgogne, Université de Bourgogne Dijon, Faculté des Sciences Mirande, 9 Avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Chartier, D. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Le Bescop, P. [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France); Stefan, L. [AREVA, Back End Business Group, Dismantling & Services, 1 place Jean Millier, 92084 Paris La Défense (France); Nonat, A. [UMR5209 Institut Carnot de Bourgogne, Université de Bourgogne Dijon, Faculté des Sciences Mirande, 9 Avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2015-03-15

    Ion exchange resins (IERs) are widely used by the nuclear industry to decontaminate radioactive effluents. Spent products are usually encapsulated in cementitious materials. However, the solidified waste form can exhibit strong expansion, possibly leading to cracking, if the appropriate binder is not used. In this work, the interactions between cationic resins in the Na{sup +} form and tricalcium silicate are investigated during the early stages of hydration in order to gain a better understanding of the expansion process. It is shown that the IERs exhibit a transient swelling of small magnitude due to the decrease in the osmotic pressure of the external solution. This expansion, which occurs just after setting, is sufficient to damage the material which is poorly consolidated for several reasons: low degree of hydration, precipitation of poorly cohesive sodium-bearing C–S–H, and very heterogeneous microstructure with zones of high porosity.

  11. A fast method for the determination of Sr-90 in liquid milk by solid phase extraction with cryptand 222 on cation exchange resin

    International Nuclear Information System (INIS)

    A method for determining the activity of Sr-90 in liquid milk samples that does not require the usual drying, ashing, acid leaching and precipitation procedures is described. Two solid phase extractants are used, namely: Cryptand 222 bound to a cation exchange resin, and Eichrome Industries' Sr.Spec Resin trademark. These are applied respectively to extract Sr-90 from the milk and to isolate it in a form suitable for measurement by low-level liquid scintillation counting. The results of analyses of 1 liter milk samples contaminated with a known activity of Sr-90 agreed well with the expected values. It was also found that Sr.Spec Resin trademark can be regenerated and re-used several times. As the method requires only minimal operator skill and time, many samples can be analyzed simultaneously. (orig.)

  12. Selective separation and determination of isoproterenol on thin layers of bismuth silicate ion-exchanger

    Institute of Scientific and Technical Information of China (English)

    Vanik GHOULIPOUR; Zahra HASSANKHANI-MAJD

    2015-01-01

    A simple and sensitive method for the separation and determination of isoproterenol from other do-ping drugs has been developed on thin layers of bismuth silicate,a synthetic inorganic ion exchanger as adsor-bent in thin layer chromatography(TLC). A mixture of methanol and 0. 1 mol/L formic acid(3:7,v/v)was employed as the mobile phase. The development time was 32 min. The quantitative measurement were per-formed with a Camag TLC Scanner-3 at wavelength(λ)of 410 nm. The isoproterenol recovery in this procedure was 98. 9%. The linear correlation coefficient was greater than 0. 987 1 and the relative standard deviation (RSD)was less than 0.94. The limit of detection(LOD)and limit of quantification(LOQ)were 7.7×10-7 mol/L and 3. 85 ×10-6 mol/L,respectively. This method has been applied in the determination of isoproterenol in dosage forms and in biological fluids.

  13. Selective separation and determination of isoproterenol on thin layers of bismuth silicate ion-exchanger.

    Science.gov (United States)

    Ghoulipour Vanik; Hassankhani-Majd Zahra

    2015-06-01

    A simple and sensitive method for the separation and determination of isoproterenol from other doping drugs has been developed on thin layers of bismuth silicate, a synthetic inorganic ion exchanger as adsorbent in thin layer chromatography (TLC). A mixture of methanol and 0.1 mol/L formic acid (3:7, v/v) was employed as the mobile phase. The development time was 32 min. The quantitative measurement were performed with a Camag TLC Scanner-3 at wavelength (λ) of 410 nm. The isoproterenol recovery in this procedure was 98.9%. The linear correlation coefficient was greater than 0. 987 1 and the relative standard deviation (RSD) was less than 0.94. The limit of detection (LOD) and limit of quantification ( LOQ) were 7.7 x 10(-7) mol/L and 3.85 x 10(-6) mol/L, respectively. This method has been applied in the determination of isoproterenol in dosage forms and in biological fluids.

  14. Protein Folding-How and Why: By Hydrogen Exchange, Fragment Separation, and Mass Spectrometry.

    Science.gov (United States)

    Englander, S Walter; Mayne, Leland; Kan, Zhong-Yuan; Hu, Wenbing

    2016-07-01

    Advanced hydrogen exchange (HX) methodology can now determine the structure of protein folding intermediates and their progression in folding pathways. Key developments over time include the HX pulse labeling method with nuclear magnetic resonance analysis, the fragment separation method, the addition to it of mass spectrometric (MS) analysis, and recent improvements in the HX MS technique and data analysis. Also, the discovery of protein foldons and their role supplies an essential interpretive link. Recent work using HX pulse labeling with MS analysis finds that a number of proteins fold by stepping through a reproducible sequence of native-like intermediates in an ordered pathway. The stepwise nature of the pathway is dictated by the cooperative foldon unit construction of the protein. The pathway order is determined by a sequential stabilization principle; prior native-like structure guides the formation of adjacent native-like structure. This view does not match the funneled energy landscape paradigm of a very large number of folding tracks, which was framed before foldons were known and is more appropriate for the unguided residue-level search to surmount an initial kinetic barrier rather than for the overall unfolded-state to native-state folding pathway. PMID:27145881

  15. Effect of temperature and pH value on cation exchange performance of a natural clay for selective (Cu2þ, Co2þ) removal:Equilibrium, sorption and kinetics

    Institute of Scientific and Technical Information of China (English)

    Ramzi Chalghaf; Walid Oueslati; Marwa Ammar; Hafsia Ben Rhaiem; Abdesslem Ben Haj Amara

    2013-01-01

    This work aims at investigating the strain effect, created by varying pH solution and continuous heating cycle, on the cation exchange process in the case of Na-rich montmorillonite sample in contact with bi-ionic solution with variable concentration, saturated respectively by Co2þ and Cu2þ cations. The ionic exchange process is characterized using XRD analysis obtained through the comparison of experimental XRD patterns with calculated ones, which allowed us to determine several structural parameters related to the nature, abundance, size, position and organization of exchangeable cation and water molecule in the interlamellar space along the cn axis. Indeed, the proposed theoretical models, for the stressed samples, show that the structure presents an interstratified hydration character and proves the coexistence of more than two ‘‘crystallite’’ specie in the structure. The perturbation types have an obvious effect on the selective exchange process for all stressed samples, where the interlayer space is characterized by the coexistence of more one exchangeable cation.

  16. Hydrogeochemical evolution of confined groundwater in northeastern Osaka Basin, Japan: estimation of confined groundwater flux based on a cation exchange mass balance method

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, Masaru [Department of Geosystem Sciences, College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo 156-8550 (Japan)]. E-mail: yamanaka@chs.nihon-u.ac.jp; Nakano, Takanori [Research Institute for Humanity and Nature, Kamigyo-ku, Kyoto 602-0878 (Japan); Tase, Norio [Institute of Geoscience, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan)

    2005-02-01

    A confined aquifer system has developed in argillaceous marine and freshwater sediments of Pliocene-Holocene age in the northeastern Osaka Basin (NEOB) in central Japan. The shallow groundwater (<100 m) in the system is recharged in a northern hilly to mountainous area with dominantly Ca-HCO{sub 3} type water, which changes as it flows toward the SW to Mg-HCO{sub 3} type and then to Na-HCO{sub 3} type water. Comparison of the chemical and Sr isotopic compositions of the groundwater with those of the bulk and exchangeable components of the underground sediments indicates that elements leached from the sediments contribute negligibly to the NEOB aquifer system. Moreover, model calculations show that contributions of paleo-seawater in the deep horizon and of river water at the surface are not major factors of chemical change of the groundwater. Instead, the zonal pattern of the HCO{sub 3}-dominant groundwater is caused by the loss of Ca{sup 2+} from the water as it is exchanged for Mg{sup 2+} in clays, followed by loss of Mg + Ca as they are exchanged for Na + K in clays between the Ca-HCO{sub 3} type recharge water and the exchangeable cations in the clay layers, which were initially enriched in Na{sup +}. Part of this process was reproduced in a chromatographic experiment in which Na type water with high {sup 87}Sr/{sup 86}Sr was obtained from Mg type water with low {sup 87}Sr/{sup 86}Sr by passing it through marine clay packed in a column. The flux of recharge water into the confined aquifer system according to this chromatographic model is estimated to be 0.99 mm/day, which is compatible with the average recharge flux to unconfined groundwater in Japan (1 mm/day)

  17. Selective sorption of lead, cadmium and zinc ions by a polymeric cation exchanger containing nano-Zr(HPO3S)2.

    Science.gov (United States)

    Zhang, Qingrui; Pan, Bingcai; Pan, Bingjun; Zhang, Weiming; Jia, Kun; Zhang, Quanxing

    2008-06-01

    A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard.

  18. Preparation and characterization of electrically conducting polypyrrole Sn(IV phosphate cation-exchanger and its application as Mn(II ion selective membrane electrode

    Directory of Open Access Journals (Sweden)

    A.A. Khan

    2011-10-01

    Full Text Available Polypyrrole Sn(IV phosphate, an organic–inorganic composite cation-exchanger was synthesized via sol-gel mixing of an organic polymer, polypyrrole, into the matrices of the inorganic precipitate of Sn(IV phosphate. The physico-chemical properties of the material were determined using Atomic Absorption Spectrometry (AAS, CHN elemental analysis (inductively coupled plasma mass spectrometry, ICP-MS, UV–VIS spectrophotometry, FTIR (Fourier Transform Infra-Red, SEM (Scanning Electron Microscopy, TGA–DTA (Thermogravimetric Analysis–Differential Thermal Analysis, and XRD (X-ray diffraction. Ion-exchange behavior was observed to characterize the material. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ion Mn2+. Due to its selective nature, the material was used as an electroactive component for the construction of an ion-selective membrane electrode. The proposed electrode shows fairly good discrimination of mercury ion over several other inorganic ions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations for Mn(II in water.

  19. Selective sorption of lead, cadmium and zinc ions by a polymeric cation exchanger containing nano-Zr(HPO3S)2.

    Science.gov (United States)

    Zhang, Qingrui; Pan, Bingcai; Pan, Bingjun; Zhang, Weiming; Jia, Kun; Zhang, Quanxing

    2008-06-01

    A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard. PMID:18589978

  20. Evaluation of chelating ion-exchange resins for separating Cr(III) from industrial effluents.

    Science.gov (United States)

    Cavaco, Sofia A; Fernandes, Sandra; Augusto, Cátia M; Quina, Margarida J; Gando-Ferreira, Licínio M

    2009-09-30

    In this study two chelating resins containing iminodiacetic acid groups (Amberlite IRC 748 and Diaion CR 11) and a chelating resin based on sulfonic and diphosphonic acid groups (Diphonix) were investigated in order to separate Cr(III) from industrial effluents produced in hard and decorative electroplating. Samples of two industrial plants were characterized during a period of about one year and a half in terms of the metals content (Cr, Cu, Na, Ca, Fe and Ni), Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Chemical Oxygen Demand (COD) and pH. Some of the physical properties of the resins, namely the moisture content, apparent density, intraparticle porosity and the particle size distribution were also evaluated. To quantify the sorption capacity of the resins, batch experiments were performed using synthetic solutions of Cr(III), as well as solutions of Fe in the case of Diphonix. The Langmuir and Langmuir-Freundlich isotherms enabled a good description of the ion-exchange equilibrium data, and the maximum sorption capacity determined for Amberlite and Diaion was 3.6 mequiv./g(dry resin). For Diphonix that parameter was 3.4 mequiv./g(dry resin). The Diphonix resin exhibits a high selectivity for transition metals (Fe, Ni) over the chromium trivalent. Therefore, it was screened as the most suitable for selectively removing those metal impurities from chromium electroplating effluents. For this resin, the sorption capacity is strongly dependent on the initial pH of the solution. Though, high regeneration efficiencies of Diphonix for stripping Cr(III) were found by using a mixture of NaOH/H(2)O(2). The mathematical model tested for describing the dynamics of the process allowed a good fitting to the experimental data and enabled the estimation of effective pore diffusivity of Cr(III). The saturations of Diphonix with industrial effluents demonstrated that the breakthrough capacity of the resin is affected by the presence of other species in solution

  1. Reillex/trademark/ HPQ: A new, macroporous polyvinylpyridine resin for separating plutonium using nitrate anion exchange

    International Nuclear Information System (INIS)

    Anion exchange in nitric acid is the major aqueous process used to recover and purify plutonium from impure scrap materials. Most strong-base anion exchange resins incorporate a styrene-divinylbenzene copolymer. A newly available, macroporous anion exchange resin based on a copolymer of 1-methyl-4-vinylpyridine and divinylbenzene has been evaluated. Comparative data for Pu(IV) sorption kinetics and capacity are presented for this new resin and two other commonly used anion exchange resins. The new resin offers high capacity and rapid sorption kinetics for Pu(IV) from nitric acid, as well as greater stability to chemical and radiolytic degradation. 8 refs., 12 figs

  2. Use of Cation Exchange Resins for Production of U{sub 3}O{sub 8} Suitable for the Al-U{sub 3}O{sub 8} Powder Metallurgy Process

    Energy Technology Data Exchange (ETDEWEB)

    Mosley, W.C.

    2001-09-17

    This report describes the production of U{sub 3}O{sub 8} powders from three types of cation exchange resins: Dowex 50W, a strong acid, sulfonate resin; AG MP-50, a macroporous form of sulfonate resin; and Bio-Rex 70, a weak acid, carboxylic resin.

  3. Dowex anion exchanger-loaded-baker's yeast as bi-functionalized biosorbents for selective extraction of anionic and cationic mercury(II) species

    International Nuclear Information System (INIS)

    Dowex anion exchanger-immobilized-baker's yeast [Dae-yeast] were synthesized and potentially applied as environmental friendly biosorbents to evaluate the up-take process of anionic and cationic mercury(II) species as well as other metal ions. Optimization of mass ratio of Dowex anion exchanger versus yeast (1:1-1:10) in presence of various interacting buffer solutions (pH 4.0-9.0) was performed and evaluated. Surface modification of [Dae-yeast] was characterized by scanning electron microscopy (SEM) and infrared spectroscopy. The maximum metal biosorption capacity values of [Dae-yeast] towards mercury(II) were found in the range of 0.800-0.960, 0.840-0.950 and 0.730-0.900 mmol g-1 in presence of buffer solutions pH 2.0, 4.0 and 7.0, respectively. Three possible and different mechanisms are proposed to account for the biosorption of mercury and mercuric species under these three buffering conditions based on ion exchange, ion pair and chelation interaction processes. Factors affecting biosorption of mercury from aqueous medium including the pH effect of aqueous solutions (1.0-7.0), shaking time (1-30 min) and interfering ions were searched. The potential applications of modified biosorbents for selective biosorption and extraction of mercury from different real matrices including dental filling waste materials, industrial waste water samples and mercury lamp waste materials were also explored. The results denote to excellent percentage extraction values, from nitric acid as the dissolution solvent with a pH 2.0, as determined in the range of 90.77-97.91 ± 3.00-5.00%, 90.00-93.40 ± 4.00-5.00% and 92.31-100.00 ± 3.00-4.00% for the three tested samples, respectively.

  4. Cationic polyelectrolyte induced separation of some inorganic contaminants and their mixture (zirconium silicate, kaolin, K-feldspar, zinc oxide) as well as of the paraffin oil from water.

    Science.gov (United States)

    Ghimici, Luminita

    2016-03-15

    The flocculation efficiency of a cationic polyelectrolyte with quaternary ammonium salt groups in the backbone, namely PCA5 was evaluated on zirconium silicate (kreutzonit), kaolin, K- feldspar and zinc oxide (ZnO) suspensions prepared either with each pollutant or with their mixture. The effect of several parameters such as settling time, polymer dose and the pollutant type on the separation efficacy was evaluated and followed by optical density and zeta potential measurements. Except for ZnO, the interactions between PCA5 and suspended particles led to low residual turbidity values (around 4% for kreutzonit, 5% for kaolin and 8% for K-feldspar) as well as to the reduction of flocs settling time (from 1200 min to 30 min and 120 min in case of kaolinit and K-feldspar, respectively), that meant a high efficiency in their separation. The negative value of the zeta potential and flocs size measurements, at the optimum polymer dose, point to contribution from charge patch mechanism for the particles flocculation. A good efficiency of PCA5 in separation of paraffin oil (a minimum residual turbidity of 9.8%) has been also found. PMID:26716571

  5. Squalamine, a novel cationic steroid, specifically inhibits the brush-border Na+/H+ exchanger isoform NHE3.

    Science.gov (United States)

    Akhter, S; Nath, S K; Tse, C M; Williams, J; Zasloff, M; Donowitz, M

    1999-01-01

    Squalamine, an endogenous molecule found in the liver and other tissues of Squalus acanthias, has antibiotic properties and causes changes in endothelial cell shape. The latter suggested that its potential targets might include transport proteins that control cell volume or cell shape. The effect of purified squalamine was examined on cloned Na+/H+ exchanger isoforms NHE1, NHE2, and NHE3 stably transfected in PS120 fibroblasts. Squalamine (1-h pretreatment) decreased the maximal velocity of rabbit NHE3 in a concentration-dependent manner (13, 47, and 57% inhibition with 3, 5, and 7 micrograms/ml, respectively) and also increased K'[H+]i. Squalamine did not affect rabbit NHE1 or NHE2 function. The inhibitory effect of squalamine was 1) time dependent, with no effect of immediate addition and maximum effect with 1 h of exposure, and 2) fully reversible. Squalamine pretreatment of the ileum for 60 min inhibited brush-border membrane vesicle Na+/H+ activity by 51%. Further investigation into the mechanism of squalamine's effects showed that squalamine required the COOH-terminal 76 amino acids of NHE3. Squalamine had no cytotoxic effect at the concentrations studied, as indicated by monitoring lactate dehydrogenase release. These results indicate that squalamine 1) is a specific inhibitor of the brush-border NHE isoform NHE3 and not NHE1 or NHE2, 2) acts in a nontoxic and fully reversible manner, and 3) has a delayed effect, indicating that it may influence brush-border Na+/H+ exchanger function indirectly, through an intracellular signaling pathway or by acting as an intracellular modulator. PMID:9886929

  6. Catalysis in a Cage: Condition-Dependent Speciation and Dynamics of Exchanged Cu Cations in SSZ-13 Zeolites.

    Science.gov (United States)

    Paolucci, Christopher; Parekh, Atish A; Khurana, Ishant; Di Iorio, John R; Li, Hui; Albarracin Caballero, Jonatan D; Shih, Arthur J; Anggara, Trunojoyo; Delgass, W Nicholas; Miller, Jeffrey T; Ribeiro, Fabio H; Gounder, Rajamani; Schneider, William F

    2016-05-11

    The relationships among the macroscopic compositional parameters of a Cu-exchanged SSZ-13 zeolite catalyst, the types and numbers of Cu active sites, and activity for the selective catalytic reduction (SCR) of NOx with NH3 are established through experimental interrogation and computational analysis of materials across the catalyst composition space. Density functional theory, stochastic models, and experimental characterizations demonstrate that within the synthesis protocols applied here and across Si:Al ratios, the volumetric density of six-membered-rings (6MR) containing two Al (2Al sites) is consistent with a random Al siting in the SSZ-13 lattice subject to Löwenstein's rule. Further, exchanged Cu(II) ions first populate these 2Al sites before populating remaining unpaired, or 1Al, sites as Cu(II)OH. These sites are distinguished and enumerated ex situ through vibrational and X-ray absorption spectroscopies (XAS) and chemical titrations. In situ and operando XAS follow Cu oxidation state and coordination environment as a function of environmental conditions including low-temperature (473 K) SCR catalysis and are rationalized through first-principles thermodynamics and ab initio molecular dynamics. Experiment and theory together reveal that the Cu sites respond sensitively to exposure conditions, and in particular that Cu species are solvated and mobilized by NH3 under SCR conditions. While Cu sites are spectroscopically and chemically distinct away from these conditions, they exhibit similar turnover rates, apparent activation energies and apparent reaction orders at the SCR conditions, even on zeolite frameworks other than SSZ13. PMID:27070199

  7. Onset of size independent cationic exchange in nano-sized CoFe{sub 2}O{sub 4} induced by electronic excitation

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hemaunt [Department of Physics, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 (India); Singh, Jitendra Pal, E-mail: jitendra_singh2029@rediffmail.com [Advanced Analysis Canter, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Srivastava, R.C.; Negi, P.; Agrawal, H.M. [Department of Physics, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 (India); Asokan, Kandasami [Materials Science Division, Inter University Accelerator Centre, New Delhi 110067 (India); Won, Sung Ok [Advanced Analysis Canter, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Chae, Keun Hwa, E-mail: khchae@kist.re.kr [Advanced Analysis Canter, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2015-10-05

    Highlights: • Electronic excitation induced crystalline order in CoFe{sub 2}O{sub 4}. • No change of metallic valence state under dense electronic excitation. • Size independent control of cations in CoFe{sub 2}O{sub 4}. - Abstract: Present work investigates electronic excitation induced cationic exchange phenomena in nano-sized cobalt ferrites using Mössabaur and X-ray absorption spectroscopies. The electronic excitations were produced by irradiation of 100 MeV O{sup +7} at different fluences ranging from 1 × 10{sup 11} to 1 × 10{sup 14} ions/cm{sup 2}. Cubic spinel phase of cobalt ferrite remains preserved after irradiation. However, attributes of crystalline disorder were observed in irradiated materials. Crystallite size remain almost same for pristine and irradiated materials. X-ray absorption fine structure measurements show the preservation of valence state and spin state of metal ions under intense electronic excitation. These measurements also envisage bond breaking process induced by the electronic excitation. Mössbauer spectroscopic measurements also corroborate with the fine structure measurements that the valence state of Fe remains same after irradiation. Paramagnetic doublet which presents in the Mössabaur spectrum of pristine material disappears after irradiation, showing the evolution of irradiation induced magnetic ordering. Fe{sup 3+} ion increases with irradiation at octahedral site of spinel lattice. Magnetization of the material slightly increases after irradiation at the fluence of 5 × 10{sup 13} and 1 × 10{sup 14} ions/cm{sup 2}.

  8. Nearly 1000 Protein Identifications from 50 ng of Xenopus laevis Zygote Homogenate Using Online Sample Preparation on a Strong Cation Exchange Monolith Based Microreactor Coupled with Capillary Zone Electrophoresis.

    Science.gov (United States)

    Zhang, Zhenbin; Sun, Liangliang; Zhu, Guijie; Cox, Olivia F; Huber, Paul W; Dovichi, Norman J

    2016-01-01

    A sulfonate-silica hybrid strong cation exchange monolith microreactor was synthesized and coupled to a linear polyacrylamide coated capillary for online sample preparation and capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) bottom-up proteomic analysis. The protein sample was loaded onto the microreactor in an acidic buffer. After online reduction, alkylation, and digestion with trypsin, the digests were eluted with 200 mM ammonium bicarbonate at pH 8.2 for CZE-MS/MS analysis using 1 M acetic acid as the background electrolyte. This combination of basic elution and acidic background electrolytes results in both sample stacking and formation of a dynamic pH junction. 369 protein groups and 1274 peptides were identified from 50 ng of Xenopus laevis zygote homogenate, which is comparable with an offline sample preparation method, but the time required for sample preparation was decreased from over 24 h to less than 40 min. Dramatically improved performance was produced by coupling the reactor to a longer separation capillary (∼100 cm) and a Q Exactive HF mass spectrometer. 975 protein groups and 3749 peptides were identified from 50 ng of Xenopus protein using the online sample preparation method. PMID:26670623

  9. Reversed phase and cation exchange liquid chromatography with spectrophotometric and elemental/molecular mass spectrometric detection for S-adenosyl methionine/S-adenosyl homocysteine ratios as methylation index in cell cultures of ovarian cancer.

    Science.gov (United States)

    Iglesias González, T; Cinti, M; Montes-Bayón, M; Fernández de la Campa, M R; Blanco-González, E

    2015-05-01

    S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are essential compounds in the carbon metabolic cycle that have clinical implications in a broad range of disease conditions. The measurement of the ratio SAM/SAH also called methylation index, has become a way of monitoring the DNA methylation of a cell which is an epigenetic event with important clinical implications in diagnosis; therefore the development of suitable methods to accurately quantify these compounds is mandatory. This work illustrates the comparison of three independent methods for the determination of the methylation index, all of them based on the chromatographic separation of the two species (SAM and SAH) using either ion-pairing reversed phase or cation exchange chromatography. The species detection was conducted using either molecular absorption spectrophotometry (HPLC-UV) or mass spectrometry with electrospray (ESI-MS/MS) as ionization source or inductively coupled plasma (DF-ICP-MS) by monitoring the S-atom contained in both analytes. The analytical performance characteristics of the three methods were critically compared obtaining best features for the combination of reversed phase HPLC with ESI-MS in the MRM mode. In this case, detection limits of about 0.5ngmL(-1) for both targeted analytes permitted the application of the designed strategy to evaluate the effect of cisplatin on the changes of the methylation index among epithelial ovarian cancer cell lines sensitive (A2780) and resistant (A2780CIS) to this drug after exposition to cisplatin.

  10. Influence of cation substitution and activator site exchange on the photoluminescence properties of Eu3+-doped quaternary pyrochlore oxides.

    Science.gov (United States)

    Mahesh, S K; Rao, P Prabhakar; Thomas, Mariyam; Francis, T Linda; Koshy, Peter

    2013-12-01

    Stannate-based pyrochlore-type red phosphors CaGd(1-x)SnNbO7:xEu(3+), Ca(1-y)Sr(y)Gd(1-x)SnNbO7:xEu(3+), and Ca(0.8-x)Sr0.2GdSnNbO(7+δ): xEu(3+) were prepared via conventional solid-state method. Influence of cation substitution and activator site control on the photoluminescence properties of these phosphors are elucidated using powder X-ray diffraction, Rietveld analysis, Raman spectrum analysis, and photoluminescence excitation and emission spectra. The Eu(3+) luminescence in quaternary pyrochlore lattice exemplifies as a very good structural probe for the detection of short-range disorder in the lattice, which otherwise is not detected by normal powder X-ray diffraction technique. The Eu(3+) emission due to magnetic dipole transition ((5)D0-(7)F1 MD) is modified with the increase in europium concentration in the quaternary pyrochlore red phosphors. (5)D0-(7)F1 MD transition splitting is not observable for low Eu(3+) doping because of the short-range disorder in the pyrochlore lattice. Appearance of narrow peaks in Raman spectra confirms that short-range disorder in the crystal lattice disappears with progressive europium doping. By using Sr as a network modifier ion in place of Ca we were able to increase the f-f transition intensities and europium quenching concentration. The influence of effective positive charge of the central Eu(3+) ions when it replaces a metal ion having lower oxidation state such as Ca(2+) was also investigated. The relative intensities of A1g (∼500 cm(-1)) and F2g (∼330 cm(-1)) Raman vibrational modes get inverted when Eu(3+) ions replaces Ca(2+) ions instead of Gd(3+) as trivalent europium ions can attract the electron cloud of oxygen ions strongly in comparison with divalent calcium ions. The influence of positive charge effect of Eu(3+) in Ca0.7Sr0.2GdSnNbO7+δ:0.1Eu(3+) phosphor is greatly strengthened the charge transfer band and (7)F0-(5)L6 transition intensities than that of the Ca0.8Sr0.2Gd0.9SnNbO7:0.1Eu(3+) phosphor. Our

  11. Synthesis, characterization and analytical application of nano-composite cation-exchange material, poly-o-toluidine Ce(IV) phosphate: Its application in making Cd(II) ion selective membrane electrode

    Science.gov (United States)

    Khan, Asif Ali; Akhtar, Tabassum

    2011-03-01

    An organic-inorganic composite, poly-o-toluidine Ce(IV) phosphate was chemically synthesized by mixing ortho-toluidine into the gel of Ce(IV) phosphate in different mixing volume ratios. Effect of eluant concentration, elution behavior and pH-titration studies were carried out to understand the ion-exchange capabilities. The physico-chemical properties of the material were determined using AAS, CHN elemental analysis, UV-VIS spectrophotometry, FTIR, SEM/EDX, TGA-DTA, TEM (Transmission electron microscopy), XRD and SEM studies. The distribution studies revealed that the cation-exchange material is highly selective for Cd(II). Due to selective nature of the cation-exchanger, ion selective membrane electrode was fabricated for the determination of Cd(ІІ) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.

  12. The separation of 65Zn from 113Sn and 207Bi radioisotopes by amalgam exchange and electro-analytical methods

    International Nuclear Information System (INIS)

    In this study, by using amalgam-exchange and electro-analytical methods, the separation of 65Zn radioisotope from a solution containing either one or both of the 113Sn and 207Bi radioisotopes were investigated. The radioisotopes were drawn into Zn-amalgam from the solution at first, and then 65Zn was recovered from the amalgam through back-electrolysis. No detectable contamination was observed and the recovery efficiency was found to be around 75%. (author)

  13. Cation locations and dislocations in zeolites

    Science.gov (United States)

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  14. Recovery of soil pH, cation-exchange capacity and the saturation of exchange sites from stemflow-induced soil acidification in three Swedish beech (Fagus sylvatica L.) forests

    International Nuclear Information System (INIS)

    Stemflow water acidifies the soil in beech stands impacted by atmospheric deposition. To investigate whether the soil recovers from acidification, stemflow was experimentally removed. A horizon material was sampled at a distance of 10-250 cm from the stems. Before the onset of the experiment, there were stemflow-induced gradients in the saturation of exchange sites with K+, H+ and Na+ that were larger near the stems, while the pHKCl, the cation-exchange capacity, and the saturation with Ca2+, Mg2+ and Mn2+ were smaller. After 8 yrs of recovery, the pHKCl and the saturation with Ca2+ and Mg2+ had increased close to the stems, while the saturation with Na+, H+, Mn2+ and Fe2+ and the C/N ratio had decreased. With some exceptions, e.g. base saturation, the recovery was not complete after 8 yrs. Soil far from stems had also changed similarly, probably because of the ongoing decrease in overall deposition in southern Sweden

  15. 2-Acrylamido-2-methyl-1-propanesulfonic Acid Grafted Poly(vinylidene fluoride-co-hexafluoropropylene)-Based Acid-/Oxidative-Resistant Cation Exchange for Membrane Electrolysis.

    Science.gov (United States)

    Pandey, Ravi P; Das, Arindam K; Shahi, Vinod K

    2015-12-30

    For developing acid-/oxidative-resistant aliphatic-polymer-based cation-exchange membrane (CEM), macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) was carried out by controlled chemical grafting of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). To introduce the unsaturation suitable for chemical grafting, dehydrofluorination of commercially available PVDF-co-HFP was achieved under alkaline medium. Sulfonated copolymer (SCP) was prepared by the free radical copolymerization of dehydofluorinated PVDF-co-HFP (DHPVDF-co-HFP) and AMPS in the presence of free radical initiator. Prepared SCP-based CEMs were analyzed for their morphological characteristics, ion-exchange capacity (IEC), water uptake, conductivity, and stabilities (mechanical, chemical, and thermal) in comparison with state-of-art Nafion117 membrane. High bound water content avoids the membrane dehydration, and most optimal (SCP-1.33) membrane exhibited about ∼2.5-fold high bound water content in comparison with that of Nafion117 membrane. Bunsen reaction of iodine-sulfur (I-S) was successfully performed by direct-contact-mode membrane electrolysis in a two-compartment electrolytic cell using different SCP membranes. High current efficiency (83-99%) confirmed absence of any side reaction and 328.05 kJ mol-H2(-1) energy was required for to produce 1 mol of H2 by electrolytic cell with SCP-1.33 membrane. In spite of low conductivity for reported SCP membrane in comparison with that of Nafion117 membrane, SCP-1.33 membrane was assessed as suitable candidate for electrolysis because of its low-cost nature and excellent stabilities in highly acidic environment may be due to partial fluorinated segments in the membrane structure. PMID:26642107

  16. Water-Chemistry Evolution and Modeling of Radionuclide Sorption and Cation Exchange during Inundation of Frenchman Flat Playa

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald; Cablk, Mary; LeFebre, Karen; Fenstermaker, Lynn; Decker, David

    2013-08-01

    dioxide and calcite; dissolution of sodium chloride, gypsum, and composite volcanic glass; and precipitation of composite clay and quartz represented changes in water as it disappeared from the playa. This modeling provided an understanding of the water-soil geochemical environment, which was then used to evaluate the potential mobility of residual radionuclides into the playa soils by water. Because there is no information on the chemical forms of anthropogenic radionuclides in Frenchman Flat playa soil, it was assumed that soil radionuclides go into solution when the playa is inundated. In mobility modeling, a select group of radionuclides were allowed to sorb onto, or exchange with, playa soil minerals to evaluate the likelihood that the radionuclides would be removed from water during playa inundation. Radionuclide mobility modeling suggested that there would be minimal sorption or exchange of several important radionuclides (uranium, cesium, and technetium) with playa minerals such that they may be mobile in water when the playa is inundated and could infiltrate into the subsurface. Mobility modeling also showed that plutonium may be much less mobile because of sorption onto calcite, but the amount of reactive surface area of playa soil calcite is highly uncertain. Plutonium is also known to sorb onto colloidal particles suspended in water, suspended colloidal particles will move with the water, providing a mechanism to redistribute plutonium when Frenchman Flat playa is inundated. Water chemistry, stable isotopes, and geochemical modeling showed that residual radionuclides in Frenchman Flat playa soils could be mobilized in water when the playa is inundated with precipitation. Also, there is potential for these radionuclides to infiltrate into the subsurface with water. As a result of the information obtained both during this study and the conclusions drawn from it, additional data collection, investigation, and modeling are recommended. Specifically: sampling the

  17. Production of {sup 61}Cu using natural cobalt target and its separation using ascorbic acid and common anion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sujata Saha; Chattopadhyay, Sankha; Barua, Luna [Radiopharmaceuticals Laboratory, Board of Radiation and Isotope Technology (BRIT), Variable Energy Cyclotron Centre (VECC), Kolkata 700064 (India); Das, Malay Kanti, E-mail: mkdas@vecc.gov.in [Radiopharmaceuticals Laboratory, Board of Radiation and Isotope Technology (BRIT), Variable Energy Cyclotron Centre (VECC), Kolkata 700064 (India)

    2012-02-15

    {sup 61}Cu was produced by {sup nat}Co({alpha}, xn){sup 61}Cu reaction. {sup 61}Cu production yield was 89.5 MBq/{mu}Ah (2.42 mCi/{mu}Ah) at the end of irradiation (EOI). A simple radiochemical separation method using anion exchange resin and ascorbic acid has been employed to separate the product radionuclide from inactive target material and co-produced non-isotopic impurities. The radiochemical separation yield was about 90%. Radiochemical purity of {sup 61}Cu was >99% 1 h after EOI. Final product was suitable for making complex with N{sub 2}S{sub 2} type of ligands. - Highlights: Black-Right-Pointing-Pointer High purity, no-carrier added {sup 61}Cu produced from natural cobalt target. Black-Right-Pointing-Pointer {sup 61}Cu separated from impurities using anion exchange resin and ascorbic acid. Black-Right-Pointing-Pointer {sup 61}Cu preparation was successfully used to label N{sub 2}S{sub 2}-type of ligand.

  18. Separation of stable isotopes of alkali and alkaline earth metals in chemical exchange systems with crown ethers

    International Nuclear Information System (INIS)

    Chemical isotope exchange in two-phase water - organic systems Men+ (water) - MeLn+ (org), where Me = Li, Ca, K, Mg; L = crown ethers with 5 to 6 oxygen atoms in macrocyclic ring; org = CHCl3, CH2Cl2 has been studied. The process of isotope separation has been realized by extraction chromatography. The chromatographic column contained a fixed aqueous phase. The organic solution of metal complex with crown ether was eluted through the column. On contact with the fixed aqueous phase in the course of chromatography, metal salt reextraction occurred and interphase isotope exchange between aqueous and organic phases resulted. Isotope separation factors in these systems were in the range of: 1.0032 - 1.020 (6Li/7Li), 1.0016 - 1.0038 (40Ca/44Ca), 1.0007 - 1.0011 (39K/41K), 1.0014 - 1.0044 (24Mg/26Mg). The theoretical model has been proposed to interpret the high separation factors in crown ether extraction systems. According to this model, the potential in such systems has a very flat bottom. This type of potential results in weakening the force field and decreasing of β-factor (i.e., (s/s')f) in spite of comparatively high energy of complexation. This model can interpret both high separation factors and their strong dependence on the type of crown ether. (author)

  19. Cation exchange-based post-processing of 68Ga-eluate: A comparison of three solvent systems for labelling of DOTATOC, NO2APBP and DATAm

    International Nuclear Information System (INIS)

    Interest in 68Ga has led to a number of innovations for its provision suitable for clinical application. Several post-processing methods are available to reduce eluate volume and remove metal trace impurities. In this work three cation exchange resin based post-processing methods (acetone, ethanol and NaCl) have been compared, using three model precursors (DOTATOC, NO2APBP and DATAm), in terms of labelling yield and reproducibility. The acetone and ethanol based methods provided greater reproducibility and yields that makes subsequent purification unnecessary. - Highlights: • Comparison of different 68Ga post-processing methods through the labelling of DOTATOC, NO2APBP and DATAm. • Comparison in terms of radiochemical yield, reproducibility and radiolysis. • Ethanol and acetone post-processed 68Ga facilitated the highest yields and reproducibility. • Ethanol post-processed 68Ga resulted in the lowest degree of radiolysis of 68Ga-DOTATOC. • Experimenting with different post-processing methods is an important optimisation step. • Ethanol-post processed 68Ga is suitable for clinical application

  20. [Effects of biochar amendment on cropland soil bulk density, cation exchange capacity, and particulate organic matter content in the North China Plain].

    Science.gov (United States)

    Chen, Hong-Xia; Du, Zhang-Liu; Guo, Wei; Zhang, Qing-Zhong

    2011-11-01

    A 3-year field experiment with randomized block design was conducted to study the effects of biochar amendment on the soil bulk density, cation exchange capacity (CEC), and particulate organic matter C (POM-C) and N (POM-N) contents in a high-yielding cropland in the North China Plain. Four treatments were installed, i.e., chemical NPK (CK), chemical NPK plus 2250 kg x hm(-2) of biochar (C1), chemical NPK plus 4500 kg x hm(-2) of biochar (C2), and 750 kg x hm(-2) of biochar-based slow release fertilizer (CN). Comparing with CK, treatments C1 and C2 significantly decreased the bulk density of 0-7.5 cm soil layer by 4.5% and 6.0%, respectively, and the treatments with biochar amendment increased the CEC in 0-15 cm soil layer, with an increment of 24.5% in treatment C2. Biochar amendment also increased the C (POM-C) and N (POM-N) contents in 0-7.5 cm soil layer, e.g., the POM-C and N contents in treatment C1 and C2 were 250% and 85%, and 260% and 120% higher than those of the CK, respectively. After three years of biochar amendment, the soil had obvious improvement in its physical and chemical properties, and played more active roles in soil carbon sequestration and greenhouse gases emission reduction. PMID:22303671

  1. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS.

    Science.gov (United States)

    Pyo, Jae Sung

    2016-01-01

    A gas chromatography-mass spectrometry (GC-MS) method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX) cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ) of propofol was 25 ng/mL. The validated method exhibited good linearity (R (2) = 0.9989) with accuracy and precision -5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes. PMID:27597928

  2. Evaluation of ALIX as an ion exchanger for selective separation of Cs from acidic solution

    International Nuclear Information System (INIS)

    ALIX (Advance Lipophilic Ion Exchanger) is an ammonium molybdophosphate (AMP) based composite material in which AMP is encapsulated in egg box structure formed by hydrophobic polymeric inert substrate. This structure brings the high porosity and mechanical strength. ALIX is loaded with 80% (w/w) of AMP. Studies were carried out to understand the effect of void volume on distribution coefficient of Cs (KdCs). It was found that void volume does not influence the concentration of Cs. Maximum exchange capacity of Cs (CEC) was found to be 0.63 meq/gm. (author)

  3. Separation of Radioactive Elements Using Nitrogen Oxygen Donor Macrocyclic Ion Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Si Joong; Shim, Min Sook [Korea University, Seoul (Korea, Republic of); Kim, Jeong; Lee, Myung No [Seonam University, Namwon (Korea, Republic of)

    1997-07-01

    The study for the selective separation and recovery of Pd{sup 2+} ion lead to following results. The four kinds of stationary phase, SGB-NTOE, SGB-NTOT, SGB-NEOD, and SGB-NTOD, were synthesized to react NOTE, NTOT, NEOD, and NTOD with 3-glycidyloxypropyltrimethoxy silane and silica gel. Using these macrocycles, selective separation of Hg(II), Pt(II), and Pd(II) from alkali earth and transition metal ions were possible by column chromatography. Maximum separation capability was appeared in SGB-NTOT and it took 12 hours for complete separation of Pd{sup 2+} ion with the column which inner diameter was 24 cm. The results of the study for the selective separation of Cs{sup +} and Sr{sup 2+} are as follows: Sr{sup 2+} ion was effectively separated through liquid membrane with CR22BB and the relative transport ration of Sr{sup 2+}/Na{sup +} was 15. Cs{sup +} ion was effectively separated through liquid membrane with CR22BB(OH)Ph and the relative transport ration of Cs{sup +}/Na{sup +} was 3.4. 9 refs., 7 tabs., 15 figs. (author)

  4. Study of Adsorptive Ethylene/Ethane Separation with Ag+—Exchanged Resins via π—Complexation

    Institute of Scientific and Technical Information of China (English)

    WUZhongbiao; LIUYue

    2002-01-01

    Ag+-exchanged resins are prepared and studied for ethylene/ethane separation by adsorption.On Ag+-exchanged S9,at 25℃ and 0.1013MPa,the equilibrium adsorbed amount for C2H4 is 0.992mmol·g-1,and the adsorption ratio for C2H4/C2H6 is 3.56.The adsorption capacity can be restored almost completely at 25℃ and 75℃,and the desorption residual amount is less than 0.01mmol·g-1.For the adsorption consisting of physical adsorption and π-complexation with energy heterogeneity,the equilibrium data are correlated with Langmuir-Freundlich isotherm equation.Furthermore,the heat of adsorption and the overall diffusion time constants are calculated from the experimental datal.Considering all the adsorption characteristics,the application potential for industrial adsorption process is discussed.

  5. Separation of mono- and di-PEGylate of exenatide and resolution of positional isomers of mono-PEGylates by preparative ion exchange chromatography.

    Science.gov (United States)

    Nguyen, Ngoc-Thanh Thi; Lee, Jae Sun; Yun, Soi; Lee, E K

    2016-07-29

    Exenatide is a synthetic version of the 39-mer peptide of Exendin-4, which is an FDA-approved therapeutic against Type II diabetes mellitus. However, exenatide has a very short in-serum half-life and PEGylation have been performed to improve its in-serum stability. PEGylation often yields multivalent binding to non-specific residues, and the desired species should be carefully separated by chromatographies. In this study, we first devised an aqueous-phase, two-step PEGylation process. This consists of thiolation of Lys 12 and 27 residues followed by attachment of PEG-maleimide (10kD) to thiol groups. This process yields various species: mono-PEGylates with positional isomers, di-PEGylate, and other higher MW substances. A prep-grade cationic exchange chromatography (HiTrap SP) at pH 3.0 partially separated mono- and di-PEGylates based on the molar ratio of conjugated PEG and peptide and thus molecular weight of the conjugates. To further investigate the chromatographic separation of positional isomers of mono-PEGylates, we prepared two kinds of exenatide analogs by point mutation; K12C and K27C. Each analog was mono-PEGylated with very high yield (>95%). When a mixture of the two positional isomers of mono-PEGylates was applied to HiTrap SP chromatography, K12C-PEGylate and K27C-PEGylate eluted separately at 0.22M and 0.33M NaCl, respectively. When the proportions of acid and its conjugate base of the amino acid residues adjacent to the PEGylation site at pH 3.0 were analyzed, K27C-PEGylate shows stronger positive charge than K12C-PEGylate, and we propose the residence time difference between the two mono-PEGylates could be due to the charge difference. ELISA result shows that the immuno-binding activity of both analogs and their mono-PEGylates are well maintained. Furthermore, both mono-PEGylates of the analogs show higher than 50-fold improved anti-trypsin stability. We expect that mono-PEGylates of the exenatide analogs are alternatives to the conventional C40

  6. Separation of europium, cobalt and zinc on zirconium tungstate ion exchanger

    International Nuclear Information System (INIS)

    Amorphous zirconium tungstate inorganic ion-exchanger has been prepared under optimum conditions and characterized by IR, X-ray and thermal analysis. Surface area and capacity are determined. It has characteristic IR absorption peaks at 3242, 1628, 955, 868 and 432 cm-1 and is thermally stable up to 450 deg C. Its surface area was 16 m2/g with an exchange capacity of 0.541 meq/g. The sorption of radioactive europium from different media at ambient temperature by the zirconium tungstate (ZW) exchanger has been studied. The aim was to optimize the conditions for sorbing Eu from radioactive waste and cleaned the ZW from for recycling. The effect of contact time, metal concentration, pH and temperature has been measured. Percentual uptake of Eu(III) reaches 95% for HCl at pH 4 and increases with temperature indicating an endothermic sorption process. Uptake of Zn(II) and Co(II) on ZW from acetic acid was found to be 42% and 24% for cobalt and zinc, respectively. Desorption after saturation and the effect of other radioactive ions on the percentual uptake of Eu on ZW were investigated. A solution of 3M HCl releases 90%, 25% and 13% of the loaded Eu(III), Co(II) and Zn(II), respectively. (author)

  7. A novel approach to measure elemental concentrations in cation exchange resins using XRF-scanning technique, and its potential in water pollution studies

    Science.gov (United States)

    Huang, Jyh-Jaan; Lin, Sheng-Chi; Löwemark, Ludvig; Liou, Ya-Hsuan; Chang, Queenie; Chang, Tsun-Kuo; Wei, Kuo-Yen; Croudace, Ian W.

    2016-04-01

    X-ray fluorescence (XRF) core-scanning is a fast, and convenient technique to assess elemental variations for a wide variety of research topics. However, the XRF scanning counts are often considered a semi-quantitative measurement due to possible absorption or scattering caused by down core variability in physical properties. To overcome this problem and extend the applications of XRF-scanning to water pollution studies, we propose to use cation exchange resin (IR-120) as an "elemental carrier", and to analyze the resins using the Itrax-XRF core scanner. The use of resin minimizes the matrix effects during the measurements, and can be employed in the field in great numbers due to its low price. Therefore, the fast, and non-destructive XRF-scanning technique can provide a quick and economical method to analyze environmental pollution via absorption in the resin. Five standard resin samples were scanned by the Itrax-XRF core scanner at different exposure times (1 s, 5 s, 15 s, 30 s, 100 s) to allow the comparisons of scanning counts with the absolute concentrations. The regression lines and correlation coefficients of elements that are generally used in pollution studies (Ca, Ti, Cr, Ni, Cu, Zn, and Pb) were examined for the different exposure times. The result shows that within the test range (from few ppm to thousands ppm), the correlation coefficients are all higher than 0.97, even at the shortest exposure time (1 s). Therefore, we propose to use this method in the field to monitor for example sewage disposal events. The low price of resin, and fast, multi elements and precise XRF-scanning technique provide a viable, cost- and time-effective approach that allows large sample numbers to be processed. In this way, the properties and sources of wastewater pollution can be traced for the purpose of environmental monitoring and environmental forensics.

  8. Effects of nitrogen, calcium and cation exchange capacity on gum yield in Acacia senegal under plantation and savanna woodland conditions in northern Guinea savanna, Nigeria

    Directory of Open Access Journals (Sweden)

    Unanaonwi OE

    2011-08-01

    Full Text Available Several reports have indicated fertilizer application is not required for increased gum yield in Acacia senegal. This study investigated the relationships between soil properties and gum yield under plantation and savanna woodland conditions. Multi-stage sampling was used to demarcate a 900 ha plantation into 20 blocks of 45 ha, and a 300 ha savanna woodland into 10 blocks of 30 ha. Twenty sub-plots per site were randomly selected for yield assessment by tapping for gum collection, weighing, and recording yield figures in grams. Twelve soil pits were established for soil analysis. Data were analyzed using log-log correlation, and linear regressions. Plantation results showed nitrogen (r = 0.72 and Cation Exchange Capacity (r = 0.67 were positively correlated with yield, and calcium and yield were negatively correlated (r = -0.73. The plantation results indicated the coefficient of determination (R2 and standard error (SE were respectively 0.99 and 0.005 for nitrogen,0.79 and 0.024 for calcium, and 0.53 and 0.036 for CEC. Ninety-nine percent, 79%, and 53% of the variation in yield were explained by nitrogen, calcium and CEC, respectively. Under savanna woodland conditions, only nitrogen was positively correlated with yield (r = 0.65, and R2 and SE were respectively 0.70 and 0.014, with 70% of the variation in yield explained by nitrogen. Regression equations were subsequently developed to predict gum yield. Gum yield was correlated with soil chemical properties, and could be predicted based on nitrogen, calcium, and CEC values.

  9. CATION EXCHANGER1 Cosegregates with Cadmium Tolerance in the Metal Hyperaccumulator Arabidopsis halleri and Plays a Role in Limiting Oxidative Stress in Arabidopsis Spp.

    Science.gov (United States)

    Baliardini, Cecilia; Meyer, Claire-Lise; Salis, Pietrino; Saumitou-Laprade, Pierre; Verbruggen, Nathalie

    2015-09-01

    Arabidopsis halleri is a model species for the study of plant adaptation to extreme metallic conditions. In this species, cadmium (Cd) tolerance seems to be constitutive, and the mechanisms underlying the trait are still poorly understood. A previous quantitative trait loci (QTL) analysis performed on A. halleri × Arabidopsis lyrata backcross population1 identified the metal-pump gene Heavy Metal ATPase4 as the major genetic determinant for Cd tolerance. However, although necessary, Heavy Metal ATPase4 alone is not sufficient for determining this trait. After fine mapping, a gene encoding a calcium(2+)/hydrogen(+) antiporter, cation/hydrogen(+) exchanger1 (CAX1), was identified as a candidate gene for the second QTL of Cd tolerance in A. halleri. Backcross population1 individuals displaying the A. halleri allele for the CAX1 locus exhibited significantly higher CAX1 expression levels compared with the ones with the A. lyrata allele, and a positive correlation between CAX1 expression and Cd tolerance was observed. Here, we show that this QTL is conditional and that it is only detectable at low external Ca concentration. CAX1 expression in both roots and shoots was higher in A. halleri than in the close Cd-sensitive relative species A. lyrata and Arabidopsis thaliana. Moreover, CAX1 loss of function in A. thaliana led to higher Cd sensitivity at low concentration of Ca, higher sensitivity to methylviologen, and stronger accumulation of reactive oxygen species after Cd treatment. Overall, this study identifies a unique genetic determinant of Cd tolerance in the metal hyperaccumulator A. halleri and offers a new twist for the function of CAX1 in plants. PMID:26162428

  10. CATION EXCHANGER1 Cosegregates with Cadmium Tolerance in the Metal Hyperaccumulator Arabidopsis halleri and Plays a Role in Limiting Oxidative Stress in Arabidopsis Spp.1[OPEN

    Science.gov (United States)

    Baliardini, Cecilia; Meyer, Claire-Lise; Salis, Pietrino; Saumitou-Laprade, Pierre; Verbruggen, Nathalie

    2015-01-01

    Arabidopsis halleri is a model species for the study of plant adaptation to extreme metallic conditions. In this species, cadmium (Cd) tolerance seems to be constitutive, and the mechanisms underlying the trait are still poorly understood. A previous quantitative trait loci (QTL) analysis performed on A. halleri × Arabidopsis lyrata backcross population1 identified the metal-pump gene Heavy Metal ATPase4 as the major genetic determinant for Cd tolerance. However, although necessary, Heavy Metal ATPase4 alone is not sufficient for determining this trait. After fine mapping, a gene encoding a calcium2+/hydrogen+ antiporter, cation/hydrogen+ exchanger1 (CAX1), was identified as a candidate gene for the second QTL of Cd tolerance in A. halleri. Backcross population1 individuals displaying the A. halleri allele for the CAX1 locus exhibited significantly higher CAX1 expression levels compared with the ones with the A. lyrata allele, and a positive correlation between CAX1 expression and Cd tolerance was observed. Here, we show that this QTL is conditional and that it is only detectable at low external Ca concentration. CAX1 expression in both roots and shoots was higher in A. halleri than in the close Cd-sensitive relative species A. lyrata and Arabidopsis thaliana. Moreover, CAX1 loss of function in A. thaliana led to higher Cd sensitivity at low concentration of Ca, higher sensitivity to methylviologen, and stronger accumulation of reactive oxygen species after Cd treatment. Overall, this study identifies a unique genetic determinant of Cd tolerance in the metal hyperaccumulator A. halleri and offers a new twist for the function of CAX1 in plants. PMID:26162428

  11. 襄阳市农田土壤阳离子交换量的测定及分析%Measurement and analysis of farmland soil cation exchange capacity in Xiangyang

    Institute of Scientific and Technical Information of China (English)

    赵翔

    2016-01-01

    Soil cation exchange capacity ( CEC) can reflect the level of soil fertility, fertilizer retention capacity and buffering capacity. Throughinvestigation, sampling and laboratory analysis of soil cation exchange capacity of 16 spot in Xiangyang city, we discovered that the CEC of Xiangyang soil are concentrated in the 15-20 cmol/kg , which belongs to the medium fertility soil. At the same time, through the determination of soil physiochemical indexes, such as the content of soil organic matter,PH value, we discovery that they are very good cor-relation to soil cation exchange capacity.%土壤阳离子交换量CEC能够综合反映土壤肥力水平、保肥能力和缓冲能力。通过对襄阳市16个点位农田土壤实地调查、采集及实验室分析测定土壤阳离子交换量,发现襄阳市农田土壤阳离子交换量多集中在15-20 cmol/kg,属于中等偏上保肥能力土壤,同时通过测定土壤有机质含量,PH值等土壤理化指标,发现与土壤阳离子交换量存在很好的相关性。

  12. An improved ion-exchange separation of rare-earth elements for spectrographic analysis

    International Nuclear Information System (INIS)

    Rare-earth elements are separated from scandium and base metals by adsorption onto anion resin BIORAD AG1-X8 in the nitrate form from a mixture of 5 per cent 7M nitric acid and 95 per cent methanol. The yttrium subgroup is eluted with a mixture of 45 per cent 7M nitric acid and 55 per cent methanol, followed by elution of the cerium subgroup with 8M nitric acid. This separation facilitates the determination of the traces of the heavier yttrium subgroup of rare-earth elements

  13. Effect of alcohols on separation behavior of rare earth elements using benzimidazole-type anion-exchange resin in nitric acid solutions

    International Nuclear Information System (INIS)

    Chromatographic separation experiments of trivalent rare earth elements were performed using benzimidazole type anion-exchange resin in nitric/alcohol mixed solvent systems at room temperature. As a result, it was found those trivalent rare earth elements are able to be separated mutually in a 20% HNO3 and 80% MeOH mixed solvent. Based on these results, we systematically examined using various alcohols to make clear the role of alcohols in anion-exchange reactions at various temperatures. (author)

  14. Reversible CO binding enables tunable CO/H₂ and CO/N₂ separations in metal-organic frameworks with exposed divalent metal cations.

    Science.gov (United States)

    Bloch, Eric D; Hudson, Matthew R; Mason, Jarad A; Chavan, Sachin; Crocellà, Valentina; Howe, Joshua D; Lee, Kyuho; Dzubak, Allison L; Queen, Wendy L; Zadrozny, Joseph M; Geier, Stephen J; Lin, Li-Chiang; Gagliardi, Laura; Smit, Berend; Neaton, Jeffrey B; Bordiga, Silvia; Brown, Craig M; Long, Jeffrey R

    2014-07-30

    Six metal-organic frameworks of the M2(dobdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) structure type are demonstrated to bind carbon monoxide reversibly and at high capacity. Infrared spectra indicate that, upon coordination of CO to the divalent metal cations lining the pores within these frameworks, the C-O stretching frequency is blue-shifted, consistent with nonclassical metal-CO interactions. Structure determinations reveal M-CO distances ranging from 2.09(2) Å for M = Ni to 2.49(1) Å for M = Zn and M-C-O angles ranging from 161.2(7)° for M = Mg to 176.9(6)° for M = Fe. Electronic structure calculations employing density functional theory (DFT) resulted in good agreement with the trends apparent in the infrared spectra and crystal structures. These results represent the first crystallographically characterized magnesium and zinc carbonyl compounds and the first high-spin manganese(II), iron(II), cobalt(II), and nickel(II) carbonyl species. Adsorption isotherms indicate reversible adsorption, with capacities for the Fe, Co, and Ni frameworks approaching one CO per metal cation site at 1 bar, corresponding to loadings as high as 6.0 mmol/g and 157 cm(3)/cm(3). The six frameworks display (negative) isosteric heats of CO adsorption ranging from 52.7 to 27.2 kJ/mol along the series Ni > Co > Fe > Mg > Mn > Zn, following the Irving-Williams stability order. The reversible CO binding suggests that these frameworks may be of utility for the separation of CO from various industrial gas mixtures, including CO/H2 and CO/N2. Selectivities determined from gas adsorption isotherm data using ideal adsorbed solution theory (IAST) over a range of gas compositions at 1 bar and 298 K indicate that all six M2(dobdc) frameworks could potentially be used as solid adsorbents to replace current cryogenic distillation technologies, with the choice of M dictating adsorbent regeneration energy and the level of purity of the resulting gases.

  15. Direct determination of seleno-amino acids in biological tissues by anion-exchange separation and electrochemical detection.

    Science.gov (United States)

    Cavalli, S; Cardellicchio, N

    1995-07-01

    Several studies have described the determination of selenium in protein extracts from tissues of marine or terrestrial animals, but have not identified the different chemical forms of selenium that are present. Selenium may be present as seleno-amino acids. Selenocysteine, for example, is a normal component of glutathione peroxidase, an antioxidant enzyme which may behave like other antioxidants, such as vitamin E, protecting tissues against methylmercury toxicity. The present study illustrates a method for the characterization of seleno-amino acids, such as selenocysteine and selenomethionine, in proteins extracted from the liver of marine mammals. The mechanism of detoxification of methylmercury, which involves seleno-compounds, is identified. The analytical determination was carried out using high-performance anion-exchange chromatography coupled with integrated pulsed amperometric detection (HPAEC-IPAD). This method allows the direct determination of underivatized amino acids, eliminating the procedure of pre- or postcolumn derivatization. The chromatographic separation was carried out on an anion-exchange column using a quaternary gradient elution. In order to optimize this method, interferences of amino acids and the influence of pH and ionic strength on the separation and electrochemical detection were studied. The IPAD response for the direct detection of amino acids is optimum at pH > 11. The detection limit (S/N = 3) for selenocysteine was found to be 450 micrograms/l. The application of this method for the identification of seleno-amino acids in protein hydrolysates is also shown. PMID:7640774

  16. 非水毛细管电泳分离碱金属、碱土金属和铵离子的机理研究%Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    刘红霞; 宋鹃梅; 张书胜; MACKA Miroslav; HADDAD Paul R

    2004-01-01

    Capillary electrophoresis ( CE ) has rapidly gained great interests among researchers in many different fields. One of these areas is the separation of small ions such as inorganic cations, anions, and low Mr organic molecules However, as the separation of ions

  17. Separations on a cellulose exchanger with salicylic acid as functional group

    International Nuclear Information System (INIS)

    The use of a cellulose compound containing salicylic acid as functional group (capacity 0.6 mequ./g) for different problems is described. The seperations Fe3+/Cu2+ and Cu2+/Ni2+ in aqueous solutions are achieved smoothly at pH 2 and 2.5 resp. In organic solvents (pyridine) copper ions are separated from copper complexes as shown by the examples Cu2+/[Cu(mnt)2]2- (mnt = maleonitril-1,2-dithiolate) and Cu2+/dibenzo[b.i.][5.9.14.18]tetraazacyclotetradecene-copper [Cu(chel)]. The complex [Cu(mnt)2]2- can be labelled with Cu-64 on a separation column, whereas [Cu-(chel)] is substition inert. (orig.)

  18. Extensive separations (CLEAN) processing strategy compared to TRUEX strategy and sludge wash ion exchange

    International Nuclear Information System (INIS)

    Numerous pretreatment flowsheets have been proposed for processing the radioactive wastes in Hanford's 177 underground storage tanks. The CLEAN Option is examined along with two other flowsheet alternatives to quantify the trade-off of greater capital equipment and operating costs for aggressive separations with the reduced waste disposal costs and decreased environmental/health risks. The effect on the volume of HLW glass product and radiotoxicity of the LLW glass or grout product is predicted with current assumptions about waste characteristics and separations processes using a mass balance model. The prediction is made on three principal processing options: washing of tank wastes with removal of cesium and technetium from the supernatant, with washed solids routed directly to the glass (referred to as the Sludge Wash C processing strategy); the previous steps plus dissolution of the solids and removal of transuranic (TRU) elements, uranium, and strontium using solvent extraction processes (referred to as the Transuranic Extraction Option C (TRUEX-C) processing strategy); and an aggressive yet feasible processing strategy for separating the waste components to meet several main goals or objectives (referred to as the CLEAN Option processing strategy), such as the LLW is required to meet the US Nuclear Regulatory Commission Class A limits; concentrations of technetium, iodine, and uranium are reduced as low as reasonably achievable; and HLW will be contained within 1,000 borosilicate glass canisters that meet current Hanford Waste Vitrification Plant glass specifications

  19. Extensive separations (CLEAN) processing strategy compared to TRUEX strategy and sludge wash ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Knutson, B.J.; Jansen, G.; Zimmerman, B.D.; Seeman, S.E. [Westinghouse Hanford Co., Richland, WA (United States); Lauerhass, L.; Hoza, M. [Pacific Northwest Lab., Richland, WA (United States)

    1994-08-01

    Numerous pretreatment flowsheets have been proposed for processing the radioactive wastes in Hanford`s 177 underground storage tanks. The CLEAN Option is examined along with two other flowsheet alternatives to quantify the trade-off of greater capital equipment and operating costs for aggressive separations with the reduced waste disposal costs and decreased environmental/health risks. The effect on the volume of HLW glass product and radiotoxicity of the LLW glass or grout product is predicted with current assumptions about waste characteristics and separations processes using a mass balance model. The prediction is made on three principal processing options: washing of tank wastes with removal of cesium and technetium from the supernatant, with washed solids routed directly to the glass (referred to as the Sludge Wash C processing strategy); the previous steps plus dissolution of the solids and removal of transuranic (TRU) elements, uranium, and strontium using solvent extraction processes (referred to as the Transuranic Extraction Option C (TRUEX-C) processing strategy); and an aggressive yet feasible processing strategy for separating the waste components to meet several main goals or objectives (referred to as the CLEAN Option processing strategy), such as the LLW is required to meet the US Nuclear Regulatory Commission Class A limits; concentrations of technetium, iodine, and uranium are reduced as low as reasonably achievable; and HLW will be contained within 1,000 borosilicate glass canisters that meet current Hanford Waste Vitrification Plant glass specifications.

  20. Chemical studies on polyaniline titanotungstate as a new composite cation exchanger and its analytical applications for removal of cesium from aqueous solutions

    International Nuclear Information System (INIS)

    Polyaniline titanotungstate has been synthesized by incorporation of organic polymer polyaniline into the inorganic precipitate of titanotungstate. This material was characterized using IR, X-Ray, SEM and DTA-TGA analysis. The influences of initial concentration of metal ions, particle size and temperature have been reported. The material stability was investigated in water, acids, alkaline solutions, and at high temperature up to 850 degree C. Ion-exchange capacity and distribution coefficients (Kd) for ten metal ions have been determined. It was found that the polyaniline titanotungstate has high affinity and high selectivity for Cs+. The material has high separation for Cs+ ion from other metal ions. The comparison of composite (PATiW) and inorganic material (TiW) was studied and indicated that the composite material is better than the inorganic one in selectivity of Cs+. Thermodynamic parameter of Cs+ exchange process, such as changes in Gibbs free energy (δGo), enthalpy (δHo), and entropy (δSo) have been calculated. It was found that numerical value of δG decrease with an increase in temperature,indicating that the sorption reaction of adsorbent was spontaneous and more favorable at higher temperature. The positive value of δHo corresponds to the endothermic nature of sorption processes and suggested that chemisorptions were the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of Cs+ was evaluated for the pseudo first-order, pseudo second-order, homogeneous particle diffusion, shell model and intraparticle diffusion models. The results showed that Cs+ is sorption onto PATiW and TiW with particle diffusion mechanism. Self diffusion coefficient (Di), Activation energy (Ea) and entropy (δS*) of activation were also computed from thelinearized form of Arrhenius equation. Column studies in acid and alkaline solutions were studied. A kinetic study for removal cesium from milk was investigated.

  1. Radium-228 determination of natural waters via concentration on manganese dioxide and separation using Diphonix ion exchange resin.

    Science.gov (United States)

    Nour, S; El-Sharkawy, A; Burnett, W C; Horwitz, E P

    2004-12-01

    The objective of this work was to establish a new procedure for 228Ra determination of natural waters via preconcentration of radium on MnO2 and separation of its daughter, 228Ac, using Diphonix ion exchange resin. Following removal of potential interferences via passage through an initial Diphonix Resin column, the first daughter of 228Ra, 228Ac, is isolated by chromatographic separation via a second Diphonix column. A holding time of > 30 h for 228Ac ingrowth in between the two column separations ensures secular equilibrium. Barium-133 is used as a yield tracer. Actinium-228 is eluted from the second Diphonix Resin with 5 ml 1M 1-Hydroxyethane-1,1-diphosphonic acid (HEDPA) and quantified by addition of scintillation cocktail and LSC counting. Radium (and 133Ba) from the load and rinse solutions from the 2nd Diphonix column may be prepared for alpha spectrometry (for determination of 223Ra, 224Ra, and 226Ra) by BaSO4 microprecipitation and filtration. Decontamination tests indicate that U, Th, and Ra series nuclides do not interfere with these measurements, although high contents of 90Sr (90Y) require additional treatment for accurate measurement of 228Ra. Addition of stable Sr as a "hold back" carrier during the initial MnO2 preconcentration step was shown to remove most 90Sr interference.

  2. Effect of alcohols on separation behavior of rare earth elements using benzimidazole-type anion-exchange resin in nitric acid solutions

    International Nuclear Information System (INIS)

    The mutual separation of rare earth elements based on the ion exchange chromatography has been studied. The effect of alcohols on separation behavior of rare earth elements using the benzimidazole-type anion-exchange resin embedded in high-porous silica beads was investigated in nitric acid/alcohol mixed solvent systems. It was confirmed that the mutual separation of rare earth elements is possible by using our proposed methods. It was found that the distribution coefficients of rare earth elements depend on the corresponding alcoholic relative permittivity and on the steric hindrance due to the hydrophobic interaction among each alcoholic molecule. (author)

  3. 阳离子交换树脂催化水解大豆糖蜜的研究%Hydrolysis of soy molasses catalyzed by cation exchange resin

    Institute of Scientific and Technical Information of China (English)

    郭紫光; 张永忠

    2011-01-01

    Strong acid styrene cation exchange resin was used to catalyze the hydrolysis of soy molasses.Through single factor and orthogonal experiments, the best conditions were determined as follows: ratio of liquid to solid 3: 1, time 120 min, temperature 60 ℃, concentration of substrate 0.2 g/mL. After hydrolysis under the optimum conditions, the ratio of reducing sugar to total sugar was 0.91, reducing sugar yield was 36.85% and reducing sugar content reached 368.46 mg/g, which was 4. 4 times higher than that before hydrolysis ( 83.93 mg/g). When the molasses was hydrolyzed at the optimal conditions, the reducing sugar yield of the resin catalysis method was almost the same with that of the acid catalysis method, but the resin method avoided the high temperature and low pH, and the resin method had the advantages of easy operation and less wastewater emissions.%采用强酸性苯乙烯系阳离子交换树脂催化水解大豆糖蜜.通过单因素及正交试验得到优化条件为:水解时间120 min,水解温度60℃,液固比3:1,底物质量浓度0.2 g/mL.水解后还原糖与总糖比率达到0.91,还原糖得率为36.85%,还原糖含量达到368.46 mg/g,比水解前的83.93 mg/g提高了3.4倍.与传统酸催化法对比得知,分别在最优条件下水解大豆糖蜜,还原糖得率相差无几,但树脂法避免了高温,pH低,操作简便,废水排放量减少.

  4. 阳离子交换树脂催化合成富马酸二丁酯%Synthesis of dibutyl fumarate on cation exchange resin

    Institute of Scientific and Technical Information of China (English)

    申红; 丁斌; 郝凤岭; 刘艳杰

    2011-01-01

    以阳离子交换树脂(NKC-9)为催化剂、富马酸单甲酯和正丁醇为原料合成富马酸二丁酯,考察了原料配比、催化剂用量、反应时间和甲苯用量等因素对反应的影响以及催化剂的重复使用性能.最佳反应工艺条件为:n(正丁醇):n(富马酸单甲酯)=3.0∶1、w(NKC -9)=6.0%、反应温度不高于120℃、w(甲苯)=49.5%、反应时间2.5h.结果表明,在该条件下富马酸单甲酯的转化率为98.1%;催化剂经重复使用6次后,富马酸单甲酯的转化率为96.9%.阳离子交换树脂(NKC -9)具有催化活性高、稳定性好、无环境污染等优点.%Synthesis of dibutyl fumarate from monomethyl fumarate and n-butyl alcohol on cation exchange resin catalyst(NKC-9) was studied. Effects of reaction conditions,such as mole ratio of n-butyl alcohol to monomethyl fumarate,catalyst content,toluene content,and reaction time,and the reusability of the catalyst were investigated. Optimum reaction conditions were obtained, which were:n(n-butyl alcohol) : n(monomethyl fumarate) =3. 0 : 1,catalyst content 6. 0%(relative to total mass of monomethyl fumarate and n-butyl alcohol), react ion temperature ≤ 120 ℃, toluene content 49. 5%(relative to total mass of monomethyl fumarate and n-butyl alcohol), reaction time 2. 5 h. The results showed that conversion of monomethyl fumarate could reach 98. L%,and activity of catalyst was still kept at 96. 9% after being used 6 times. NKC-9 has many advantages,such as high activity,good stability and pollution-free to the environment.

  5. Tandem anion and cation exchange solid phase extraction for the enrichment of micropollutants and their transformation products from ozonation in a wastewater treatment plant.

    Science.gov (United States)

    Deeb, Ahmad A; Schmidt, Torsten C

    2016-06-01

    The presence of organic micropollutants and their transformation products (TPs) from biotic and abiotic processes in aquatic environments is receiving intense public and scientific attention. Yet a suitable sample preparation method that would enable extraction and enrichment of a wide range of such compounds from water is missing. The focus of this paper was to develop an enhanced solid phase extraction (SPE) protocol which enabled isolation of parent compounds and low molecular weight transformation products (that are produced after treatment of water with ozone) from different water matrices. Ten SPE sorbents were evaluated with regard to their ability to extract acidic, neutral, and basic compounds from water at several pH values. Highest recoveries (91-99 %) for all analytes in pure water were obtained by combining strong anion and cation exchangers of two manufacturers in a tandem mode without pH adjustment. Tandem Oasis (MAX+MCX) was finally applied to extract the spiked analytes from tap water, surface water, and several wastewater samples. The efficiency of the used SPE procedure was examined using an optimized liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method using multiple reaction monitoring (MRM) mode. The occurrence of some of the investigated TPs in environmental water matrices was proven for the first time in this study. Method quantification limits (MQLs) for all compounds ranged from 3.7 to 15.3 ng/L in all matrices. Recoveries (%RE) were between 90 and 110 %. Intraday and interday precision, expressed as relative standard deviation, varied from 0.7 to 5.9 % and 1.8 to 10.3 %, respectively. Matrix effect (%ME) evaluation demonstrated that even complex sample matrices did not show significant ion suppression or enhancement. The applicability of the method was shown during two sampling campaigns at Ruhr river and a wastewater treatment plant (WWTP) equipped with an ozonation step after regular

  6. Effects of Land Use Practices on the Organic Carbon Content, Cation Exchange Capacity and Aggregate Stability of Soils in the Catchment Zones

    Directory of Open Access Journals (Sweden)

    Mosayeb Heshmati

    2011-01-01

    Full Text Available Problem statement: Land use practice leads to changes in the physico-chemical properties of soils, such as Soil Organic Carbon (SOC, Cation Exchange Capacity (CEC and Soil Aggregate Stability (SAS that cause soil erosion. Approach: Merek catchment, Iran suffers from land degradation due to poor land use practice. A study was carried out with the objectives: (i to determine soil nutrient status in different agro-ecological zones in Merek catchment; and (ii to evaluate the influence of land use practices on SOC, CEC and SAS. Results: It was found that soil texture was silty and clay, while soil reaction was alkaline (pH was 7.75. The respective amount of carbonates was 32 and 36% in the top-soil and sub-soil respectively, indicating high level of alkalinity in the soils of the study area. The mean SAS of the surface soil layer for agriculture, rangeland and forest was 53, 61 and 64%, respectively with its mean in the topsoil of agriculture is significantly lower (P≤0.05 than the other zones. SOC level in the agriculture, rangeland and forest were 1.35, 1.56, 2.14 % in the topsoil and 1.03, 1.33 and 1.45%, in the subsoil of the respective areas. The results of t-test and ANOVA analyses showed that SOC means are significantly different from each other within soil depth and among agro-ecological zones. The CEC in the agriculture, rangeland and forest areas were 25.8, 24.6 and 35.1 cmolckg-1 for the top-soil and 31.1, 26.8 and 26.9 cmolckg-1 in the sub-soil, respectively. All the above changes are due to the negative effects of agricultural activities. Conclusion: Improper tillage practice (up-down the slope, conversion of the rangeland and forest to rain-fed areas, crop residue burning, over grazing and forest clearance contribute to reduction in SOC and SAS in the Merek catchment, Iran.

  7. Concentration and separation of vanadium from alkaline media by strong alkaline anion-exchange resin 717

    Institute of Scientific and Technical Information of China (English)

    HUANG Jinwen; SU Peng; WU Wenwei; LIAO Sen; QIN Huiquan; WU Xuehang; HE Xiaohu; TAO Liujia; FAN Yanjin

    2010-01-01

    With strong alkaline anion-exchange resin 717 as the sorbent and NaOH solution as the eluent, a study on the sorption from alkaline solution and elution of vanadium(Ⅴ), silicon(Ⅳ), and aluminium(Ⅲ) was carried out. Different parameters affecting the sorption and elution process,including temperature, pH values as well as the ratio of resin to solution, were investigated. The results show that sorption degree of vanadium(Ⅴ) increases with a decrease of pH values, and V(Ⅴ) ions are easier sorbed than Si(Ⅳ) and Al(Ⅲ) ions under the same conditions. The sorption degree of V(Ⅴ), Si(Ⅳ), and Al(Ⅲ) at pH 9.14 for 15 min are 90.6%, 33.5%, and 21.6%, respectively. Si(Ⅳ), Al(Ⅲ), and V(Ⅴ) ions sorbed on 717 resin were eluted by use of 2 mol.L-1 NaOH solution; the desorption degree of V(Ⅴ), Si(Ⅳ), and Al(Ⅲ) for 5 min are 81.7 %,99.1%, and 99.3%, respectively.

  8. Determination of thorium and uranium in activated concrete by inductively coupled plasma mass spectrometry after anion-exchange separation

    International Nuclear Information System (INIS)

    A sensitive analytical method was established for the determination of Th and U in activated concrete samples. The method combines an anion-exchange separation step with an ICP-MS determination technique. In the ICP-MS measurement, a few μg mL-1 of Al and Ca, a few ng mL-1 of Mn, La, Ce, Nd and Pb and pg mL-1amounts of Li, Zr, Nb and Ba coexisting in the anion-exchange fraction of Th and U did not interfere. No adverse interference effects were observed in real sample analyses. The obtained detection limits (3 σ, n = 10) of Th and U were 2.3 and 1.8 pg mL -1, respectively. The analytical precisions for ca. 5 μg g -1 Th and ca. 1 μg g -1 U in real activated concrete samples were equally less than 7% RSD. The accuracies obtained by the analysis of GSJ rock standard samples were -18.1 to 0.4% for the Th determination and -14.0 to -5.7% for the U determination. The method uses the conventional absolute calibration curve. The internal standard calibration is unnecessary. (orig.)

  9. Comparison of displacement versus gradient mode for separation of a complex protein mixture by anion-exchange chromatography.

    Science.gov (United States)

    Ahrends, Robert; Lichtner, Björn; Buck, Friedrich; Hildebrand, Diana; Kotasinska, Marta; Kohlbacher, Oliver; Kwiatkowski, Marcel; Wagner, Moritz; Trusch, Maria; Schlüter, Hartmut

    2012-07-15

    Liquid chromatography is often the method of choice for the analysis of proteins in their native state. Nevertheless compared to two-dimensional electrophoresis, the resolution of common chromatographic techniques is low. Liquid chromatography in the displacement mode has previously been shown to offer higher resolution and to elute proteins in the high concentrations. In this study we compared to what extend displacement mode was a suitable alternative to gradient mode for the separation of a complex protein mixture using anion-exchange displacement chromatography and if it is therefore helpful for proteomic investigations. Hence we analyzed the qualitative protein composition of each fraction by tryptic digestion of the proteins, analysis of the tryptic peptides by liquid chromatography coupled to mass spectrometry followed by data base analysis and by measuring the elution profiles of 22 selected proteins with selected reaction monitoring mass spectrometry. In the fractions of displacement mode a significantly higher number of identified proteins (51 versus 16) was yielded in comparison to gradient mode. The resolution of displacement chromatography was slightly lower than of gradient chromatography for many but not for all proteins. The selectivities of displacement mode and gradient mode are very different. In conclusion displacement chromatography is a well suited alternative for top-down proteomic approaches which start with separating intact proteins first prior to mass spectrometric analysis of intact or digested proteins. The significant orthogonality of both modes may be used in the future for combining them in multidimensional fractionation procedures. PMID:22727752

  10. The elution of erbium from a cation exchanger bed by means of the N-hydroxyethyl-ethylene-diamine triacetic acid; Mecanismo de la elucion del erbio en un cambiador cationico con el acido n-hidroxietil-etilen-diamono-triacetico

    Energy Technology Data Exchange (ETDEWEB)

    Amer Amezaga, S.

    1963-07-01

    A physicochemical study of the phenomena resulting when erbium is eluted from a cation-exchanger bed at a steady by means of the N-hydroxyethyl-ethylene-diamine-triacetic acid (HEDTA) is made. Two different retaining beds are used, a hydrogen bed, in which no ammonium passes through, and a zinc bed, which leaks ammonium ion. Good agreement between experimental and calculated values by using the equations deduced for the concentrations of the main species has been achieved, with errors around 1-2% in most of the experiments. (Author) 69 refs.

  11. Catalytic Synthesis of N - Butyl Lactate by Strongly Acidic Cationic Exchange Resin%强酸性阳离子交换树脂催化合成乳酸正丁酯

    Institute of Scientific and Technical Information of China (English)

    熊文高; 俞善信

    2001-01-01

    N - butyl lactate was synthesized from lactic acid and n - butyl alcohol in the presence of strongly acidic cationic exchange resin. The yield of the ester can reach 99. 3% under mole ratio of lactic acid and n - butyl alcohol was 0. 1: 0.2, the amount of strongly acidic cationic exchange resin was 0. 5 g, refluxing and water seprating for 100 min. The reusability of the catalyst was studied.%在强酸性阳离子交换树脂存在下,由乳酸和正丁醇合成了乳酸正丁酯。当乳酸和正丁醇的摩尔比为1:2,强酸性阳离子交换树脂的用量0.5 g,回流分水100min时酯收率达99.3%。同时,研究了催化剂的重复使用性能。

  12. Radiochemical Study on the Separation of Chromium-51 from the Irradiated Target by Using Commercial and/or Synthesized Ion Exchanger

    International Nuclear Information System (INIS)

    This work involves the following steps:1- Preparation of Triton X-100 Cerium(IV) Phosphate (TX-100CeP) as a surface active ion exchanger or organometallic molecules. 2- Characterization of the TX-100CeP by different methods (i.e. IR, TGA/DTA X-ray diffraction, X-ray fluorescence and elemental analysis). 3- Development a method for separation and quantification of Cr(III) and Cr(VI) by using high pressure liquid chromatography (HPLC). 4- Separation of 51Cr(III) from Cr(VI) in the target of K2CrO4 on TX-100CeP and Permutit as a commercial ion exchanger. 5- Quality control on the separated 51Cr(III).

  13. Cátions trocáveis, capacidade de troca de cátions e saturação por bases em solos brasileiros adubados com composto de lixo urbano Exchangeable cations, cation exchange capacity and base saturation in Brazilian soils amended with urban waste compost

    Directory of Open Access Journals (Sweden)

    Cassio Hamilton Abreu Jr.

    2001-12-01

    Full Text Available O uso agrícola do composto de lixo, como fertilizante orgânico, além de melhorar as propriedades do solo, representa uma alternativa importante para gestão de resíduos sólidos domiciliares. Foram estudados os efeitos da aplicação do composto de lixo, proveniente da cidade de São Paulo (Usina de compostagem São Matheus, na dose de 30 g dm-3 (60 t ha-1, na presença e ausência de calcário dolomítico e adubos minerais, sobre os teores de cátions trocáveis (K+, Ca2+, Mg2+ e Na+; a capacidade de troca de cátions (CTC e a saturação por bases (V% de 21 solos ácidos e 5 solos alcalinos. Nos solos alcalinos o calcário foi substituído por gesso. O experimento foi conduzido em condições de casa de vegetação em delineamento em blocos ao acaso, com parcelas em faixas e três repetições. Nos solos ácidos, a aplicação do composto de lixo promoveu aumentos nos teores trocáveis de potássio, cálcio, magnésio e sódio, em média, de 195%, 200%, 86% e 1200%, e elevação da CTC em 42%, refletindo na V%, com aumento médio de 39%. Nos solos alcalinos, esses efeitos foram menos pronunciados, refletindo porém, em média, em aumentos da CTC em 8,4% e da V% em 2%. Os maiores efeitos sobre as propriedades químicas avaliadas foram conseqüências das aplicações do composto + adubo + calcário, nos solos ácidos, e do composto + adubo + gesso, nos solos alcalinos. A aplicação agrícola do composto de lixo urbano é viável, porém seus efeitos sobres as propriedades químicas do solo devem ser monitorados.The use of urban organic solid waste compost as organic fertilizer is an important alternative to solid waste management. This waste has been applied to agricultural lands because of the benefits in relation to soil chemical properties. A greenhouse experiment was conducted to investigate the effects of the application of urban waste compost, at the rate of 30 g dm-3 (60 t ha-1, on the contents of exchangeable cations (K+, Ca2+, Mg2

  14. Exchange of lyotropic series cations by micaceous vermiculite and its weathering products determined by electron microscopy and radiochemical analysis. Final technical report, June 1, 1965-October 31, 1978

    International Nuclear Information System (INIS)

    Micaceous vermiculite was found to be ubiquitous in soils, sediments, and aerosol mineral dusts and to adsorb fission product ions, particularly 137Cs+ and 90Sr2+. Crystallographic wedge zones (imaged by ultramicrotomy and electron microscopy) in micaceous vermiculite effected tight fixation of Cs+. Lowering of mica layer charge occurred in local areas, electronoscopically imaged by use of blister-swelling cations. Nuclear fission particle tracks of U enhanced translayer diffusion of elements, measured mica layer charge and age. Iron-aluminum hydrous oxide coatings adsorbed divalent cations of the alkaline earth, transition, and heavy metal elements from trace concentrations in the presence of 1 M NaNO3. Global deposition of dust by rainfall accounted for the wide distribution of Cs-fixing micaceous vermiculite in soils. Origin of the dust was traced through a method developed for isolation of fine quartz silt (1 to 10 μm diameter). Mass spectrometry of its 18O/16O isotopic ratios showed distinctly higher (delta18O = 17 to 22%0) and lower (delta18O = 9 to 15%0) ranges in the Northern and Southern Hemispheres, respectively. This difference was traced to the relative proportions of quartz from low-temperature authigenic (chert) vs igneous-metamorphic origin in the respective latitudes, hinging on trans-equatorial continental drift

  15. 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 ion...

  16. Huntingtin regulates Ca(2+) chemotaxis and K(+)-facilitated cAMP chemotaxis, in conjunction with the monovalent cation/H(+) exchanger Nhe1, in a model developmental system: insights into its possible role in Huntington׳s disease.

    Science.gov (United States)

    Wessels, Deborah; Lusche, Daniel F; Scherer, Amanda; Kuhl, Spencer; Myre, Michael A; Soll, David R

    2014-10-01

    Huntington׳s disease is a neurodegenerative disorder, attributable to an expanded trinucleotide repeat in the coding region of the human HTT gene, which encodes the protein huntingtin. These mutations lead to huntingtin fragment inclusions in the striatum of the brain. However, the exact function of normal huntingtin and the defect causing the disease remain obscure. Because there are indications that huntingtin plays a role in Ca(2+) homeostasis, we studied the deletion mutant of the HTT ortholog in the model developmental system Dictyostelium discoideum, in which Ca(2+) plays a role in receptor-regulated behavior related to the aggregation process that leads to multicellular morphogenesis. The D. discoideum htt(-)-mutant failed to undergo both K(+)-facilitated chemotaxis in spatial gradients of the major chemoattractant cAMP, and chemotaxis up a spatial gradient of Ca(2+), but behaved normally in Ca(2+)-facilitated cAMP chemotaxis and Ca(2+)-dependent flow-directed motility. This was the same phenotypic profile of the null mutant of Nhel, a monovalent cation/H(+)exchanger. The htt(-)-mutant also failed to orient correctly during natural aggregation, as was the case for the Nhel mutant. Moreover, in a K(+)-based buffer the normal localization of actin was similarly defective in both htt(-) and nhe1(-) cells in a K(+)-based buffer, and the normal localization of Nhe1 was disrupted in the htt(-) mutant. These observations demonstrate that Htt and Nhel play roles in the same specific cation-facilitated behaviors and that Nhel localization is directly or indirectly regulated by Htt. Similar cation-dependent behaviors and a similar relationship between Htt and Nhe1 have not been reported for mammalian neurons and deserves investigation, especially as it may relate to Huntington׳s disease. PMID:25149514

  17. Mechanism of Electrochemical Catalytic Treatment of Phenol Wastewater Catalyzed by Metal Ion Supported on Cation Exchange Resin%苯酚水在离子交换树脂电化学降解中的机理研究

    Institute of Scientific and Technical Information of China (English)

    王莹; 侯党社; 韩莉萍

    2011-01-01

    The electrochemical oxidation of phenol in synthetic wastewater catalyzed by metal ion supported on cation exchange resin has been investigated.It was found that in the process of the phenol oxidation, hydroxyl radicals and Fe were all attribute to the phenol oxidation.%本文以负载金属的离子交换树脂为催化剂,采用电化学降解的方法研究了苯酚水的降解机理.研究表明苯酚水在离子交换树脂电化学降解中可能是由羟基自由基、金属氧化物、金属离子、电絮凝等协同作用下进行降解.

  18. The development of sequential separation methods for the analysis of actinides in sediments and biological materials using anion-exchange resins and extraction chromatography

    International Nuclear Information System (INIS)

    New, quantitative methods for the determination of actinides have been developed for application to marine environmental samples (e.g., sediment and fish). The procedures include aggressive dissolution, separation by anion-exchange resin, separation and purification by extraction chromatography (e.g., TRU, TEVA and UTEVA resins) with measurement of the radionuclides by semiconductor alpha-spectrometry (SAS). Anion-exchange has proved to be a strong tool to treat large volume samples, and extraction chromatography shows an excellent selectivity and reduction of the amounts of acids. The results of the analysis of uranium, thorium, plutonium and americium isotopes by this method in marine samples (IAEA-384, -385 and -414) provided excellent agreement with the recommended values with good chemical recoveries. (author)

  19. Exchange bias associated with phase separation in the Nd2/3Ca1/3MnO3 manganite

    International Nuclear Information System (INIS)

    The exchange bias (EB) phenomenon has been found in Nd2/3Ca1/3MnO3 perovskite. The phenomenon manifests itself as a negative horizontal shift of magnetization hysteresis loops. The EB phenomenon is evident of an interface exchange coupling between coexisting antiferromagnetic (AFM) and ferromagnetic (FM) phases and confirms the phase separated state of the compound at low temperatures. The EB effect is found to be strongly dependent on the cooling magnetic field and the temperature, which is associated with the evolution of spontaneous AFM-FM phase separated state of the compound. Analysis of magnetic hysteresis loops has shown that ferromagnetic moment MFM originating from the FM clusters saturates in a relatively low magnetic field about H ∼ he obtained saturation value MFM (1 T) ∼ 0.45 μB is in a good agreement with our previous neutron diffraction data.

  20. A new type mixture refrigeration auto-cascade cycle with partial condensation and separation reflux exchanger and its preliminary experimental test

    Science.gov (United States)

    Wu, J. F.; Gong, M. Q.; Liu, J. L.; Luo, E. C.; Qi, Y. F.; Hu, Q. G.

    2002-05-01

    A new type of mixture refrigeration cycle with reflux exchanger is presented in this paper. In this cycle, a new type of L-V separator with inner heat and mass transfer is employed to replace the combination of conventional L-V separator or complicated rectifier and succeeding heat exchanger used in traditional auto-cascade cycle or Kleemenko cycle. A prototype is developed based on this refrigeration cycle. The thermodynamic performance is discussed as well as some other specifications such as cost, reliability, etc. The experimental results show that this prototype can reach 74 W at 135 K and 265 W at 171 K with a nominal input power of 1.5 HP.

  1. The separation and determination of trace elements in iron ore

    International Nuclear Information System (INIS)

    The separation, concentration, and determination of trace elements in iron ores are described. After the sample has been dissolved, the iron is separated by liquid-liquid extraction with a liquid cation-exchanger, di-(2-ethylhexyl) phosphoric acid. The trace elements aluminium, cadmium, calcium, chromium, cobalt, copper, lead, magnesium, manganese, mercury, potassium, sodium, vanadium, and zinc are determined in the aqueous phase by atomic-absorption spectrophotometry

  2. Design Features of the Separate Effect Test Facility for a Forced-Draft Sodium-to-Air Heat Exchanger (FHX) with Helical Finned Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungmo; Eoh, Jaehyuk; Ko, Yung Joo; Cho, Youngil; Kim, Jong-Man; Lee, Hyeong-Yeon; Jeong, Ji-Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    A sodium-cooled fast reactor (SFR) is one of the most promising options to pursue these purposes, and the Korea Atomic Energy Research Institute (KAERI) is currently developing a PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor) with a pool-type reactor vessel. Among the many components in an SFR, a decay heat removal system (DHRS) is very important for a safety of nuclear power plants. The PGSFR adopted two different kinds of DHRS: an active and passive DHRS, and the decay heat from the primary sodium pool is moved to the two kinds of sodium-to-air heat exchangers as ultimate heat sinks through sodium-to-sodium decay heat exchangers (DHX). To verify the cooling performances and thermal-hydraulic characteristics of this type of heat exchanger, a separate effect sodium test facility named as SELFA (Sodium thermal-hydraulic Experiment Loop for Finned-tube sodium-to-Air heat exchanger) is being developed. The purposes of SELFA are verification and validation of the design code for FHX. For this, scales and configurations of SELFA are carefully defined as similarity with the FHX in the PGSFR. In this paper, we propose the key design features of SELFA including the model FHX (M-FHX) unit. To verify and validate a design code of the FHX in PGSFR, a separate effect test facility called as SELFA has being developed in KAERI.

  3. Development of pillared M(IV) phosphate phosphonate inorganic organic hybrid ion exchange materials for applications in separations found in the nuclear fuel cycle

    Science.gov (United States)

    Burns, Jonathan David

    This dissertation focuses on key intergroup and intragroup separations found in the back end of the nuclear fuel cycle, specifically americium from lanthanides and americium from other actinides, most importantly americium from curium. Our goal is to implement a liquid-solid separation process to reduce waste and risk of contamination by the development of metal(IV) phosphate phosphonate inorganic organic hybrid ion exchange materials with the ideal formula of M(O6P2C6H4)0.5 (O3POA) ·nH2O, where M = Zr or Sn, A = H or Na. These materials have previously shown to have high affinity for Ln, this work will expand on the previous studies and provide methods for the above target separation, exploiting oxidation state and ion charge to drive the separation process. The optimum hydrothermal reaction conditions were determined by adjusting parameters such as reaction temperature and time, as well as the phosphonate to phosphate (pillar-to-spacer) ligands ratio. Following these results four bulk syntheses were performed and their ion exchange properties were thoroughly examined. Techniques such as inductively coupled mass spectrometry and liquid scintillation counting were used to determine the affinity of the materials towards Na+, Cs+, Ca2+, Sr 2+, Ni2+, Nd3+, Sm3+, Ho3+, Yb3+, NpO2+, Pu4+, PuO22+, Am3+, AmO2+, and Cm3+. Separation factors in the thousands have been observed for intergroup separations of the Ln from the alkali, alkaline earth, and low valent transition metals. A new method for Am oxidation was developed, which employed Na 2S2O8 as the oxidizing agent and Ca(OCl) 2 as the stabilizing agent for AmO2+ synthesis. Separation factors of 30-60 for Nd3+ and Eu3+ from AmO2+, as well as 20 for Cm3+ from AmO2+ were observed at pH 2. The work herein shows that a liquid-solid separation can be carried out for these difficult separations by means of oxidation and ion exchange.

  4. Ion exchange studies of alpha-hydroxy carboxylic acid-lanthanide and actinide systems

    International Nuclear Information System (INIS)

    Alpha-hydroxy carboxylic acids have been used extensively for the separation of lanthanide and actinide elements with cation exchange resins. Sorption of these elements in the same solutions occurs on strong base anion-exchange resins. A study has been made by elution and equilibrium distribution techniques of the behaviour at tracer-level concentrations of these anion-exchange systems. One objective was to measure the separation factors to assess anion exchange as a possible complement to cation exchange separation. Since very little attention has been given to characterizing the complexed species present in these separation systems, a second objective was to attempt such characterization through interpretation of both cation and anion exchange data. Glycolic, lactic and alpha-hydroxy isobutyric acids were used together with radioactive tracers of Ce, Pm, Eu, Tb, Tm, Y, Cm and Cf. The elutions and equilibrium distributions were performed both at 25o C and 87o C. In all three eluants, the separation factors were smaller for the anion exchange than for the analogous cation exchange. In the glycolate solutions, the separation factors were largest and the values of the distribution coefficient Kd. indicated that these were the most stable complexes. The plots of log Kd against log anion concentration pass through a maximum and then approach a slope of -1, indicating the presence of an anionic complex MX4-. The existence of this negative complex in the solution phase was demonstrated by electromigration studies of Tm170 tracer in these solutions. At the solution concentration corresponding to the maximum Kd value, it can be shown that the predominant solution species is MX3. Approximate successive stability constants have been calculated for these systems and with these it is possible to construct diagrams showing the relative concentration of the species M+3, MX+2, MX2+, MX3 and MX4- as a function of the concentration of X-. (author)

  5. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  6. Extremely slow cation exchange processes in Li4SiO4 probed directly by two-time 7Li stimulated-echo nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Lithium self-diffusion in the low-temperature modification of polycrystalline lithium ortho-silicate Li4SiO4 is investigated by 7Li two-time stimulated echo NMR spectroscopy. Extremely slow Li exchange processes were directly monitored between 300 and 433 K by recording spin-alignment echoes as a function of mixing time varying over six decades from 10-5 to 10 s. In the investigated temperature range the hopping correlation functions show biexponential behaviour. Whereas the first decay step reflects directly Li jumps between electrically different sites, the second one is simply induced by the decay of alignment order due to quadrupolar relaxation. The echo decay rates τ-1 (101 s-1≤τ-1≤104 s-1), which can be identified with Li jump rates, show Arrhenius behaviour with an activation energy of 0.53(1) eV. The directly measured jump rates are in good agreement with those obtained recently by one- and two-dimensional 6Li exchange MAS NMR reported in the literature

  7. Multidimensional separations of ubiquitin conformers in the gas phase: relating ion cross sections to H/D exchange measurements.

    Science.gov (United States)

    Robinson, Errol W; Williams, Evan R

    2005-09-01

    Investigating gas-phase structures of protein ions can lead to an improved understanding of intramolecular forces that play an important role in protein folding. Both hydrogen/deuterium (H/D) exchange and ion mobility spectrometry provide insight into the structures and stabilities of different gas-phase conformers, but how best to relate the results from these two methods has been hotly debated. Here, high-field asymmetric waveform ion mobility spectrometry (FAIMS) is combined with Fourier-transform ion cyclotron resonance mass spectrometry (FT/ICR MS) and is used to directly relate ubiquitin ion cross sections and H/D exchange extents. Multiple conformers can be identified using both methods. For the 9+ charge state of ubiquitin, two conformers (or unresolved populations of conformers) that have cross sections differing by 10% are resolved by FAIMS, but only one conformer is apparent using H/D exchange at short times. For the 12+ charge state, two conformers (or conformer populations) have cross sections differing by ion collisional cross sections and H/D exchange distributions are not strongly correlated and that factors other than surface accessibility appear to play a significant role in determining rates and extents of H/D exchange. Conformers that are not resolved by one method could be resolved by the other, indicating that these two methods are highly complementary and that more conformations can be resolved with this combination of methods than by either method alone.

  8. Speciation of selenoamino acids, selenonium ions and inorganic selenium by ion exchange HPLC with mass spectrometric detection and its application to yeast and algae

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Hansen, M.; Fan, T.;

    2001-01-01

    Cation and anion exchange HPLC were used to separate a mixture of 12 selenium species comprising selenoamino acids, selenonium ions and inorganic selenium. The cationic species were separated from each other and from the co-injected anions using a cation exchange column with gradient elution...... by aqueous pyridinium formate at pH similar to 3 as the mobile phase. The anionic species were separated using an anion exchange column with isocratic elution by an aqueous salicylate-TRIS mobile phase at pH 8.5. The separated selenium species were detected as Se-80 by ICP-dynamic reaction cell (DRC...... acid extract of Chlorella algae contained dimethylselenonium propionate (DMSeP), which was verified by HPLC-ES-MS. Se-allylselenocysteine and selenoethionine was detected at the low ng g(-1) concentration level based on co-chromatography with the standard substances spiked to the algal extract....

  9. Ion-exchange separation of nitrate from alkaline waste generated during preparation of UO3 microspheres by sol-gel process

    International Nuclear Information System (INIS)

    The paper describes the studies carried out for the separation of nitrate from hexamethylenetetramine (HMTA) and urea which are present in the alkaline waste generated during preparation of UO3 microspheres by sol-gel process. For separation, Dowex 1 X 4 was used as ion exchanger and 0.5 M NaOH was used as eluent. Experiments were conducted both under batch equilibration conditions as well as through column. The distribution ratio data for nitrate at different equilibrium concentration in solution phase were used to determine the capacity of the resin. The batch equilibration as well as column experiments showed that nitrate can be separated. The studies quantified the extent of nitrate removal from the waste and the amount of additional waste generated. (author)

  10. Industrial scale chromatographic separation of valuable compounds from biomass hydrolysates and side streams

    Energy Technology Data Exchange (ETDEWEB)

    Saari, P.

    2011-06-15

    Carbohydrates are composed of a number of various monosaccharides, glucose being the most abundant. Some of the monosaccharides are valuable compounds used in the food and pharmaceutical industries. They can be separated from biomass hydrolysates e.g. by chromatographic methods. In this thesis, chromatographic separation of valuable compounds using ion exchange resins was studied on an industrial scale. Of special interest were rare monosaccharides in biomass hydrolysates. A novel chromatographic separation process was developed for fucose, starting from pre-processed spent sulfite liquor. The core of the process consists of three chromatographic separations with different types of ion exchange resins. Chromatographic separation of galactose was tested with three biomass hydrolysates; lactose, gum arabic and hemicellulose hydrolysates. It was demonstrated that also galactose can be separated from complex carbohydrate mixtures. A recovery process for arabinose from citrus pectin liquid residual and for mannose from wood pulp hydrolysate were also developed and experimentally verified. In addition to monosaccharides, chromatographic separation of glycinebetaine from vinasse was examined with a hydrogen form weak acid cation exchange resin. The separation involves untypical peak formation depending, for example, on the pH and the cation composition. The retention mechanism was found to be hydrogen bonding between glycinebetaine and the resin. In the experimental part, all four resin types - strong acid cation, strong base anion, weak acid cation and weak base anion exchange resins - were used. In addition, adsorption equilibria data of seven monosaccharides and sucrose were measured with the resins in sodium and sulfate forms because such data have been lacking. It was found out that the isotherms of all sugars were linear under industrial conditions. A systematic method for conceptual process design and sequencing of chromatographic separation steps were developed

  11. Coordination chemistry of several radius-sensitive complexones and applications to lanthanide-actinide separations

    International Nuclear Information System (INIS)

    The relationships between the lanthanide complex formation equilibria and the lanthanide-actinide separation application of three radius sensitive ligands have been studied. The consecutive stepwise formation constants of the 1:1, 2:1, and 3:1 chelate species formed by the interaction of DHDMB and the tripositive lanthanides and yttrium were determined potentiometrically at 0.1 M ionic strength and 250C. Results indicate that three different coordination modes, one tridentate and two bidentate are in evidence. Tracer level 241Am - 155Eu cation-exchange experiments utilizing DHDMB eluents indicate that this dihydroxycarboxylate does not form a sufficiently strong americium complex to elute that actinide ahead of europium. The overall stability of the americium 3:1 complex appears intermediate between samarium and europium. Cation-exchange elutions of 241Am, 155Eu, and 160Tb mixtures with EEDTA solutions prove that the EEDTA ligand is capable of eluting americium ahead of all of the tripositive lanthanide cations. The minimum separation occurs with terbium, where the Am-Tb separation factor is 1.71. 1,5-diaminopentane-N,N,N',N'-tetraacetic acid (PMDTA) was synthesized using cation exchange. A mathematical method was developed for the formation constants of the protonated and unprotonated lanthanide-PMDTA complexes from potentiometry. Cation-exchange elutions of tracer quantities of Am, Eu, and Tb revealed that terbium is eluted ahead of both americium and europium

  12. Investigation on the Use of the Weakly Basic Polyacrylate Anion-Exchanger Amberlite IRA-68 for Sorption and Separation of Iminodiacetate Complexes of Rare Earth Elements

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the determined affinity series of rare earth element complexes with IMDA for the anion-exchangers, purification of macroquantities of Nd3+ from Y3+, Sm3+ from Ho3+, La3+ from Nd3+ and La3+ from Pr3+ on the weakly basic gel anion-exchanger Amberlite IRA-68 was studied. Using the presented method on 1 L of Amberlite IRA-68 in the acetate form, it is possible to obtain about 240 g Nd2O3 purified from Y2O3. Great difference in affinity of La3+ and Nd3+ as well as Pr3+ complexes for this anion-exchanger in the acetate form indicates the possibility of applying this process for purification of lanthanum on the increased scale. On 1 L of Amberilte IRA-68 in the acetate form it is possible to obtain about 1125 g La2O3 purified from Nd2O3. On the basis of these results it can be assumed that unique properties of polyacrylate anion-exchangers enable their application for separation of rare earth elements.

  13. Determination of Pt and Pd in particles emitted from automobile exhaust catalysts using ion-exchange matrix separation and voltammetric detection

    International Nuclear Information System (INIS)

    We report on the ion-exchange separation of Pt and Pd from the main elements emitted from catalysts of gasoline-fueled cars by exploiting the selective chelating ion exchanger Lewatit MonoPlus TP-214. Pt and Pd were then eluted with a recovery of 92% and 96%, respectively, using an acidified solution of thiourea, and the eluent was analyzed by sequential voltammetry. The detection limits are 0. 04 μg L-1 and 1 μg L-1 for Pt and Pd, respectively, and the relative standard deviation is about 4. 0% (for n = 10). The procedure was successfully applied to particles emitted from automobile exhaust catalysts of four capacity engine vehicles. Graphite furnace atomic absorption spectrometry was also employed for reasons of comparison. Emission by four vehicles with 1400, 2600, 3200, and 4800 cc engines, respectively, ranged from 19 to 28 ng km-1 for Pt, and from 102 to 150 ng km-1 for Pd. (author)

  14. Mercury(II) removal from aqueous solutions and wastewaters using a novel cation exchanger derived from coconut coir pith and its recovery

    International Nuclear Information System (INIS)

    A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R2 = 0.99; χ2 1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%

  15. Cationic Organic/Inorganic Hybrids and Their Swelling Properties

    Institute of Scientific and Technical Information of China (English)

    E. S. Dragan; L. Ghimici; M. Cazacu

    2005-01-01

    @@ 1Introduction Specific properties of poly(dimethylsiloxanes), such as low glass transition temperature, low surface energy, good insulating properties, biological and chemical inertness, high diffusion coefficient of gases, make them very attractive for practical applications in the daily life. However, there is a great interest last time in the preparation of ionic organic/inorganic materials with new properties for new applications. Quaternary ammonium salt(QAS) groups included in siloxane copolymers could induce new interesting properties such as:permanent fungicidal and bactericidal properties, which make them very attractive as materials for sanitary applications, improved selectivity coefficients of the gas-separation membranes, ion-exchange properties and so forth. So far, QAS groups have been located in the side chain[1,2]. Our interest was focused on the preparation of some novel cationic polysiloxane copolymers containing QAS groups of both integral type and pendent type[3,4]. Our objectives for the present study concern the synthesis of some cationic organic/siloxane hybrid materials with swelling properties controlled by both the nature of cationic organic component and the ratio between the organic and inorganic counterparts. Such cationic hybrid materials could be of interest for the preparation of new stimuli-responsive hydrogels[5,6].

  16. Electrically switched ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lilga, M.A. [Pacific Northwest National Lab., Richland, WA (United States); Schwartz, D.T.; Genders, D.

    1997-10-01

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

  17. Chiral ligand-exchange high-performance liquid chromatography with copper (II)-L-phenylalanine complexes for separation of 3,4-dimethoxy-α-methylphenylalanine racemes.

    Science.gov (United States)

    Jia, Dong-Xu; Ai, Zheng-Gui; Xue, Ya-Ping; Zheng, Yu-Guo

    2014-11-01

    L-3, 4-dimethoxy-α-methylphenylalanine (L-DMMD) is an important intermediate for the synthesis of 3-hydroxy-α-methyl-L-tyrosine (L-methyldopa). This paper describes an efficient, accurate, and low-priced method of high-performance liquid chromatography (HPLC) using chiral mobile phase and conventional C18 column to separate L-DMMD from its enantiomers. The effects of ligands, copper salts, organic modifiers, pHs of mobile phase, and temperatures on the retention factors (k') and selectivity (α) were evaluated to achieve optimal separation performance. Then, thermal analysis of the optimal separation conditions was investigated as well. It was confirmed that the optimal mobile phase was composed of 20 % (v/v) methanol, 8 mM L-phenylalanine (L-Phe), and 4 mM cupric sulfate in water of pH 3.2, and the column temperature was set at 20 °C. Baseline separation of two enantiomers could be obtained through the conventional C18 column with a resolution (R) of 3.18 in less than 18 min. Thermodynamic data (∆∆H and ∆∆S) obtained by Van't Hoff plots revealed the chiral separation was an enthalpy-controlled process. To the best of our knowledge, this is the first report regarding the enantioseparation of DMMD by chiral ligand-exchange HPLC.

  18. An Anion-Exchange Method for the Separation of P-32 Activity in Neutron-Irradiated Biological Material

    International Nuclear Information System (INIS)

    Strong hydrochloric-acid solutions containing small amounts of orthophosphoric and citric acid and radioactive tracers of the elements Na, P, K, Ca, Se, Cr, Mn, Ni, Rb, Sr, Cs, Ba, La, and Ce were titrated with a water suspension of strongly basic anion-exchange resin in the hydroxide form. The titration was carried out to pH = 3.0. It was followed by filtration of the mixture on the top of a small anion-exchange column in the chloride form and a final washing with water. Phosphorus was quantitatively adsorbed by the resin and the scandium retention was better than 96 per cent. The remaining elements passed quantitatively into the effluent, with the exception of nickel, which was adsorbed to a very small extent

  19. Profile Distribution of Exchangeable Cations under No-till and Conventional Tillage in An Aquic Brown Soil%免耕与常规耕作潮棕壤交换性阳离子的剖面分布特征

    Institute of Scientific and Technical Information of China (English)

    孙良杰; 张晓珂; 梁文举

    2009-01-01

    The effects of tillage systems on exchangeable cations of different layers to a 1 m depth in an aquic brown soil were studied in a field experiment. The results showed that no-tillage, compared with conventional tillage, significantly increased soil pH and reduced electronic conductivity (EC) in the 0- 5 cm layer. Soil exchangeable K~+ was improved in no-tillage treatment,while exchangeable Na was declined. However, there was no significant effect of tillage practices on soil exchangeable Ca~(2+) , Mg~(2+) and cation exchange capacity. Correlation analysis showed that no significant correlations were observed between exchangeable K and soil nutrients, whereas exchangeable Na~+ , Ca~(2+) , Mg~(2+) , as well as cation exchange capacity had significant negative correlations with organic matter (OM) and total nitrogen (TN), respectively.%通过田间定位试验.研究了不同耕作方式对潮棕壤0-100 cm深度6个土层土壤交换性阳离子的影响.结果表明,与常规耕作相比,免耕使土壤表层pH显著增,.而电导率下降;同时,免耕增加了表层土壤可交换性K~+含量,降低了可交换性Na~+含量,但对可交换性Ca~(2+),Mg~(2+)和阳离子交换量没有产生显著影响.相关分析结果表明,可交换性K~+与土壤养分含量没有显著相关性,而可交换性Na~+,Ca~(2+),Mg~(2+)和阳离子交换量与有机质和全氮含量均呈负相关关系.

  20. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    International Nuclear Information System (INIS)

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL−1, and demonstrated good linearity of R2 from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL−1. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified

  1. Heterodimers formed through a partial anionic exchange process: scanning tunneling spectroscopy to monitor bands across the junction vis-à-vis photoinduced charge separation

    Science.gov (United States)

    Bera, Abhijit; Saha, Sudip K.; Pal, Amlan J.

    2015-10-01

    We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk-heterojunction solar cells based on the nanostructures in a polymer matrix.We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk

  2. Physico-Chemical Study of the Separation of Calcium Isotopes by Chemical Exchange Between Amalgam and Salt Solutions; Etude physico-chimique de la separation des isotopes du calcium par echange chimique entre amalgame et solution saline

    Energy Technology Data Exchange (ETDEWEB)

    Duie, P.; Dirian, G. [Commissariat a l' Energie Atomique. Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1962-07-01

    In a preliminary study of the isotopic exchange between Ca amalgam and aqueous or organic solutions of Ca salts, the main parameters governing the feasibility of a separation process based on these systems such as separation factor, exchange kinetics, rate of decomposition of the amalgam were investigated. The separation factor between {sup 40}Ca and {sup 46}Ca was found to be of the order of 1.02. The rate of the exchange reaction is rather low for aqueous solutions, extremely low for organic solutions. The amalgam seems not to be attacked by dimethyl-formamide solutions; but it is rapidly decomposed by aqueous solutions of Ca halides. This decomposition is slow in the case of aqueous solutions of calcium formate and still slower for Ca(OH){sub 2}; however, except in particular conditions, the observed rate is often much higher, owing to interfering reactions between amalgam and water vapor contained in H{sub 2} bubbles. (authors) [French] On a fait une etude preliminaire, pour des systemes amalgame de calcium - solution aqueuse ou organique de sels de calcium, des principaux parametres pouvant intervenir dans l'application d'un procede d'echange a l'enrichissement isotopique du calcium: facteur de separation, cinetique de l'echange, cinetique de la decomposition de l'amalgame. Les facteurs de separation {sup 40}Ca-{sup 46}Ca sont de l'ordre de 1,02. L'echange est assez lent pour les solutions aqueuses, extremement lent pour les solutions organiques. La decomposition de l'amalgame est pratiquement inexistante avec les solutions dans le dimethyl- formamide, appreciable pour les solutions alcooliques, rapide pour les solutions aqueuses d'halogenures; elle est normalement lente pour les solutions aqueuses de formiate et surtout de chaux, mais la decomposition est en general acceleree par une reaction parasite entre l'amalgame et l'eau a l'etat vapeur, reaction que l'on n'evite dans des

  3. Non-ionic surfactant modified ligand exchange chromatography using copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive for enantioselective amino acids separation.

    Science.gov (United States)

    Dimitrova, Pepa; Bart, Hans-Jörg

    2010-03-17

    The influence of non-ionic surfactants on the selectivity and retention in the ligand exchange chromatography for the enantioselective separation of racemic mixtures of the amino acids dl-methionine, dl-leucine, dl-valine and dl-tyrosine applying chiral mobile phases was investigated, whereas five different surfactants were tested as modifiers. The experiments were carried out using a commercially available non-chiral RP-C8 column and the copper (II) complex of N,N-dimethyl-l-phenylalanine as the chiral additive. Varying the surfactant concentrations the retention factors and the selectivity could be controlled and in general no negative influence on the separation (due to surfactant adsorption on the non-chiral stationary phase) occurred. Changing the temperature the van't Hoff plots were obtained and the thermodynamic parameters calculated. Temperature had influence on the selectivity for each surfactant and lowered the retention times as expected.

  4. Lithium isotope separation by 6Li/7Li countercurrent exchange between lithium-amalgam and aqueous LiOH in a spray column

    International Nuclear Information System (INIS)

    Lithium isotope separation by 6Li/7Li exchange between lithium-amalgam and aqueous LiOH has been investigated by using a column consisting of a vertical Pyrex glass tube in which aqueous LiOH flows up and a fine spray of lithium-amalgam falls down. As the number of theoretical plates, a value of 48 was obtained on a single column while the amalgam stability was η = 0.74, where η is the ratio between Li concentration in amalgam at the column bottom and that at the column top. That is, a large separation may be obtained in a single column in spite of amalgam decomposition which takes place as a side reaction. (author)

  5. Properties of glass particles as ion exchangers and adsorbants: Separation of no-carrier-added mixtures of Pb and Bi radionuclides

    International Nuclear Information System (INIS)

    Separations of cyclotron produced 203Pb, 205Bi, and 206Bi and generator produced 212Pb and 212Bi radionuclides can be accomplished by pH dependent control of metal ion hydrolysis and selective binding to 0.5-2 μm sodium glass particles (Corning 0080). Much of the development of these separations represented a novel learning experience for neophyte (primarily undergraduate) radiochemical researchers. A candidate laboratory experiment was created to help students develop an appreciation for the properties of glass that cause it to act as an efficient ion exchanger or adsorbant for no-carrier-added (NCA) concentrations of radionuclides, frequently sub-picomolar; or conversely, be of little consequence in carrier-added (CA) situations

  6. Determination of traces of Pt and Rh in soil and quartz samples contaminated by automobile exhaust after an ion-exchange matrix separation.

    Science.gov (United States)

    Kowalska, Joanna; Kińska, Katarzyna; Pałdyna, Joanna; Czyżewska, Monika; Boder, Kamila; Krasnodębska-Ostręga, Beata

    2014-09-01

    Monitoring of PGEs content in the natural samples is a crucial point in the environment science since catalytic car converters have been introduced. In the presented paper application of a very sensitive voltammetric method for determination of traces of Pt and Rh in the environmental samples contaminated by automobile exhausts is discussed. Voltammetric measurements were carried out in the supporting electrolyte containing formaldehyde and semicarbazide. PGEs were separated from the digested solutions of soils or quartz samples, collected from monitoring plots-by applying an ion-exchange resin Cellex-T. Pt was very effectively separated from the matrix approaching nearly 100% recovery after its elution by hydrochloric acid. Moreover the conditions of soil and quartz samples digestion were discussed. To validate the obtained result an independent analytical method-ICP MS was applied and analysis of certified reference material road dust 723-was completed.

  7. Non-ionic surfactant modified ligand exchange chromatography using copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive for enantioselective amino acids separation

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrova, Pepa [TU Kaiserslautern, Institut fuer Thermische Verfahrenstechnik, P.O. Box 3049, Gottlieb-Daimler-Str. 44, 67653 Kaiserslautern (Germany); Bart, Hans-Joerg, E-mail: bart@mv.uni-kl.de [TU Kaiserslautern, Institut fuer Thermische Verfahrenstechnik, P.O. Box 3049, Gottlieb-Daimler-Str. 44, 67653 Kaiserslautern (Germany)

    2010-03-17

    The influence of non-ionic surfactants on the selectivity and retention in the ligand exchange chromatography for the enantioselective separation of racemic mixtures of the amino acids DL-methionine, DL-leucine, DL-valine and DL-tyrosine applying chiral mobile phases was investigated, whereas five different surfactants were tested as modifiers. The experiments were carried out using a commercially available non-chiral RP-C8 column and the copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive. Varying the surfactant concentrations the retention factors and the selectivity could be controlled and in general no negative influence on the separation (due to surfactant adsorption on the non-chiral stationary phase) occurred. Changing the temperature the van't Hoff plots were obtained and the thermodynamic parameters calculated. Temperature had influence on the selectivity for each surfactant and lowered the retention times as expected.

  8. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    Energy Technology Data Exchange (ETDEWEB)

    Beinhauer, Jana [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Bian, Liangqiao [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Fan, Hui [Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Šebela, Marek [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Kukula, Maciej [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Barrera, Jose A. [Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); and others

    2015-02-09

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL{sup −1}, and demonstrated good linearity of R{sup 2} from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL{sup −1}. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.

  9. Study of the separation of metallic compounds by means of an anion exchanger resin and of complexing media

    International Nuclear Information System (INIS)

    In order to define better separation conditions of molybdenum and aluminium from uranium alloys, this research thesis first reports the study of the fixation of each of these elements on a Dowex resin in a carbonate medium. Results obtained by other studies in a hydrogen carbonate medium has leaded to the use of mixing of CO32- and HCO3-. In a last part, the author reports the analysis of two samples (uranium-molybdenum and uranium-aluminium): after an attack of these alloys in a melt carbonate medium, components are separated by elution in one of the studied media

  10. Polymer coatings as separator layers for microbial fuel cell cathodes

    KAUST Repository

    Watson, Valerie J.

    2011-03-01

    Membrane separators reduce oxygen flux from the cathode into the anolyte in microbial fuel cells (MFCs), but water accumulation and pH gradients between the separator and cathode reduces performance. Air cathodes were spray-coated (water-facing side) with anion exchange, cation exchange, and neutral polymer coatings of different thicknesses to incorporate the separator into the cathode. The anion exchange polymer coating resulted in greater power density (1167 ± 135 mW m-2) than a cation exchange coating (439 ± 2 mW m-2). This power output was similar to that produced by a Nafion-coated cathode (1114 ± 174 mW m-2), and slightly lower than the uncoated cathode (1384 ± 82 mW m-2). Thicker coatings reduced oxygen diffusion into the electrolyte and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge transfer resistance and the highest oxygen reduction activity produced the most power in MFC tests. The results on hydrophilic cathode separator layers revealed a trade off between power and CE. Cathodes coated with a thin coating of anion exchange polymer show promise for controlling oxygen transfer while minimally affecting power production. © 2010 Elsevier B.V. All rights reserved.

  11. Preparation of quaternary amine monolithic column for strong anion-exchange chromatography and its application to the separation of Enterovirus 71.

    Science.gov (United States)

    Gu, Huimin; Yin, Dezhong; Ren, Jie; Zhang, Baoliang; Zhang, Qiuyu

    2016-10-15

    Large size virion is unable to diffuse into pores of conventional porous chromatography particles. Therefore, separation of virion by conventional column-packing materials is not quite efficient. To solve this problem, a monolithic column with large convective pores and quaternary amine groups was prepared and was applied to separate Enterovirus 71 (EV71, ≈5700-6000kDa). Cross-section, pore structure, hydrodynamic performance, adsorption property and dynamic binding capacity of prepared monolithic column were determined. Double-pore structures, macropore at 2472nm and mesopore at 5-60nm, were formed. The porosity was up to 63.3%, which enable higher permeability and lower back pressure of the monolithic column than commercial UNO™ Q1 column. Based on the breakthrough curves, the loading capacity of bovine serum albumin was calculated to be 42.0mg per column. In addition, prepared quaternary amine monolithic column was proved to be suitable for the separation of protein mixture by strong anion-exchange chromatography. As a practical application, prepared monolith column presents excellent performance to the separation of EV71 from virus-proteins mixture.

  12. Improvement of separation efficiencies of anion-exchange chromatography using monolithic silica capillary columns modified with polyacrylates and polymethacrylates containing tertiary amino or quaternary ammonium groups.

    Science.gov (United States)

    Watanabe, Yuta; Ikegami, Tohru; Horie, Kanta; Hara, Takeshi; Jaafar, Jafariah; Tanaka, Nobuo

    2009-10-30

    Anion-exchange (AEX) columns were prepared by on-column polymerization of acrylates and methacrylates containing tertiary amino or quaternary ammonium groups on monolithic silica in a fused silica capillary modified with anchor groups. The columns provided a plate height (H) of less than 10 microm at optimum linear velocity (u) with keeping their high permeability (K=9-12 x 10(-14) m2). Among seven kinds of AEX columns, a monolithic silica column modified with poly(2-hydroxy-3-(4-methylpiperazin-1-yl)propyl methacrylates) (HMPMA) showed larger retentions and better selectivities for nucleotides and inorganic anions than the others. The HMPMA column of 410 mm length produced 42,000-55,000 theoretical plates (N) at a linear velocity of 0.97 mm/s with a backpressure of 3.8 MPa. The same column could be employed for a fast separation of inorganic anions in 1.8 min at a linear velocity of 5.3 mm/s with a backpressure of 20 MPa. In terms of van Deemter plot and separation impedance, the HMPMA column showed higher performance than a conventional particle-packed AEX column. The HMPMA column showed good recovery of a protein, trypsin inhibitor, and it was applied to the separation of proteins and tryptic digest of bovine serum albumin (BSA) in a gradient elution, to provide better separation compared to a conventional particle-packed AEX column. PMID:19683243

  13. Lithium-sodium separation by ion-exchange. Particular study of a pulsed column; La separation lithium-sodium par echange d'ions. Etude particuliere d'une colonne a impulsions

    Energy Technology Data Exchange (ETDEWEB)

    Auvert, H. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-07-01

    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) [French] On se propose d'etudier les conditions et les servitudes de fonctionnement d'une colonne d'echangeurs d'ions a lit mobile, fonctionnant par 'impulsions'. L'exemple d'application choisi est la separation lithium-sodium en milieu hydroxyde (LiOH, NaOH). Dans une premiere partie, on etudie successivement les caracteristiques physico-chimiques de l'echange envisage et les caracteristiques cinetiques de la reaction d'echange mise en oeuvre. Dans une seconde partie on etudie le fonctionnement de la colonne a impulsions. A partir des resultats acquis dans la premiere partie, on determine les conditions necessaires a l'obtention d'un regime permanent. Lorsque celui-ci est atteint en colonne, les performances obtenues permettent de calculer la hauteur equivalente a un plateau theorique (HEPT) de l'installation. On etudie par ailleurs l'influence du 'glissement', phenomene inherent au fonctionnement de la colonne a impulsions. L

  14. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface.

    Science.gov (United States)

    Tsvetkov, Nikolai; Lu, Qiyang; Sun, Lixin; Crumlin, Ethan J; Yildiz, Bilge

    2016-09-01

    Segregation and phase separation of aliovalent dopants on perovskite oxide (ABO3) surfaces are detrimental to the performance of energy conversion systems such as solid oxide fuel/electrolysis cells and catalysts for thermochemical H2O and CO2 splitting. One key reason behind the instability of perovskite oxide surfaces is the electrostatic attraction of the negatively charged A-site dopants (for example, ) by the positively charged oxygen vacancies () enriched at the surface. Here we show that reducing the surface concentration improves the oxygen surface exchange kinetics and stability significantly, albeit contrary to the well-established understanding that surface oxygen vacancies facilitate reactions with O2 molecules. We take La0.8Sr0.2CoO3 (LSC) as a model perovskite oxide, and modify its surface with additive cations that are more and less reducible than Co on the B-site of LSC. By using ambient-pressure X-ray absorption and photoelectron spectroscopy, we proved that the dominant role of the less reducible cations is to suppress the enrichment and phase separation of Sr while reducing the concentration of and making the LSC more oxidized at its surface. Consequently, we found that these less reducible cations significantly improve stability, with up to 30 times faster oxygen exchange kinetics after 54 h in air at 530 °C achieved by Hf addition onto LSC. Finally, the results revealed a 'volcano' relation between the oxygen exchange kinetics and the oxygen vacancy formation enthalpy of the binary oxides of the additive cations. This volcano relation highlights the existence of an optimum surface oxygen vacancy concentration that balances the gain in oxygen exchange kinetics and the chemical stability loss. PMID:27295099

  15. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface

    Science.gov (United States)

    Tsvetkov, Nikolai; Lu, Qiyang; Sun, Lixin; Crumlin, Ethan J.; Yildiz, Bilge

    2016-09-01

    Segregation and phase separation of aliovalent dopants on perovskite oxide (ABO3) surfaces are detrimental to the performance of energy conversion systems such as solid oxide fuel/electrolysis cells and catalysts for thermochemical H2O and CO2 splitting. One key reason behind the instability of perovskite oxide surfaces is the electrostatic attraction of the negatively charged A-site dopants (for example, ) by the positively charged oxygen vacancies () enriched at the surface. Here we show that reducing the surface concentration improves the oxygen surface exchange kinetics and stability significantly, albeit contrary to the well-established understanding that surface oxygen vacancies facilitate reactions with O2 molecules. We take La0.8Sr0.2CoO3 (LSC) as a model perovskite oxide, and modify its surface with additive cations that are more and less reducible than Co on the B-site of LSC. By using ambient-pressure X-ray absorption and photoelectron spectroscopy, we proved that the dominant role of the less reducible cations is to suppress the enrichment and phase separation of Sr while reducing the concentration of and making the LSC more oxidized at its surface. Consequently, we found that these less reducible cations significantly improve stability, with up to 30 times faster oxygen exchange kinetics after 54 h in air at 530 °C achieved by Hf addition onto LSC. Finally, the results revealed a `volcano' relation between the oxygen exchange kinetics and the oxygen vacancy formation enthalpy of the binary oxides of the additive cations. This volcano relation highlights the existence of an optimum surface oxygen vacancy concentration that balances the gain in oxygen exchange kinetics and the chemical stability loss.

  16. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl-, NO3-, C2O42-) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author)

  17. Study on the permselectivity of ion exchange membrane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ion exchange membranes with high permselectivity (the character of separating cations from anions or anions from cations) and high selectivity (the character of separating cations or anions of different valencies) are important for electrodialysis process. The Donnan equilibrium theory, based on the equilibrium of ions and no electric field, can not exactly explain the permselectivity of ion exchange membrane for ED process, since it is impossible to set up a ion exchange equilibrium between membrane and solution and to neglect the influence of electrical driving force on ions during ED process. A novel model named "anti-electric potential " is established to interpret the permselectivity of ion exchange membrane, according to the determination of electric potential between membranes and the variation of elements content in solutions and membranes. The results of experiment prove that the "anti-electric potential" really exists within membranes. As for the selectivity, the results reveal that electric potential and hydration energy have great influence on the concentration and mobility of ions in membranes.

  18. Kilogram-scale purification of americium by ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Wheelwright, E. J.

    1979-01-01

    Sequential anion and cation exchange processes have been used for the final purification of /sup 241/Am recovered during the reprocessing of aged plutonium metallurgical scrap. Plutonium was removed by absorption of Dowex 1, X-3.5 (30 to 50 mesh) anion exchange resin from 6.5 to 7.5 M HNO/sub 3/ feed solution. Following a water dilution to 0.75 to 1.0 M HNO/sub 3/, americium was absorbed on Dowex 50W, X-8 (50 to 100 mesh) cation exchange resion. Final purification was accomplished by elution of the absorbed band down 3 to 4 successive beds of the same resin, preloaded with Zn/sup 2 +/, with an NH/sub 4/OH buffered chelating agent. The recovery of mixed /sup 241/Am-/sup 243/Am from power reactor reprocessing waste has been demonstrated. Solvent extraction was used to recover a HNO/sub 3/ solution of mixed lanthanides and actinides from waste generated by the reprocessng of 13.5 tons of Shippingport Power Reactor blanket fuel. Sequential cation exchange band-displacement processes were then used to separate americium and curium from the lanthanides and then to separate approx. 60 g of /sup 244/Cm from 1000 g of mixed /sup 241/Am-/sup 243/Am.

  19. 强酸性阳离子交换树脂催化合成乙酰水杨酸的研究%Synthesis of acetylsalicylic acid using strong-acidic cation-exchange resin as catalyst

    Institute of Scientific and Technical Information of China (English)

    赵志刚; 谢志融; 陈靠山

    2012-01-01

    目的:探讨001×7强酸性阳离子交换树脂催化合成乙酰水杨酸的方法和最佳工艺.方法:通过正交试验探讨了乙酸酐与水杨酸的摩尔比、反应时间、催化剂用量和反应温度对乙酰水杨酸产率的影响,并探讨催化剂的催化能力与使用次数的关系.结果:乙酸酐与水杨酸的摩尔比为3:1、催化剂用量为水杨酸质量的14.50%、反应时间120 min、反应温度60 ℃时,乙酰水杨酸产率最高,为77.93%.结论:001×7强酸性苯乙烯系阳离子交换树脂对酯化反应催化效果好,副反应少,对环境污染小,能重复使用,值得大力推广.%Objective:To optimize the technology of synthesizing acetylsalicylic acid using 001 × 7 strong-acidic cation-exchange resin as catalyst . Methods : Orthogonal experiment was performed to examine the effect of molar ratio of reactants,reaction time, dosage of catalyst, and reaction temperature on the yield of product as well as the efficiency and frequencies of the resin recycled and shifted on the synthesis. Results :The optimal reaction conditions were 3:1 (the ratio of acetic anhydride to salicylic acid,n:n),in a dosage of the resin 14. 50% of salicylic acid,for the reaction time of 120 min at temperature of 60 ℃ , which led to a yield of 77.93 % . Conclusion: 001 × 7 strong-acidic cat ion-exchange resin works well on esterification reaction as a environmentally friendly catalyst and is worthy of wider use, for it has efficient activity, less adverse reaction and recyclable advantages.

  20. Cationic ruthenium alkylidene catalysts bearing phosphine ligands

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2016-01-01

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bear-ing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions pro-vided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported...

  1. Liquid Anion Exchange Chromatographic Extraction and Separation of Platinum(IV with n-Octylaniline as a Metallurgical Reagent: Analysis of Real Samples

    Directory of Open Access Journals (Sweden)

    Ashwini P. Gaikwad

    2013-01-01

    Full Text Available A simple and selective method was developed for the determination of platinum(IV with n-octylaniline in toluene. In present study, the use of n-octylaniline in toluene for the extraction of platinum(IV from ascorbate media was carried out. The effect of various parameters, such as pH, equilibrium time, extractant concentration, and organic solvent on the extraction has been discussed. The back extraction of platinum(IV has been performed. On the basis of slope analysis, the composition of the extracted species was determined as [RR′NH2+ Pt(Succinate2−](org. The interfering effects of various cations and anions were also studied, and the selectivity of the method is enhanced by using suitable masking agents. The proposed method is rapid, reproducible and successfully applied for the determination of platinum(IV in binary and synthetic mixtures. The separation of pt(IV from other associated metals has been studied. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.

  2. A new digestion and chemical separation technique for rapid and highly reproducible determination of Lu/Hf and Hf isotope ratios in geological materials by mc-ICP-MS

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Baker, J.A.; Ulfbeck, D.

    2003-01-01

    metaborate. High field strength elements (HFSE) and rare earth elements (REE) are separated from this solution by co-precipitation with iron hydroxide. The dissolved precipitate (in 2 mol l HCl) is loaded directly onto a standard cation exchange column which separates remaining sample matrix from the heavy...

  3. Unconventional exchange bias effect driven by phase separation in basically antiferromagnetic Sm0.1Ca0.6Sr0.3MnO3

    International Nuclear Information System (INIS)

    Highlights: • Sm0.1Ca0.6Sr0.3MnO3 displays negative exchange bias (NEB) effect at low temperatures. • The NEB increases rapidly with increasing Hcool up to 100 Oe, but is almost Hcool independent at H > 0.5 kOe. • The sign of the EB changes with temperature from NEB at T < 40 K to a positive one at T ⩾ 40 K. • The atypical magnetic properties are related to two different interfaces appearing between coexisting magnetic phases. - Abstract: Magnetic investigations, focused on the uncommon behavior of the exchange bias (EB) effect, have been performed for basically antiferromagnetic (AFM) electron doped manganite Sm0.1Ca0.6Sr0.3MnO3. The studied system in the ground state exhibits a heterogeneous spin configuration consisting of the C-type antiferromagnetic phase with the Néel temperature TN-C ≈ 150 K, the G-type AFM phase with the Néel temperature TN-G ≈ 70 K, and a FM-like phase with very weak spontaneous magnetic moment. The phase separation, into two different AFM phases and a FM-like phase at the temperatures below TN-G, leads to unusual magnetic properties, such as: narrowing of magnetic hysteresis loops in field cooling process, unconventional EB effect associated with spontaneous magnetization at temperatures below TN-C, strong magnetic field dependence of the negative exchange bias at fields below 100 Oe turning into practically field independent one for fields above 0.5 kOe, significant shift of EB with temperature with a change of the sign from negative at 10 K to positive above 40 K. The atypical magnetic properties are discussed and related to two different interfaces appearing between coexisting magnetic phases

  4. Calculation Simulation of Mass Transfer Coefficient and Axial Effective Diffusivity of Uranium in The Separation of Uranium From Fission Products by Ion Exchange Method

    International Nuclear Information System (INIS)

    A mass transfer coefficient (kla) and an axial effective diffusivity (De) of U in the separation of U from fission products using ion exchange method have been calculated. In this separation process, mass transfer of uranium occurs in the liquid and solid phases. Mathematical model calculation is started by setting up mass balances on an element volume in the ion exchange column which can be assumed to have a similarity to the above process. The set up differential equations (in the form of simultaneous differential equations) are then solved using numerical analysis method. It is started by predicting the (kla) value to obtain the uranium concentrations as a function of distance and time, CA1(x,t) and XA1(x,t). Both the resulted concentrations of uranium and the predicted kla are used to calculate De and concentrations of uranium in the liquid, CA2(x,t) and solid phases, XA2(x,t). The resulted concentrations of uranium are then compared with the concentrations of uranium in the previous calculation. Both the kla and De values can be accepted if the difference between the concentrations resulted from both the calculations are similar or nearly equal, i.e the concentration difference performed by sum of squares of errors (SSE) is minimum (nearly zero). For the superficial linear velocity of about 20-40 cm/minute the results from the calculations are kl a= 15.18588 -20. 48588 per minute and De = 9.14117x10-4 - 1.11612x10-3 cm2/minute. The sum of squares of errors and the average relative error on the condition above are about 2.25117.10-9 - 3.98145x10-9 and 11,541% -25.981%

  5. Ion-exchange separation of radioiodine and its application to production of {sup 124}I by alpha particle induced reactions on antimony

    Energy Technology Data Exchange (ETDEWEB)

    Shuza Uddin, Md. [Forschungszentrum Juelich (Germany). Inst. fuer Neurowissenschaften und Medizin, INM-5: Nuklearchemie; Atomic Energy Research Establishment, Inst. of Nuclear Science and Technology, Dhaka (Bangladesh); Qaim, Seyed M.; Spahn, Ingo; Spellerberg, Stefan; Scholten, Bernhard; Coenen, Heinz H. [Forschungszentrum Juelich (Germany). Inst. fuer Neurowissenschaften und Medizin, INM-5: Nuklearchemie; Hermanne, Alex [Vrije Univ. Brussel (Belgium). Cyclotron Lab.; Hossain, Syed Mohammod [Atomic Energy Research Establishment, Inst. of Nuclear Science and Technology, Dhaka (Bangladesh)

    2015-07-01

    The basic parameters related to radiochemical separation of iodine from tellurium and antimony by anion-exchange chromatography using the resin Amberlyst A26 were studied. The separation yield of {sup 124}I amounted to 96% and the decontamination factor from {sup 121}Te and {sup 122}Sb was > 10{sup 4}. The method was applied to the production of {sup 124}I via the {sup 123}Sb(α, 3n) reaction. In an irradiation of 110 mg of {sup nat}Sb{sub 2}O{sub 3} (thickness ∝0.08 g/cm{sup 2}) with 38 MeV α-particles at 1.2 μA beam current for 4 h, corresponding to the beam energy range of E{sub α} = 37 → 27 MeV, the batch yield of {sup 124}I obtained was 12.42 MBq and the {sup 125}I and {sup 126}I impurities amounted to 3.8% and 0.7%, respectively. The experimental batch yield of {sup 124}I amounted to 80% of the theoretically calculated value but the level of the radionuclidic impurities were in agreement with the theoretical values. About 96% of the radioiodine was in the form of iodide and the inactive impurities (Te, Sb, Sn) were below the permissible level. Due to the relatively high level of radionuclidic impurity the {sup 124}I produced would possibly be useful only for restricted local consumption or for animal experiments.

  6. Process for strontium-82 separation

    International Nuclear Information System (INIS)

    A process for selective separation of strontium-82 and strontium-85 from proton irradiated molybdenum targets comprises dissolving the molybdenum target in a hydrogen peroxide solution to form a first solution containing ions selected from a group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium, rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, and yttrium; passing the solution through a first cationic resin whereby ions selected from a group consisting of zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium a portion of zirconium and a portion of rubidium are selectively absorbed by the first resin; contacting the first resin with an acid solution to strip and remove the absorbed ions from the first cationic exchange resin to form a second solution; evaporating the second solution for a time sufficient to remove substantially all of the acid and water from the solution whereby a residue remains; dissolving the residue in a dilute acid to form a third solution; passing the third solution through a second cationic resin whereby the ions are absorbed by the second resin; contacting the second resin with a dilute sulfuric acid solution whereby the absorbed ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium and zirconium are selectively removed from the second resin; and contacting the second resin with a dilute acid solution whereby the absorbed strontium ions are selectively removed. 1 fig

  7. Simultaneous separation and quantitative determination of monosaccharides, uronic acids, and aldonic acids by high performance anion-exchange chromatography coupled with pulsed amperometric detection in corn stover prehydrolysates

    Directory of Open Access Journals (Sweden)

    Xing Wang

    2012-11-01

    Full Text Available A method for simultaneous separation and quantitative determination of arabinose, galactose, glucose, xylose, xylonic acid, gluconic acid, galacturonic acid, and glucuronic acid was developed by using high performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD. The separation was performed on a CarboPacTM PA-10 column (250 mm × 2 mm with a various gradient elution of NaOH-NaOAc solution as the mobile phase. The calibration curves showed good linearity (R2 ≥ 0.9993 for the monosaccharides, uronic acids, and aldonic acids in the range of 0.1 to 12.5 mg/L. The detection limits (LODs and the quantification limits (LOQs were 4.91 to 18.75 μg/L and 16.36 to 62.50 μg/L, respectively. Relative standard deviations (RSDs of the retention times and peak areas for the seven consecutive determinations of an unknown amount of mixture were 0.15% to 0.44% and 0.22% to 2.31%, respectively. The established method was used to separate and determine four monosaccharides, two uronic acids, and two aldonic acids in the prehydrolysate from dilute acid steam-exploded corn stover within 21 min. The spiked recoveries of monosaccharides, uronic acids, and aldonic acids ranged from 91.25% to 108.81%, with RSDs (n=3 of 0.04% ~ 6.07%. This method was applied to evaluate the quantitative variation of sugar and sugar acid content in biomass prehydrolysates.

  8. New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

    Science.gov (United States)

    Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

    2015-03-20

    Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group.

  9. D296树脂吸附分离锆铪试验研究%Separation of Hafnium From Zirconium by D296 Ion-exchange Resin

    Institute of Scientific and Technical Information of China (English)

    刘小龙; 任萌; 李佳; 黎志万; 刘锦洪

    2015-01-01

    研究了用 D296树脂从硫酸体系中吸附锆、铪,考察了吸附时间、初始料液质量浓度、温度、硫酸浓度对树脂吸附锆、铪及锆、铪分离系数的影响及吸附反应动力学。结果表明:溶液中锆离子质量浓度为120 g/L 、温度1℃、硫酸浓度1.6 mol/L 条件下,D296树脂对锆、铪的静态吸附分离系数最大,为1.19。动力学研究结果表明,D296树脂吸附锆离子的控制步骤为液膜扩散,D296树脂吸附锆离子的活化能 E=158.639 kJ/mol 。%Adsorption separation of hafnium from zirconium in sulfuric acid medium by D 296 ion‐exchange resin was researched .The effects of adsorption time ,initial concentrate of zirconium and hafnium in solution ,temperature and sulfuric acid concentrate on separation coefficient of zirconium and hafnium were examined ,and the reaction dynamics was also studied .The results show that under the conditions of zirconium ion mass concentrate of 120 g/L ,temperature of 1 ℃ ,sulfuric acid concentrate of 1 .6 mol/L ,the static adsorption separation coefficient of zirconium and hafnium is maximum(1 .19) .Dynamics research results show that the main controlling step for D296 adsorption zirconium ion is liquid membrane diffusion .The adsorption activation energy of D296 for zirconium ion is 158 .639 kJ/mol .

  10. HPIC separation and quantification of Ca and Fe in uranium metal and alloy compounds

    International Nuclear Information System (INIS)

    The paper describes the separation and quantification of Ca and Fe from uranium metal and uranium based alloy fuels employing ion chromatography (IC). Ca separation from other metal ions of alkali and alkaline groups was carried out on a cation exchange column and the same was detected and quantified by means of conductivity detector. In case of Fe, it was separated from other transition elements using chelation ion chromatography where detection and quantification was carried out photometrically after the addition of PAR as post column reagent. For both the analyses a preliminary column chromatography separation for eliminating the bulk matrix uranium was performed. (author)

  11. Fractionation of whey proteins with high-capacity superparamagnetic ion-exchangers

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, Sune; Thomas, Owen R. T.

    2004-01-01

    was then contacted with the anion-exchanger. For both adsorbent classes of ion-exchanger, desorption selectivity was subsequently studied by sequentially increasing the concentration of NaCl in the elution buffer. In the initial cation-exchange step quantitative removal of lactoferrin (LF) and lactoperoxidase (LPO......) was achieved with some simultaneous binding of immunoglobulins (Ig). The immunoglobulins were separated from the other two proteins by desorbing with a low concentration of NaCl (=0.4 M), whereas lactoferrin and lactoperoxidase were co-eluted in significantly purer form, e.g. lactoperoxidase was purified 28...

  12. Separations chemistry

    International Nuclear Information System (INIS)

    Results of studies on the photochemistry of aqueous Pu solutions and the stability of iodine in liquid and gaseous CO2 are reported. Progress is reported in studies on: the preparation of macroporous bodies filled with oxides and sulfides to be used as adsorbents; the beneficiation of photographic wastes; the anion exchange adsorption of transition elements from thiosulfate solutions; advanced filtration applications of energy significance; high-resolution separations; and, the examination of the separation agents, octylphenylphosphoric acid (OPPA) and trihexyl phosphate (THP)

  13. Hidrólise parcial da superfície do polyethylene terephthalate (PET: transformando um rejeito em um material de troca catiônica para aplicação ambiental Partial hydrolysis of pet surface: transforming a plastic waste into a material with cationic exchange properties for environmental application

    Directory of Open Access Journals (Sweden)

    Marcelo G. Rosmaninho

    2009-01-01

    Full Text Available In this work it is proposed a simple and versatile undergraduate chemical experiment in polymer and environmental technology based on the process of polyethylene terephthalate (PET hydrolysis. Polyethylene terephthalate from post-consume bottles is submitted to a controlled partial hydrolysis which allows the students to follow the reaction by a simple procedure. The students can explore the reaction kinetics, the effect of catalysts and the exposed polyethylene terephthalate surface area on the hydrolysis reaction. The second and innovative part of this experiment is the technological and environmental application of the hydrolyzed polyethylene terephthalate as a material with cation exchange properties. The surface hydrolyzed polyethylene terephthalate can be used as adsorbent for cationic contaminants.

  14. Treatment of Spent ion-Exchange Resins from NPP by Supercritical Water Oxidation (SCWO) Process

    International Nuclear Information System (INIS)

    The spent cationic exchange resins and anionic exchange resins were separated from mixed spent exchange resins by a fluidized bed gravimetric separator. The separated resins were identified by an elemental analysis and thermogravimetric analysis. The each test sample was prepared by diluting the slurry made by wet ball milling the cationic exchange resins and the anionic exchange resins separated as a spherical granular form for 24 hours. The resulting test samples showed a slurry form of less than 75 μm of particle size and 25,000 ppm of CODcr. The decomposition conditions of each test samples from a thermal power plant were obtained with a lab-scale(reactor volume: 220 mL) supercritical water oxidation (SCWO) facility. Then pilot plant(reactor volume : 24 L) tests were performed with the test samples from a thermal power plant and a nuclear power plant successively. Based on the optimal decomposition conditions and the operation experiences by lab-scale facility and the pilot plant, a commercial plant(capacity: 150 kg/h) can be installed in a nuclear power plant was designed.

  15. Prediction of soil organic matter and cation exchange capacity based on spectral similarity measuring%基于相似光谱匹配预测土壤有机质和阳离子交换量

    Institute of Scientific and Technical Information of China (English)

    魏昌龙; 赵玉国; 李德成; 张甘霖; 邬登巍; 陈吉科

    2014-01-01

    The potential of visible-near infrared (vis-NIR, 350~2500nm) laboratory spectroscopy for the estimation of soil properties has been previously demonstrated in the literature. Spectroscopy is rapid, inexpensive, and non-destructive. A single spectrum allows for the simultaneous characterization of various soil properties. The question that always arises when two samples are close in spectral space is whether they are close in terms of soil composition. This paper explores three different approaches to improving prediction accuracy. The first, called the SAM Approach, predicts soil properties via similar soil spectra using a spectral angle mapper (SAM). The second one, called the PLSR Approach, predicts soil properties using partial least-squares regression (PLSR). The third, called the SAM-PLSR Approach, first uses the SAM to choose similar soil spectra, which are then used as calibration samples for the PLSR. These tests were performed on a collection of 400 soil samples from 91 profiles from the Xuancheng region of the Anhui Province. Spectra data include reflectance (R), first derivatives of reflectance (FDR), and the logarithm of the inverse of the reflectance (Log(1/R)). The aims of the work were threefold: (1) to investigate the relationship between soil vis-NIR similarity and soil attribute similarity (soil organic matter (SOM) and cation exchange capacity (CEC)) using a spectral angle mapper (SAM);(2) to predict soil properties by PLSR with different calibration samples, which were independently validated;(3) to compare the accuracy of predictions from the SAM Approach, PLSR Approach, and SAM-PLSR Approach. This study showed that soil vis-NIR similarity reflected the similarity of SOM and CEC content, the SAM Approach can be directly used to predict the content of SOM (R2=0.78, RPD=2.17) and CEC (R2=0.82, RPD=2.41). The PLSR Approach obtained good prediction accuracy of SOM (R2=0.87, RPD=2.77) and CEC (R2=0.87, RPD=2.59). The SAM-PLSR Approach, which was

  16. Chemical behavior of organic compounds in the interface ofwater/dual-cation organobentonite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The sorption behavior of polar or ionizable organiccompounds, such as p-nitrophenol, phenol and aniline, in thewater/organobentonite systems is investigated. Both adsorption andpartition occur to the sorption of organic compounds to dual-cationorganobentonites. The separate contributions of adsorption andpartition to the total sorption of organic compounds to dual-cationorganobentonites are analyzed mathematically in the first time. The factors to the contributions are also discussed. The results indicated that the contribution of adsorption and partition is related to the composition and ratio of dual-cation surfactants exchanging onto the bentonite. The sorption of organic compounds to dual-cation organobentonite is dominated by adsorption at low concentrations and by partition at high concentrations, making the organobentonites powerful sorbents for organic contaminants over wide range of concentrations.

  17. The separation of sulphur-35 and phosphorus-32 from urine and their subsequent estimation

    International Nuclear Information System (INIS)

    A method has been developed that will specifically separate sulphur-35 and phosphorus-32 from urine. Interfering cations are removed by cation exchange and differential precipitation is used to remove the unwanted anion(s). The anion of interest is estimated by liquid scintillation counting and recoveries are 95% for sulphur-35 and 70% for phosphorus-32. The detection limits for sulphur-35 and phosphorus-32 are estimated to be 1.5 pCi and 1.3 pCi, respectively (1 pCi = 37 mBq)

  18. 基于阳离子交换-反相混合分离模式的液相色谱-质谱联用检测河豚毒素新方法%Determination of tetrodotoxin using a cation exchange-reverse phase liquid chromatography-mass spectrometric method

    Institute of Scientific and Technical Information of China (English)

    刘希; 陈佳; 刘勤; 郭磊; 毛军文; 谢剑炜

    2012-01-01

    Objective To establish a highly sensitive method suitable for detection of intoxicated biomedical samples with regard to tetrodotoxin ,one of the most toxic non-proteins as well as a hydrophilic small biotoxin . Methods A novel method for detection of tetrodotoxin in human blood plasma by liquid chromatography -time of flight/mass spectrometry ( LC-TOF/MS) technique was established using a cation exchange -reverse phase separation mode. The LC-MS analysis and extraction conditions were systematically optimized. Results For the tetrodotoxin standard sample , the linear calibration curve ranged from 0.1 to 50 mg/L and the limit of detection ( LOD) was 0.01 mg/L. For the tetrodotoxin exposed human plasma sample, the linear calibration curve ranged from 0.5 to 10 mg/L and the LOD was 0.25 mg/L, respectively. Conclusion Such an LC-TOF/MS established for the detection of tetrodotoxin is highly specific and sensitive , and it can be feasible for the detection of tetrodotoxin at mg/L level in puffer fish biosamples.%目的 建立一种可用于检测中毒生物医学样品中小分子生物毒素--河豚毒素的高灵敏度分析方法.方法 选用阳离子交换-反相混合色谱柱,针对河豚毒素亲水性强的特点,建立了一种新型的液相色谱-飞行时间质谱方法对人血浆中河豚毒素进行检测,优化了液相色谱-质谱条件,考察了血浆中河豚毒素的提取方法.结果 对于参考品溶液,河豚毒素的线性范围为0.1~50 mg/L,检测限为0.01 mg/L;对于染毒人血浆样品,河豚毒素的线性范围为0.5~10 mg/L,检测限为0.25 mg/L.结论 所建立的液相色谱-飞行时间质谱方法专属性强、灵敏度高,可适用于实际测定河豚鱼头样品中 mg/L水平的河豚毒素.

  19. Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography.

    Science.gov (United States)

    Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim

    2016-04-01

    A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na(+)), potassium (K(+)), ammonium (NH4 (+)), chloride (Cl(-)) and nitrate (NO3 (-)) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples.

  20. Fractionation of whey proteins with high-capacity superparamagnetic ion-exchangers

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, S.F.L.; Thomas, Owen R. T.

    2004-01-01

    was then contacted with the anion-exchanger. For both adsorbent classes of ion-exchanger, desorption selectivity was subsequently studied by sequentially increasing the concentration of NaCl in the elution buffer. In the initial cation-exchange step quantitative removal of lactoferrin (LF) and lactoperoxidase (LPO......) was achieved with some simultaneous binding of immunoglobulins (1g). The immunoglobulins were separated from the other two proteins by desorbing with a low concentration of NaCl (less than or equal to0.4 M), whereas lactoferrin and lactoperoxidase were co-eluted in significantly purer form, e.......g. lactoperoxidase was purified 28-fold over the starting material, when the NaCl concentration was increased to 0.4-1 M. The anion-exchanger adsorbed beta-lactoglobulin (beta-LG) selectively allowing separation from the remaining protein....

  1. Evaluation of commercial resins for fructo-oligosaccharide separation.

    Science.gov (United States)

    Nobre, C; Suvarov, P; De Weireld, G

    2014-01-25

    Fructo-oligosaccharides (FOS) produced by fermentative processes are obtained in mixtures containing significant amounts of salts and other non-prebiotic sugars. A demineralisation process using a mixture of a cationic and an anionic resin was proposed. The separation of FOS from a mixture of fructose, glucose and sucrose was evaluated. Experiments were conducted with several commercial cationic exchange resins in calcium, sodium and potassium forms packed in preparative columns (7cm×2.2cm length×diameter). Resins in potassium form obtained the higher retention factor values for sugars when compared to the other ionic forms. However, when compared to calcium and sodium ones, resins in potassium cationic forms were shown to be the less efficient separating sugar mixtures. The resin with best separation performance was the Diaion UBK535Ca. A recovery yield of 92% (w/w) of FOS with 90% (w/w) of purity was obtained from batch experiments conducted in a single column loaded with the Diaion UBK535Ca resin at 25°C. The temperature shown did not influence the separation performance significantly. By increasing the column length, the purity of FOS increased to 92% (w/w), however the recovery yield decreased to 88% (w/w). PMID:23806732

  2. Simultaneous determination of NH4+, NO2- and NO3- by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent%Simultaneous determination of NH4+,NO2- and NO3- by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent

    Institute of Scientific and Technical Information of China (English)

    Masanobu MORI; Takahiro HIRONAGA; Hideyuki ITABASHI; Nobutake NAKATANI; Daisuke KOZAKI; Kazuhiko TANAKA

    2012-01-01

    Ion-exclusion/anion-exchange chromatography (IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH--form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion ( NH4+ ),nitrite ion (NO2-),and nitrate ion (NO3-) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity (TSKgel Super IC-Anion) showed well-resolved separation of cations and anions,In the optimization of the basic eluent,lithium hydroxide (LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH4+,NO2-,and NO3- ranged 1.28% - 3.57% and 0.54% - 1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH4+,1.87 μmol/L for NO2- and 2.83 μmol/L for NO3-.

  3. The separation of trace elements in manganese dioxide

    International Nuclear Information System (INIS)

    Separations from manganese are discribed for (a)Al(III), Mo(VI), V(V), and Ti(IV), and (b)trace elements in general. In the first separation, a combined anion-cation exchange, the oxalate complexes are absorbed onto the anionic BIO.RAD 1-X8 resin. V(V) and Al(III) are then eluted into a cation-exchange column from which they are eluted successively, Mo(VI) and Ti(IV) then being eluted from the anionic resin. In the second separation, up to 2g of manganese is absorbed onto BIO.RAD AG 50W-X8 resin, from which V(V) is eluted with dilute hydrochloric acid prior to the elution of Co(II), Cu(II), Zn(II), Cd(II), Fe(III), As(III), Sb(III), Mo(VI), W(VI), and Sn(II) with a mixture of 1 M hydrochloric acid, 80 per cent acetone, and 0,1 per cent hydrogen peroxide. Mn(11) is eluted next with a mixture of 0,75M hydrochloric acid and 90 per cent acetone, after which the remaining cations are eluted with 4M hydrochloric acid. Satisfactory recoveries ranging from 0,8 to 60 mg/l were obtained for 18 of the 21 elements tested. After concentration by evaporation, final measurements were made by the use of atomic-absorption spectrophotometry, or direct-reading spectrometry with excitation from an inductively coupled plasma source. Comparative results were obtained with atomic-absorption procedures where the manganese was not separated. However, the separation procedure can reduce the time required for analysis by the direct method because it limits the number of dilutions necessary and eliminates the need for the use of the method of additions to compensate for interferences from manganese

  4. Separation of opiate alkaloids by electrokinetic chromatography with sulfated-cyclodextrin as a pseudo-stationary phase.

    Science.gov (United States)

    Zakaria, Philip; Macka, Miroslav; Haddad, Paul R

    2003-01-24

    The separation of six related opiate alkaloids (morphine, thebaine, 10-hydroxythebaine, codeine, oripavine and laudanine) was studied using sulfated-cyclodextrin (s-CD) as a cation-exchange pseudo-stationary phase. Cation-exchange interactions between the cationic analytes and the anionic s-CD (7-11 mol of sulfate groups per mole CD) were found to bethe predominant mechanism, allowing the separations to be performed at low pH where the opiates are protonated and exhibit very similar mobilities. The concentrations of the s-CD and the competing ion (Na+ or Mg2+) in the electrolyte were used to govern the extent of the ion-exchange interactions. Interactions with the sulfated-cyclodextrin differed for each analyte, with oripavine exhibiting the strongest interaction and 10-thebaine and laudanine showing the weakest interactions. Despite the very similar structures of the analytes, these differences resulted in significant changes in separation selectivity. The separation was modelled using a migration equation derived from first principles and based on ion-exchange interactions between the s-CD and the opiates. Constants within the model were obtained by non-linear regression using a small subset of experimentally determined migration times. These constants related to the ion-exchange affinities of the s-CD for the various opiates. When the model was used to predict migration times under other experimental conditions, a very good correlation was obtained between observed and predicted mobilities (r2=0.996). Optimisation of the system was performed using the normalised resolution product and minimum resolution criteria and this process provided two optimised separations, each exhibiting a different separation selectivity.

  5. Research on Purification Process of Vindoline and Catharanthine from Catharanthus roseus by Means of Cation Exchange Resin%阳离子交换树脂纯化长春花中文多灵和长春质碱的工艺优选

    Institute of Scientific and Technical Information of China (English)

    柏道鸣; 周广涛; 代龙

    2012-01-01

    Objective: To select the optimum purifying process of Vindoline and Catharanthine from Catharanthus roseus by means of cation exchange resin. Method: The purifying process of Vindoline and Catharanthine from Catharanthus roseus was performed by cation exchange resin of LSD-001 type, with the solvent of ammonia water, the mixture of ammonia water and ethanol, acid water, the mixture of acid water and ethanol, the mixture of sodium chloride and ethanol, and the content of two alkaloids were determined to choose the optimal technological parameters. Result: The ideal concentration of solvent was: with 80% ethanol ( containing 1% sodium chloride ) eluent elution, two alkaloids eluting attained the highest rate. Conclusion : The purification process has well effect.It can be used for purifying Vindoline and Catharanthine from Catharanthus roseus by means of cation exchange resin.%目的:考察阳离子交换树脂不同洗脱溶剂纯化长春花中文多灵和长春质碱的效果,优选最佳工艺条件.方法:采用LSD-001大孔型阳离子交换树脂对长春花中文多灵和长春质碱进行纯化,以两种生物碱含量为指标,考察以氨水、氨性乙醇、酸水、酸性乙醇、盐醇为洗脱剂纯化两种生物碱的效果.结果:经过优选,离子交换树脂的最佳洗脱条件为:以80%乙醇(含1%氯化钠)洗脱剂洗脱时,两种生物碱的洗脱率最高.结论:优选得到的工艺纯化长春花中文多灵和长春质碱效果好,节省溶剂,工艺简单,可用于长春花中两种生物碱的分离纯化.

  6. Separation and recovery of sodium nitrate from low-level radioactive liquid waste by electrodialysis

    International Nuclear Information System (INIS)

    An advanced method, in which electrodialysis separation of sodium nitrate and decomposition of nitrate ion are combined, has been developed to remove nitrate ion from low-level radioactive liquid wastes including nitrate salts of high concentration. In the electrodialysis separation, the sodium nitrate was recovered as nitric acid and sodium hydroxide. When they are reused, it is necessary to reduce the quantity of impurities getting mixed with them from the waste fluid as much as possible. In this study, therefore, a cation exchange membrane with permselectivity for sodium ion and an anion exchange membrane with permselectivity for monovalent anion were employed. Using these membranes sodium and nitrate ions were effectively removed form a sodium nitrate solution of high concentration. And also it was confirmed that sodium ion was successfully separated from cesium and strontium ions and that nitrate ion was separated from sulfate and phosphate ions. (author)

  7. Ion Exchange and Thin Layer Chromatographic Separation and Identification of Amino Acids in a Mixture: An Experiment for General Chemistry and Biotechnology Laboratories

    Science.gov (United States)

    Brunauer, Linda S.; Caslavka, Katelyn E.; Van Groningen, Karinne

    2014-01-01

    A multiday laboratory exercise is described that is suitable for first-year undergraduate chemistry, biochemistry, or biotechnology students. Students gain experience in performing chromatographic separations of biomolecules, in both a column and thin layer chromatography (TLC) format. Students chromatographically separate amino acids (AA) in an…

  8. Separation of traces of metal ions from sodium matrices

    Science.gov (United States)

    Korkisch, J.; Orlandini, K. A.

    1969-01-01

    Method for isolating metal ion traces from sodium matrices consists of two extractions and an ion exchange step. Extraction is accomplished by using 2-thenoyltrifluoracetone and dithizone followed by cation exchange.

  9. Water quality monitoring system for determination of ionic nutrients by ion-exclusion chromatography with spectrophotometric detection on cationand anion-exchange resin columns using water eluent

    Institute of Scientific and Technical Information of China (English)

    Daisuke KOZAKI; Nobutakc NAKATANI; Masanobu MORI; Nobukazu NAKAGOSHI; Kazuhiko TANAKA

    2012-01-01

    A unified ion-exclusion chromatography(IEC)system for monitoring anionic and cationic nutrients like NH+4,NO-2,NO-3,phosphate ion,silicate ion and HCO-3 was developed and applied to several environmental waters.The IEC system consisted of four IEC methodologies,including the IEC with ultraviolet(UV)detection at 210 nm for determining NH-4 on anion-exchange separation column in OH form connected with anion-exchange UV-conversion column in I-form in tandem,the IEC with UV-detection at 210 nm for determining simultaneously NO-2 and NO-3 on cation-exchange separation column in H+ form,the IEC with UV-detection at 210 nm for determining HCO-3 on cation-exchange separation column in H+ form connected with anionexchange UV-conversion column in I-form in tandem,and the IEC with visible-detection based on molybdenum-blue reaction for determining simultaneously silicate and phosphate ions on cation-exchange separation column in H + form.These IEC systems were combined through three manually-driven 6-port column selection valves to select each separation column to determine selectively the ionic nutrients.Using this sequential water quality monitoring system,the analytical performances such as calibration linearity,reproducibility,detection limit and recovery were also tested under the optimized chromatographic conditions.This novel water quality monitoring system has been applied successfully for the determination of the ionic eutrophication components in sub-urban river waters.

  10. Avaliação da capacidade de troca de cátions em solos utilizando o método do tampão SMP Evaluation of the cation exchange capacity of soils utilizing the SMP buffer method

    Directory of Open Access Journals (Sweden)

    Otávio Antonio de Camargo

    1982-01-01

    Full Text Available Foram feitas as determinações da capacidade de troca de cations (CTC em amostras de solos pelos métodos do acetato de cálcio IN pH 7,0; acetato de amônio IN pH 7,0, e cloreto de bário tamponado com trietanolamina pH 8,2, sendo os resultados comparados com os obtidos utilizando o método do tampão SMP para determinar (H + Al mais a soma de bases, rotineiramente obtida em laboratório. As correlações entre os resultados de (H + Al, CTC e porcentagens de saturação em bases obtidas pelos diferentes métodos e pelo tampão SMP foram altas. Em vista disso e das vantagens operacionais que apresenta, o método do tampão SMP mostrou-se adequado para a avaliação da capacidade de troca de cations em determinações de rotina.The cation exchange capacity (CEO of soil determined by the methods of IN calcium acetate at pH 7.0, IN amonium acetate at pH 7.0 and triethanolamine buffered barium chloride at pH 8.2 were compared with results obtained by the SMP buffer method to determine (H + Al added to the sum of bases to calculate the CEC. The correlations between the results, obtained by the different methods, of (H + Al, CEC, and percent base saturation and the SMP were high. Due to this fact and the operational advantages, the SMP method showed to be adequate for CEC determination in routine analysis.

  11. Mechanisms of flotation separation of diaspore and kaolinite by quaternary ammonium salt DTAL

    Institute of Scientific and Technical Information of China (English)

    陈湘清; 胡岳华; 王毓华

    2004-01-01

    The FTIR spectroscopy indicates that the adsorption of quaternary ammonium salt DTAL on the diaspore and kaolinite is physical adsorption. The adsorption of cationic surfactants measured by two-phase titration shows that the adsorption on the kaolinite is notably more than that on diaspore. The adsorption isotherm on kaolinte is linear while that of DTAL on diaspore is two-step flat form. The analysis on the cationic ions of kaolinite supernatants shows that kaolinite releases plenty of crystalloid structure ions which countervail the crystalloid charge because of the adsorption of the cationic surfactant. The mechanisms of the quaternary ammonium salt DTAL on flotation separation of diaspore and kaolinite include ion exchange interaction as well as electrostatic force.

  12. 银离子交换树脂π-络合吸附分离乙烯乙烷的研究%Study of Adsorptive Ethylene/Ethane Separation with Ag+-Exchanged Resins via π-Complexation

    Institute of Scientific and Technical Information of China (English)

    吴忠标; 刘越

    2002-01-01

    Ag+-exchanged resins are prepared and studied for ethylene/ethane separation by adsorption. OnAg+-exchanged S9, at 25℃ and 0.1013 MPa, the equilibrium adsorbed amount for C2H4 is 0.992 mmol.g-1, andthe adsorption ratio for C2H4/C2H6 is 3.56. The adsorption capacity can be restored almost completely at 25℃and 75℃, and the desorption residual amount is less than 0.01 mmol.g-1. For the adsorption consisting of physicaladsorption and π-complexation with energy heterogeneity, the equilibrium data are correlated with Langmuir-Freundlich isotherm equation. Furthermore, the heat of adsorption and the overall diffusion time constants arecalculated from the experimental data. Considering all the adsorption characteristics, the application potential forindustrial adsorption process is discussed.

  13. Cation exchange for mercury and cadmium of xanthated, sulfonated, activated and non-treated subbituminous coal, commercial activated carbon and commercial synthetic resin:effect of pre-oxidation on xanthation of subbituminous coal

    Institute of Scientific and Technical Information of China (English)

    Lewis M. Gomez; Fredy Colpas-Castillo; Roberto Fernandez-Maestre

    2014-01-01

    A subbituminous coal was oxidized with air at 150 ?C on a fixed bed for 4 h and xanthated with carbon disulfide in a basic solution, at 30 or 5–10 ?C. This xanthated coal was evaluated for the removal of Hg2? and Cd2? from 7,000 mg/L aqueous solutions; metal concentrations were determined by atomic absorption spectrometry. The ion exchange of the xanthated coal was compared against those of the original subbituminous coal, a sulfonated subbituminous coal, activated carbon, commercial activated carbon, and commercial synthetic resin. The commercial synthetic resin showed the highest exchange capacity (concentration factor 98%) followed by the xanthated coal (concentration factor 96%). The retention of cadmium on the sulfonated subbituminous coal was lower (exchange capacity 0.56 meq/g) than that of xanthated coals (1.85 ± 0.09 meq/g). Our xanthated coal showed a better Cd2? removal (81%against 15%) than a non preoxidized 40-h-xanthated coal, which shows that oxidation of coal increased the amount of oxygenated groups which enhanced xanthation.

  14. An investigation of the applicability of the new ion exchange resin, Reillex{trademark}-HPQ, in ATW separations. Milestone 4, Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ashley, K.R.; Ball, J.; Grissom, M.; Williamson, M.; Cobb, S.; Young, D.; Wu, Yen-Yuan J.

    1993-09-07

    The investigations with the anion exchange resin Reillex{trademark}-HPQ is continuing along several different paths. The topics of current investigations that are reported here are: The sorption behavior of chromium(VI) on Reillex{trademark}-HPQ from nitric acid solutions and from sodium hydroxide/sodium nitrate solutions; sorption behavior of F{sup {minus}} on Reillex{trademark}-HPQ resin in acidic sodium nitrate solution; sorption behavior of Cl{sup {minus}} on Reillex{trademark}-HPQ resin in acidic sodium nitrate solution; sorption behavior of Br{sup {minus}} on Reillex{trademark}-HPQ resin in acidic sodium nitrate solution; and the Honors thesis by one of the students is attached as Appendix II (on ion exchange properties of a new macroperous resin using bromide as the model ion in aqueous nitrate solutions).

  15. Effects of pressure, temperature and atomic exchanges on phase separation dynamics in Au/Ni(111) surface alloy: Kinetic Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Zvejnieks, G. [Institute for Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Ibenskas, A., E-mail: ibenskas@pfi.lt [Center for Physical Sciences and Technology, Semiconductor Physics Institute, Gostauto 11, LT-01108 Vilnius (Lithuania); Tornau, E.E. [Center for Physical Sciences and Technology, Semiconductor Physics Institute, Gostauto 11, LT-01108 Vilnius (Lithuania)

    2015-11-15

    Instability of the Au/Ni(111) surface alloy is studied in different CO gas pressure, p, and temperature limits using kinetic Monte Carlo simulations. We analyze the reaction front dynamics and formation of Au clusters using the model which takes into account surface adatom pair and three-body interactions, CO adsorption and desorption, catalytic carbonyl formation reaction, Au and Ni adatom diffusion and their concerted exchange. Variation of interaction parameters allows us to identify three possible reaction front propagation limits with different pressure dependencies: (i) slow channel-like flow in agreement with experimental data [1] (step flow rate, R, increases with p), (ii) intermediate regime (weak p–dependence), and (iii) fast homogeneous flow (R decreases with p). We find that only Au–Ni exchange, contrary to both Ni–CO and Au–CO exchanges, significantly reduces the number of screened Ni atoms inside the Au clusters and stimulates the occurrence of Ni-free Au clusters. The size of Au islands depends on both pressure and temperature. At a fixed temperature it decreases with pressure due to an increased step flow rate. In the high temperature limit, despite the step flow rate exponential increase with temperature, the cluster size increases due to an enhanced Au mobility. - Highlights: • Kinetic Monte Carlo study of Au–Ni surface alloy instability to CO pressure and temperature. • Three reaction front propagation regimes. • In channel-like regime, the step flow rate increases with CO pressure as in experiment. • Ni-free Au islands are obtained when Au-Ni adatom exchange mechanism is considered. • The size of Au islands decreases with pressure and increases with temperature.

  16. Effects of pressure, temperature and atomic exchanges on phase separation dynamics in Au/Ni(111) surface alloy: Kinetic Monte Carlo study

    International Nuclear Information System (INIS)

    Instability of the Au/Ni(111) surface alloy is studied in different CO gas pressure, p, and temperature limits using kinetic Monte Carlo simulations. We analyze the reaction front dynamics and formation of Au clusters using the model which takes into account surface adatom pair and three-body interactions, CO adsorption and desorption, catalytic carbonyl formation reaction, Au and Ni adatom diffusion and their concerted exchange. Variation of interaction parameters allows us to identify three possible reaction front propagation limits with different pressure dependencies: (i) slow channel-like flow in agreement with experimental data [1] (step flow rate, R, increases with p), (ii) intermediate regime (weak p–dependence), and (iii) fast homogeneous flow (R decreases with p). We find that only Au–Ni exchange, contrary to both Ni–CO and Au–CO exchanges, significantly reduces the number of screened Ni atoms inside the Au clusters and stimulates the occurrence of Ni-free Au clusters. The size of Au islands depends on both pressure and temperature. At a fixed temperature it decreases with pressure due to an increased step flow rate. In the high temperature limit, despite the step flow rate exponential increase with temperature, the cluster size increases due to an enhanced Au mobility. - Highlights: • Kinetic Monte Carlo study of Au–Ni surface alloy instability to CO pressure and temperature. • Three reaction front propagation regimes. • In channel-like regime, the step flow rate increases with CO pressure as in experiment. • Ni-free Au islands are obtained when Au-Ni adatom exchange mechanism is considered. • The size of Au islands decreases with pressure and increases with temperature

  17. First principles molecular dynamics simulation of a task-specific ionic liquid based on silver-olefin complex: atomistic insight into separation process

    CERN Document Server

    Jiang, De-en

    2008-01-01

    First principles molecular dynamics based on density functional theory is applied to a hypothetical ionic liquid whose cations and anions are silver-ethylene complex [Ag(C2H4)2+] and tetrafluoroborate [BF4-], respectively. This ionic liquid represents a group of task-specific silver complex-based ionic liquids synthesized recently. Molecular dynamics simulations at two temperatures are performed for five picoseconds. Events of association, dissociation, exchange, and recombination of ethylene with silver cation are observed. A mechanism of ethylene transfer similar to the Grotthus type of proton transfer in water is identified, where a silver cation accepts one ethylene molecule and donates another to a neighboring silver cation. This mechanism may contribute to fast transport of olefins through ionic liquid membranes based on silver complexes for olefin/paraffin separation.

  18. First principles molecular dynamics simulation of a task-specific ionic liquid based on silver-olefin complex: atomistic insights into a separation process.

    Science.gov (United States)

    Jiang, De-en; Dai, Sheng

    2008-08-21

    First principles molecular dynamics based on density functional theory is applied to a hypothetical ionic liquid whose cations and anions are silver-ethylene complex [Ag(C2H4)2+] and tetrafluoroborate [BF4-], respectively. This ionic liquid represents a group of task-specific silver complex-based ionic liquids synthesized recently. Molecular dynamics simulations at two temperatures are performed for five picoseconds. Events of association, dissociation, exchange, and recombination of ethylene with silver cation are found. A mechanism of ethylene transfer similar to the Grotthus type of proton transfer in water is identified, where a silver cation accepts one ethylene molecule and donates another to a neighboring silver cation. This mechanism may contribute to fast transport of olefins through ionic liquid membranes based on silver complexes for olefin/paraffin separation.

  19. Role of extracellular cations in cell motility, polarity, and chemotaxis

    Directory of Open Access Journals (Sweden)

    Soll D

    2011-04-01

    Full Text Available David R Soll1, Deborah Wessels1, Daniel F Lusche1, Spencer Kuhl1, Amanda Scherer1, Shawna Grimm1,21Monoclonal Antibody Research Institute, Developmental Studies, Hybridoma Bank, Department of Biology, University of Iowa, Iowa City; 2Mercy Medical Center, Surgical Residency Program, Des Moines, Iowa, USAAbstract: The concentration of cations in the aqueous environment of free living organisms and cells within the human body influence motility, shape, and chemotaxis. The role of extracellular cations is usually perceived to be the source for intracellular cations in the process of homeostasis. The role of surface molecules that interact with extracellular cations is believed to be that of channels, transporters, and exchangers. However, the role of Ca2+ as a signal and chemoattractant and the discovery of the Ca2+ receptor have demonstrated that extracellular cations can function as signals at the cell surface, and the plasma membrane molecules they interact with can function as bona fide receptors that activate coupled signal transduction pathways, associated molecules in the plasma membrane, or the cytoskeleton. With this perspective in mind, we have reviewed the cationic composition of aqueous environments of free living cells and cells that move in multicellular organisms, most notably humans, the range of molecules interacting with cations at the cell surface, the concept of a cell surface cation receptor, and the roles extracellular cations and plasma membrane proteins that interact with them play in the regulation of motility, shape, and chemotaxis. Hopefully, the perspective of this review will increase awareness of the roles extracellular cations play and the possibility that many of the plasma membrane proteins that interact with them could also play roles as receptors.Keywords: extracellular cations, chemotaxis, transporters, calcium, receptors

  20. Zebrafish ("Danio rerio") endomembrane antiporter similar to a yeast cation/H(+) transporter is required for neural crest development

    Science.gov (United States)

    CAtion/H (+) eXchangers (CAXs) are integral membrane proteins that transport Ca (2+) or other cations by exchange with protons. While several yeast and plant CAX proteins have been characterized, no functional analysis of a vertebrate CAX homologue has yet been reported. In this study, we further ch...

  1. Alkaline earth cation extraction from acid solution

    Science.gov (United States)

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

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

    Science.gov (United States)

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

    2016-05-01

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

  3. Accelerated Analyte Uptake on Single Beads in Microliter-scale Batch Separations using Acoustic Streaming: Plutonium Uptake by Anion Exchange for Analysis by Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, Walter F.; O' Hara, Matthew J.; Peper, Shane M.; Petersen, Steven L.; Grate, Jay W.

    2008-06-01

    The use of acoustic streaming as a non-contact mixing platform to accelerate mass transport-limited diffusion processes in small volume heterogeneous reactions has been investigated. Single bead anion exchange of plutonium at nanomolar and sub-picomolar concentrations in 20 microliter liquid volumes was used to demonstrate the effect of acoustic mixing. Pu uptake rates on individual ~760 micrometer diameter AG 1x4 anion exchange resin beads were determined using acoustic mixing and compared with Pu uptake rates achieved by static diffusion alone. An 82 MHz surface acoustic wave (SAW) device was placed in contact with the underside of a 384-well microplate containing flat-bottomed semiconical wells. Acoustic energy was coupled into the solution in the well, inducing acoustic streaming. Pu uptake rates were determined by the plutonium remaining in solution after specific elapsed time intervals, using liquid scintillation counting (LSC) for nanomolar concentrations and thermal ionization mass spectrometry (TIMS) analysis for the sub-picomolar concentration experiments. It was found that this small batch uptake reaction could be accelerated by a factor of about five-fold or more, depending on the acoustic power applied.

  4. Evaluation of glycidyl methacrylate-based monolith functionalized with weak anion exchange moiety inside 0.5 mm i.d. column for liquid chromatographic separation of DNA

    Directory of Open Access Journals (Sweden)

    Aprilia Nur Tasfiyati

    2016-03-01

    Full Text Available In this study, the organic polymer monolith was developed as a weak anion exchanger column in high performance liquid chromatography for DNA separation. Methacrylate-based monolithic column was prepared in microbore silicosteel column (100 × 0.5 mm i.d. by in-situ polymerization reaction using glycidyl methacrylate as monomer; ethylene dimethacrylate as crosslinker; 1-propanol, 1,4-butanediol, and water as porogenic solvents, with the presence of initiator α,α′-azobisisobutyronitrile (AIBN. The monolith matrix was modified with diethylamine to create weak anion exchanger via ring opening reaction of epoxy groups. The morphology of the monolithic column was studied by SEM. The properties of the monolithic column, such as permeability, mechanical stability, binding capacity and pore size distribution, were characterized in detail. From the results of the characterization, monoliths poly-(GMA-co-EDMA with total monomer percentage (%T 40 and crosslinker percentage (%C 25 was found to be the ideal composition of monomer and crosslinker. It has good mechanical stability and high permeability, adequate molecular recognition sites (represented with binding capacity value of 36 mg ml−1, and has relatively equal proportion of flow-through pore and mesopores (37.2% and 41.1% respectively. Poly-(GMA-co-EDMA with %T 40 and %C 25 can successfully separate oligo(dT12–18 and 50 bp DNA ladder with good resolution.

  5. Analytical-scale separations of lanthanides : a review of techniques and fundamentals.

    Energy Technology Data Exchange (ETDEWEB)

    Nash, K. L.; Jensen, M. P.

    1999-10-27

    Separations chemistry is at the heart of most analytical procedures to determine the rare earth content of both man-made and naturally occurring materials. Such procedures are widely used in mineral exploration, fundamental geology and geochemistry, material science, and in the nuclear industry. Chromatographic methods that rely on aqueous solutions containing complexing agents sensitive to the lanthanide cationic radius and cation-exchange phase transfer reactions (using a variety of different solid media) have enjoyed the greatest success for these procedures. In this report, they will briefly summarize the most important methods for completing such analyses. they consider in some detail the basic aqueous (and two-phase) solution chemistry that accounts for separations that work well and offer explanations for why others are less successful.

  6. Analytical-scale separations of lanthanides : a review of techniques and fundamentals

    International Nuclear Information System (INIS)

    Separations chemistry is at the heart of most analytical procedures to determine the rare earth content of both man-made and naturally occurring materials. Such procedures are widely used in mineral exploration, fundamental geology and geochemistry, material science, and in the nuclear industry. Chromatographic methods that rely on aqueous solutions containing complexing agents sensitive to the lanthanide cationic radius and cation-exchange phase transfer reactions (using a variety of different solid media) have enjoyed the greatest success for these procedures. In this report, they will briefly summarize the most important methods for completing such analyses. they consider in some detail the basic aqueous (and two-phase) solution chemistry that accounts for separations that work well and offer explanations for why others are less successful

  7. Ion-exchange chromatography separates activities synthesizing and degrading fructose 2,6-bisphosphate from C3 and C4 leaves but not from rat liver

    Science.gov (United States)

    Macdonald, F. D.; Chou, Q.; Buchanan, B. B.

    1987-01-01

    Fructose-6-phosphate,2-kinase and fructose-2,6-bisphosphatase were separated on the basis of charge from leaves of C3 (spinach, lettuce, and pea) and C4 (sorghum and amaranthus) plants but not from rat liver--a tissue known to contain a bifunctional enzyme with both activities. [2-32P]Fructose 2,6-bisphosphate binding experiments also suggest that the major forms of these activities reside on different proteins in leaves.

  8. Isotopic enrichment of 15N by ionic exchange cromatography

    International Nuclear Information System (INIS)

    The ionic exchange chromatographic method in columns of resin which is employed in the study of isotopic enrichment of 15N is presented. Determinations are made of the isotopic separation constant for the exchange of isotopes 15N and 14N in the equilibrium involving ammonium hidroxide in the solution phase and ions NH4+ adsorbed in cationic resins: Dowex 50W-X8 and X12, 100-200 mesh. Experiments are also conducted for determination of height of theoretical plates for situations of equilibrium of the NH4+ band in two systems of resin's columns aimed at estimating the experimental conditions used. The isotopic analyses of nitrogen are carried out by mass spectrometry

  9. Separation of clavulanic acid from fermented broth of amino acids by an aqueous two-phase system and ion-exchange adsorption.

    Science.gov (United States)

    da Silva, Clovis Sacardo; Cuel, Maressa Fabiano; Barreto, Verônica Orlandin; Kwong, Wu Hong; Hokka, Carlos O; Barboza, M

    2012-02-15

    The clavulanic acid is a substance which inhibits the β-lactamases used with penicillins for therapeutic treatment. After the fermentation, by-products of low molecular weight such as amino acids lysine, histidine, proline and tyrosine are present in the fermented broth. To remove these impurities the techniques of extraction by an aqueous two-phase system of 17% polyethylene glycol molecular weight 600 and 15% potassium phosphate were used for a partial purification. A subsequent ion-exchange adsorption was used for the recuperation of the clavulanic acid of the top phase and purification getting a concentration factor of 2 and purification of 100% in relation to the amino acids lysine, histidine, proline and tyrosine.

  10. Two different cationic positions in Cu-SSZ-13?

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Zhu, Haiyang; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos

    2012-04-18

    H2-TPR and FTIR were used to characterize the Cu ions present in Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions in two distinct cationic positions of the SSZ-13 framework.

  11. Two different cationic positions in Cu-SSZ-13?

    Science.gov (United States)

    Hun Kwak, Ja; Zhu, Haiyang; Lee, Jong H; Peden, Charles H F; Szanyi, János

    2012-05-16

    H(2)-TPR and FTIR were used to characterize the nature of the Cu ions present in the Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions at two distinct cationic positions in the SSZ-13 framework. PMID:22473309

  12. 丙烯酰胺与季铵类阳离子单体双水相共聚的二次相分离%DOUBLE PHASE SEPARATION OF AQUEOUS TWO-PHASE COPOLYMERIZATION OF ACRYLAMIDE WITH QUATERNARY AMMONIUM CATIONIC MONOMERS

    Institute of Scientific and Technical Information of China (English)

    商宽祥; 单国荣

    2012-01-01

    以(2-甲基丙烯酰氧乙基)三甲基氯化铵(DMC)为例,用分光光度法研究了丙烯酰胺(AM)与季铵类阳离子单体在聚乙二醇(PEG)水溶液中双水相共聚的二次相分离.提出了二次相分离的机理,认为是阳离子单体单元的电离使得聚合物带上了正电荷,大分子间的静电排斥作用增加了其在PEG相中的溶解性(增容作用).讨论了反应条件对体系二次相分离的影响,发现二次相分离在一定的单体浓度和PEG浓度、以及适当的单体比例和PEG分子量条件下才能发生.总单体用量或PEG用量增加,第二次分相先出现后消失;PEG分子量增大,第二次分相逐渐明显;反应温度升高,两次分相更快完成.DMC摩尔分率为0.25~ 0.60时,第一次分相的临界转化率很小,第二次分相的临界转化率则随DMC摩尔分率的增加而增大;DMC摩尔分率超过0.60后,聚合反应主要在过渡区完成,第二次分相难以发生.%In the aqueous two-phase copolymerization of acrylamide ( AM ) with quaternary ammonium cationic monomers, such as 2-methylacryloylxyethyl trimethyl ammonium chloride (DMC),in aqueous poly-(ethylene glycol) (PEG) solution a double phase separation process was observed. In order to fix the critical points,the spectrophotometer was employed to detect the transmittance of the copolymerization system on-line. The transmittance curves showed three intervals. At the first interval, the transmittance keeps constant at the beginning,and then drops off quickly. At the second interval, the transmittance stops dropping and begins to increase. And at the last interval,the transmittance stops to keep constant for a moment,and then drops rapidly to nearly zero. When acrylamide was copolymerized with different monomers, the double phase separation process can be observed only for DMC and acryloylxyethyl trimethyl ammonium chloride ( DAC ) . It confirms that the double phase separation is attributed to the cationic nature of

  13. A new method for separation and determination of Cr(III) and Cr(VI) in water samples by high-performance liquid chromatography based on anion exchange stationary phase of ionic liquid modified silica.

    Science.gov (United States)

    Sadeghi, Susan; Moghaddam, Ali Zeraatkar

    2015-12-01

    In this work, N-methylimidazolium-chloride ionic liquid functionalized silica was prepared and used as an anion-exchange stationary phase for separation of chromium species by high-performance liquid chromatography (HPLC) with UV detection at 200 nm. The Cr(VI) as HCr2O7(-) and chelated Cr(III) with potassium hydrogen phthalate (PHP) as Cr(PHP)2 (-) was retained on the prepared column and separated using a mobile phase composed of 5% methanol in 25 mM phosphate buffer at pH 6.5. Several variables affecting the chelation/separation steps were modeled by response surface methodology (RSM) using Box-Behnken (BBD) design. The significance of the independent variables and their interactions were tested by the analysis of variances (ANOVA) with 95% confidence limit. Under the optimized conditions, the Cr(III) and Cr(VI) anionic species were well separated with a single peak for each Cr species at retention times of 2.3 and 4.3 min, respectively. The relationship between the peak area and concentration was linear in the range of 0.025-30 for Cr(III) and 0.5-20 mg L(-1) for Cr(VI) with detection limits of 0.010 and 0.210 mg L(-1) for Cr(III) and Cr(VI), respectively. The proposed method was validated by simultaneous separation and determination of the Cr species in tap and underground water samples without impose to any pretreatment. PMID:26526699

  14. Electrohemical Properties of Carbon Nanotube Paste Electrodes Modified with Redox Cationic Dyes - doi: 10.4025/actascitechnol.v34i3.15250

    Directory of Open Access Journals (Sweden)

    Juliana Maria Ramos Antônio

    2012-05-01

    Full Text Available The present work describes the electrochemical behavior of cationic dyes (methylene blue and toluidine blue as electron mediators adsorbed in the multiwall carbon nanotubes paste in 0.5 KCl at pH 7.0 by using cyclic voltammetry. Based on midpoint potential [Em = (Eap + Ecp/2] and separation of cathodic and anodic peaks (ΔE, it was not observed interaction of different eletrolytes (LiCl, KCl, BaCl2, CaCl2, NaCl, NaNO3, Na2SO4 and NaClO4, with the cationic dyes by an ion exchange reaction and, as a consequence, absence of leaching of cationic dyes to the solution phase.  The kinetics of electron transfer on the surface electrode was not sufficiently fast showing a fairly resistence of carbon nanotube paste modified with the cationic dyes.  The midpoint potential and ΔE also were insentive to the pH range (4-8, confirming the protective effect of carbon nanotubes matrix, owing to strong interaction of between the latter and the nitrogen of nitrogen of cationic dyes with carbon nanotube matrix, minimizing the proton interaction under cationic dye. This result is very important for sensor/biosensor preparation, because the eletrooxidation behavior of the analyte will be only affected by its formal potencial shifting.  Carbon nanotubes proved to be an efficient solid matrix for the adsorption of mediator electron in comparison to the electrochemical behavior of free cationic dyes in solution phase.

  15. Competitive Effects of 2+ and 3+ Cations on DNA Compaction

    CERN Document Server

    Tongu, C; Yoshikawa, Y; Zinchenko, A A; Chen, N; Yoshikawa, K

    2016-01-01

    By using single-DNA observation with fluorescence microscopy, we observed the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA with 166 kbp). It was found that divalent cations, such as Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. These experimental observations are inconsistent with the well-established Debye-Huckel scheme regarding the shielding effect of counter ions, which is given as the additivity of contributions of cations with different valences. We interpreted the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counter ions before and after the folding transition of DNA. For the compaction with SPD(3+), we considered the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly-charged polyelectrolyte, double-st...

  16. 阳离子交换法制备稳定的近红外区核/壳型PbS/CdS量子点%Utilizing Cation Exchange Method to Produce Core/Shell PbS/CdS Quantum Dots with Stable Infrared Emission

    Institute of Scientific and Technical Information of China (English)

    李谦; 张腾; 古宏伟; 丁发柱; 屈飞; 彭星煜; 王洪艳; 吴战鹏

    2013-01-01

    硫化铅量子点(PbS QDs)的光氧化稳定性差是其应用于太阳能电池等领域的主要限制因素之一.采用阳离子交换法在合成的PbS量子点表面包裹一层具有更稳定、更大禁带宽度的硫化镉(CdS)壳层,制备出稳定的核/壳型PbS/CdS量子点;同时,研究了反应温度和反应时间对阳离子交换过程的影响规律.通过透射电子显微镜和高分辨透射电子显微镜(TEM/HRTEM)、X射线衍射仪(XRD)、吸收光谱和荧光光谱考察了所制备PbS/CdS量子点的结构、光学特性和光氧化稳定性,结果表明:阳离子交换过程中,离子交换反应程度有限、仅发生在量子点的表面层,但极薄的CdS壳层已能有效钝化PbS量子点的表面缺陷、显著提高其光氧化稳定性.%PbS quantum dots (QDs) have enormous potential for applications ranging from tunable infrared lasers to solar cells due to their efficient emission over a large spectral range in the infrared.Especially,multiple exciton generation has been observed in PbS QDs,which makes PbS QDs have great potential for high-efficiency solar cells.However,these applications have been limited by instability in emission quantum yield and peak position on exposure to ambient conditions.An effective strategy to improve PbS QDs' stability is overgrowth with a shell of a more stable semiconductor,such as CdS,resulting in core/shell PbS/CdS QDs.The PbS/CdS QDs were fabricated in a two-step method.In the first step,PbS QDs with a 4.8 nm diameter were prepared by using organic metal.Second,PbS/CdS QDs with 3.8 nm PbS core and 0.5 nm CdS shell were fabricated by exposing PbS QDs in Cd2+ solution for 24 h at 65 ℃.In this article,cation exchange method was adopted to moderate reaction temperature in a low temperature,so that Ostwald ripening in high temperature was avoided.The results of transmission electron microscopy (TEM) and high resolution TEM showed that PbS QDs were sphere and in a cubic cystal without obvious

  17. Simultaneous spectrophotometric determination of phosphate and silicate ions in river water by using ion-exclusion chromatographic separation and post-column derivatization

    OpenAIRE

    Nakatani, Nobutake; Kozaki, Daisuke; Masuda, Wakako; Nakagoshi, Nobukazu; Hasebe, Kiyoshi; Mori, Masanobu; Tanaka, Kazuhiko

    2008-01-01

    The simultaneous spectrophotometric determination of phosphate and silicate ions in river water was examined by using ion-exclusion chromatography and post-column derivatization. Phosphate and silicate ions were separated by the ion-exclusion column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the H+-form (TSKgel Super IC-A/C) by using ultra pure water as an eluent. After the postcolumn derivatization with molybdate and ascorbic acid, so-called molybdenum-blue, ...

  18. A separation of antiferromagnetic spin motion modes in the training effect of exchange biased Co/CoO film with in-plane anisotropy

    Science.gov (United States)

    Wu, R.; Yun, C.; Ding, S. L.; Wen, X.; Liu, S. Q.; Wang, C. S.; Han, J. Z.; Du, H. L.; Yang, J. B.

    2016-08-01

    The motion of antiferromagnetic interfacial spins is investigated through the temperature evolution of training effect in a Co/CoO film with in-plane biaxial anisotropy. Significant differences in the training effect and its temperature dependence are observed in the magnetic easy axis and hard axis (HA) and ascribed to the different motion modes of antiferromagnetic interfacial spins, the collective spin cluster rotation (CSR) and the single spin reversal (SSR), caused by different magnetization reversal modes of ferromagnetic layer. These motion modes of antiferromagnetic spins are successfully separated using a combination of an exponential function and a classic n-1/2 function. A larger CSR to SSR ratio and a shorter lifetime of CSR found in the HA indicates that the domain rotation in the ferromagnetic layer tends to activate and accelerate a CSR mode in the antiferromagnetic spins.

  19. Gas-phase folding and unfolding of cytochrome c cations.

    OpenAIRE

    Wood, T D; Chorush, R A; Wampler, F M; Little, D P; O'Connor, P B; McLafferty, F. W.

    1995-01-01

    Water is thought to play a dominant role in protein folding, yet gaseous multiply protonated proteins from which the water has been completely removed show hydrogen/deuterium (H/D) exchange behavior similar to that used to identify conformations in solution. Indicative of the gas-phase accessibility to D2O, multiply-charged (6+ to 17+) cytochrome c cations exchange at six (or more) distinct levels of 64 to 173 out of 198 exchangeable H atoms, with the 132 H level found at charge values 8+ to ...

  20. Modelling of cation concentrations in the outflow of NaNO3 percolation experiments through Boom Clay cores

    International Nuclear Information System (INIS)

    A laboratory percolation experiment was performed to study the effect of a NaNO3 plume on the Boom Clay. In this experiment, Boom Clay cores were consecutively percolated with Boom Clay pore water and Boom Clay pore water to which NaNO3 was added. The concentration of NaNO3 in the pore water was increased stepwise (0.1, 0.5, and 1 M NaNO3). The concentrations of Na, K, Ca, Mg and Sr in the eluted water were measured. After every switch of the NaNO3 concentration, the concentration profiles of K, Ca, Mg, and Sr showed a sharp rise, followed by a slow decrease. It was hypothesised that the cation elution curves are mainly determined by cation exchange processes. Reactive coupled transport modelling with the PHREEQC-2 code was used to describe the experimentally observed elution curves for the cations. Solute transport and water-clay interaction mechanisms, namely cation exchange, were accounted for in the model. Cation exchange parameters (cation exchange capacity and selectivity coefficients) previously determined on non-perturbed Boom Clay (De Craen et al., 2004) were used. A sensitivity analysis was performed to assess the influence of these parameter values on the goodness of the model to describe the experimental data. The model could fairly well describe the experimentally observed cation concentrations in the eluted water, confirming that cation exchange is indeed the dominant mechanism regulating the cation elution in the percolation experiments. (authors)

  1. [Separation mechanism of chiral stationary phase based on quinine and crown ether for the direct stereoselective separation of amino acids].

    Science.gov (United States)

    Wu, Haixia; Wang, Dongqiang; Zhao, Jianchao; Ke, Yanxiong; Liang, Xinmiao

    2016-01-01

    A novel chiral stationary phase combining quinine and crown ether (QN-CR CSP) was developed to separate amino acid enantiomers. This CSP showed good enantioselectivity for some amino acids. Since the synergistic effect of ion exchange and complexation in chiral recognition of amino acids, a new adsorption isotherm was built. Using the method of frontal analysis by characteristic point (FACP), the adsorption isotherms of tryptophan (Trp) under different mobile phase conditions were determined and fitted the proposed adsorption isotherm model well. With the increase of the competition between metal cationic and amino to crown ether, the equilibrium constant of complexing adsorption was found increased. The chiral separation ability was decreased. The adsorption isotherm improved the understanding of the retention behavior of amino acids on QN-CR CSP, which was also benefit to optimize the structure of the stationary phase.

  2. Advanced Aqueous Separation Systems for Actinide Partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Ken [Washington State Univ., Pullman, WA (United States); Martin, Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lumetta, Gregg [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-04-02

    necessary for commercial fuel processing supporting transmutation of transplutonium elements. This research project continued basic themes investigated by this research group during the past decade. In the Fuel Cycle Research and Development program at DOE, the current favorite process for accomplishing the separation of trivalent actinides from fission product lanthanides is the TALSPEAK process. TALSPEAK is a solvent extraction method (developed at Oak Ridge National Lab in the 1960s) based on the combination of a cation exchanging extractant (e.g., HDEHP), an actinide-selective aminopolycarboxylate complexing agent (e.g., DTPA), and a carboxylic acid buffer to control pH in the range of 3-4. Considerable effort has been expended in this research group during the past 8 years to elaborate the details of TALSPEAK in the interest of developing improved approaches to the operation of TALSPEAK-like systems. In this project we focused on defining aggregation phenomena in conventional TALSPEAK separations, on supporting the development of Advanced TALSPEAK processes, on profiling the aqueous complexation kinetics of lanthanides in TALSPEAK relevant aqueous media, on the design of new diglycolamide and N-donor extractants, and on characterizing cation-cation complexes of pentavalent actinides.

  3. A lanthanide complex for metal encapsulations and anion exchanges.

    Science.gov (United States)

    Sun, Yan-Qiong; Wan, Fang; Li, Xin-Xiong; Lin, Jian; Wu, Tao; Zheng, Shou-Tian; Bu, Xianhui

    2016-08-01

    A cationic lanthanide metalloligand with 3 dangling carboxylate groups on its periphery co-assembles with nitrate into a porous thermochromic solid responsive to both external cations and anions, owing to the presence of exchangeable NO3(-) as well as cation cavities arising from cooperative orientation of free carboxylate groups. An especially interesting feature is the structural memory effect during crystallization exhibited by the metalloligand, even after dissolution and binding to secondary cations (Cu(2+), Cd(2+)…). Moreover, the porous solid can undergo ion-exchange with various anions, leading to tunable thermochromic temperature and color range. PMID:27463609

  4. Copper cation removal in an electrokinetic cell containing zeolite.

    Science.gov (United States)

    Elsayed-Ali, Omar H; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E

    2011-01-30

    Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers. PMID:21109348

  5. FLOW AND HEAT TRANSFER CHARACTERISTICS IN SHELL SIDE OF SHELL-AND-TUBE HEAT EXCHANGERS WITH SEPARATED BAFFLES PARALLEL TO SEGMENTAL BAFFLES%平行流分隔板管壳式换热器壳侧流场与传热性能

    Institute of Scientific and Technical Information of China (English)

    王杨君; 邓先和; 陈颖; 李志武

    2004-01-01

    A shell-and-tube heat exchanger with separated baffles parallel to segmental baffles was proposed, and an investigation on velocity distribution, heat transfer and flow resistance characteristics in the shell side of the proposed heat exchanger and traditional single segmental baffled shell-and-tube heat exchanger was reported. After the experiment, the empirical relations of heat transfer and flow resistance were obtained. The heat transfer enhancement comprehensive evaluation factor η was in the range from 1.15 to 1.20 for Reynolds number (1.25×104-3.35×104). The resuhs indicated that flow field uniformization was enhanced in the shell side of shell-and-tube heat exchangers by two separated baffles parallel to segmental baffles and the performance of heat transfer was improved by controlling the dimension of vortices. The results could be used as reference in further research.

  6. 航空煤油在不同价态金属离子交换介孔材料上的深度吸附脱硫%Deep desulfurization of jet fuel by adsorption over mesoporous materials exchanged with different metal cations

    Institute of Scientific and Technical Information of China (English)

    邱国欢; 孟祥瑞; 王玉和

    2013-01-01

    Three adsorbents were prepared by exchanging Ag+, Ni2+ and Ce3+ onto the aluminized large-pore-size SBA-15 (SBA-15-L). Desulfurization of model jet fuel containing 0.015(wt)% S were carried out using fixed-bed reactor. The results showed that the jet fuel can be desulfurized to 0.000l(wt)%. The sulfur capacity of Ag/Al-SBA-15-L was stronger than that of Ni/Al-SBA-15-L and Ce/Al-SBA-15-L L ICP-AES results exhibited that the loadings of Ag+ on the sorbent were 13 and 65 times as large as that of Ni2+ and Ce3+. The experiments of desulfurization illustrated that the ratios of adsorbed sulfur per Ag+, Ni2+ and Ce3+ cation were 0.027, 0.570 and 0.752 at adsorption saturation. And then, it was showed that the inherent sulfur capacity of these metal cations followed the order: Ce3+ > Ni2+> Ag+.%采用离子交换法,将不同价态的金属离子Ag+,Ni2+,Ce3+交换到铝化的大孔径SBA-15介孔材料(SBA-15-L)上,制备了吸附剂Ag/Al-SBA-15-L,Ni/Al-SBA-15-L,Ce/Al-SBA-15-L.脱硫实验表明,所制备的吸附剂可将硫含量为0.015(wt)%的模拟航空煤油,脱硫至硫含量低于0.0001 (wt)%,并且Ag/Al-SBA-15-L的吸附脱硫能力强于Ni/Al-SBA-15-L和Ce/Al-SBA-15.通过ICP-AES分析表明,在铝化的大孔SBA-15上,Ag+的交换量分别是Ni2+和Ce3+的13和65倍.达到吸附饱和时,每个活性中心离子Ag+、Ni2+、Ce3+上可分别吸附0.027,0.570,0.752个硫原子,即金属离子固有的吸附脱硫能力为Ce3+> Ni2+> Ag+.

  7. Gaseous Hydrocarbon Separations Using Functionalized Ionic Liquids

    OpenAIRE

    Moura Leila; Santini Catherine C.; Costa Gomes Margarida F.

    2016-01-01

    The functionalization of the side chains on the cation or the anion of an ionic liquid is a common approach to tailor its properties for different processes including the separation of gases. In this paper, we present the current state of the art concerning the usage of ionic liquids for hydrocarbon separations. We also show how the functionalization of ionic liquids or the appropriate anion/cation combinations can contribute to the increase of the performance of the ionic liquids for the sep...

  8. Laboratory plant for the separation of cesium from waste solutions of the PUREX process

    International Nuclear Information System (INIS)

    A laboratory plant for the separation of cesium from a fission product waste solution of the fuel reprocessing is described. The plant consists of two stages. In the first stage cesium is adsorbed on ammonium molybdatophosphate (AMP). Then the adsorbent is dissolved. From the solution cesium is adsorbed on a cationic ion exchanger in the second stage. Then AMP can be reproduced from this solution. For the elution of cesium in the second stage a NH4NO3 solution (3 m) is used. Flow sheet, construction and the control device of the plant are described and the results of tests with a model solution are given. (author)

  9. Cations bind only weakly to amides in aqueous solutions.

    Science.gov (United States)

    Okur, Halil I; Kherb, Jaibir; Cremer, Paul S

    2013-04-01

    We investigated salt interactions with butyramide as a simple mimic of cation interactions with protein backbones. The experiments were performed in aqueous metal chloride solutions using two spectroscopic techniques. In the first, which provided information about contact pair formation, the response of the amide I band to the nature and concentration of salt was monitored in bulk aqueous solutions via attenuated total reflection Fourier transform infrared spectroscopy. It was found that molar concentrations of well-hydrated metal cations (Ca(2+), Mg(2+), Li(+)) led to the rise of a peak assigned to metal cation-bound amides (1645 cm(-1)) and a decrease in the peak associated with purely water-bound amides (1620 cm(-1)). In a complementary set of experiments, the effect of cation identity and concentration was investigated at the air/butyramide/water interface via vibrational sum frequency spectroscopy. In these studies, metal ion-amide binding led to the ordering of the adjacent water layer. Such experiments were sensitive to the interfacial partitioning of cations in either a contact pair with the amide or as a solvent separated pair. In both experiments, the ordering of the interactions of the cations was: Ca(2+) > Mg(2+) > Li(+) > Na(+) ≈ K(+). This is a direct cationic Hofmeister series. Even for Ca(2+), however, the apparent equilibrium dissociation constant of the cation with the amide carbonyl oxygen was no tighter than ∼8.5 M. For Na(+) and K(+), no evidence was found for any binding. As such, the interactions of metal cations with amides are far weaker than the analogous binding of weakly hydrated anions.

  10. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

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

    1983-07-21

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

  11. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

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

    1985-01-01

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

  12. Electron paramagnetic resonance line shifts and line shape changes due to heisenberg spin exchange and dipole-dipole interactions of nitroxide free radicals in liquids 8. Further experimental and theoretical efforts to separate the effects of the two interactions.

    Science.gov (United States)

    Peric, Mirna; Bales, Barney L; Peric, Miroslav

    2012-03-22

    The work in part 6 of this series (J. Phys. Chem. A 2009, 113, 4930), addressing the task of separating the effects of Heisenberg spin exchange (HSE) and dipole-dipole interactions (DD) on electron paramagnetic resonance (EPR) spectra of nitroxide spin probes in solution, is extended experimentally and theoretically. Comprehensive measurements of perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDT) in squalane, a viscous alkane, paying special attention to lower temperatures and lower concentrations, were carried out in an attempt to focus on DD, the lesser understood of the two interactions. Theoretically, the analysis has been extended to include the recent comprehensive treatment by Salikhov (Appl. Magn. Reson. 2010, 38, 237). In dilute solutions, both interactions (1) introduce a dispersion component, (2) broaden the lines, and (3) shift the lines. DD introduces a dispersion component proportional to the concentration and of opposite sign to that of HSE. Equations relating the EPR spectral parameters to the rate constants due to HSE and DD have been derived. By employing nonlinear least-squares fitting of theoretical spectra to a simple analytical function and the proposed equations, the contributions of the two interactions to items 1-3 may be quantified and compared with the same parameters obtained by fitting experimental spectra. This comparison supports the theory in its broad predictions; however, at low temperatures, the DD contribution to the experimental dispersion amplitude does not increase linearly with concentration. We are unable to deduce whether this discrepancy is due to inadequate analysis of the experimental data or an incomplete theory. A new key aspect of the more comprehensive theory is that there is enough information in the experimental spectra to find items 1-3 due to both interactions; however, in principle, appeal must be made to a model of molecular diffusion to separate the two. The permanent diffusion model is used to

  13. Unconventional exchange bias effect driven by phase separation in basically antiferromagnetic Sm{sub 0.1}Ca{sub 0.6}Sr{sub 0.3}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Markovich, V., E-mail: markoviv@bgu.ac.il [Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva (Israel); Fita, I. [Institute of Physics, Polish Academy of Sciences, PL-02-668 Warsaw (Poland); Donetsk Institute for Physics and Technology, National Academy of Sciences, 83114 Donetsk (Ukraine); Wisniewski, A.; Puzniak, R.; Iwanowski, P. [Institute of Physics, Polish Academy of Sciences, PL-02-668 Warsaw (Poland); Martin, C. [Laboratoire CRISMAT, UMR 6508, ISMRA, 14050 Caen Cedex (France); Gorodetsky, G. [Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva (Israel); Jung, G. [Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva (Israel); Institute of Physics, Polish Academy of Sciences, PL-02-668 Warsaw (Poland)

    2015-02-15

    Highlights: • Sm{sub 0.1}Ca{sub 0.6}Sr{sub 0.3}MnO{sub 3} displays negative exchange bias (NEB) effect at low temperatures. • The NEB increases rapidly with increasing H{sub cool} up to 100 Oe, but is almost H{sub cool} independent at H > 0.5 kOe. • The sign of the EB changes with temperature from NEB at T < 40 K to a positive one at T ⩾ 40 K. • The atypical magnetic properties are related to two different interfaces appearing between coexisting magnetic phases. - Abstract: Magnetic investigations, focused on the uncommon behavior of the exchange bias (EB) effect, have been performed for basically antiferromagnetic (AFM) electron doped manganite Sm{sub 0.1}Ca{sub 0.6}Sr{sub 0.3}MnO{sub 3}. The studied system in the ground state exhibits a heterogeneous spin configuration consisting of the C-type antiferromagnetic phase with the Néel temperature T{sub N-C} ≈ 150 K, the G-type AFM phase with the Néel temperature T{sub N-G} ≈ 70 K, and a FM-like phase with very weak spontaneous magnetic moment. The phase separation, into two different AFM phases and a FM-like phase at the temperatures below T{sub N-G}, leads to unusual magnetic properties, such as: narrowing of magnetic hysteresis loops in field cooling process, unconventional EB effect associated with spontaneous magnetization at temperatures below T{sub N-C}, strong magnetic field dependence of the negative exchange bias at fields below 100 Oe turning into practically field independent one for fields above 0.5 kOe, significant shift of EB with temperature with a change of the sign from negative at 10 K to positive above 40 K. The atypical magnetic properties are discussed and related to two different interfaces appearing between coexisting magnetic phases.

  14. Cation exchange and adsorption on clays and clay minerals

    OpenAIRE

    Ammann, Lars

    2003-01-01

    The specific surface area of a clay mineral comprises the external and internal surface area and, finally, the surface area which is exposed to the solution (Chap. 6.1). The aim of this study was to correlate adsorption data of common clays with these specific surface areas.

  15. Separation and characterization of anti-benzylpenicilloyl (BPO) antibodies. I. Biochemical and biophysical properties of anti-BPO-IgG obtained by affinity and subsequent ion-exchange chromatography.

    Science.gov (United States)

    Scheiner, O; Stemberger, H; Kraft, D; Wiedermann, G

    1978-01-01

    Anti-BPO antibodies were purified by means of affinity chromatography using AH-Sepharose 4B coated with covalently bound BPO groups. Specific elution was achieved by the hapten analogue BPO-epsilon-aminocaproic acid (BPO-EACA); desorption of the remaining antibody was performed thereafter by 0.1 M acetic acid. The resulting antibody fractions--hapten-eluted antibody (H-Ab) and acid eluted antibody (A-Ab), respectively--were further separated by ion-exchange chromatography which led to the appearance of 3 subfractions in the case of H-Ab (H1, H2, H3) and 2 subfractions in the case of A-Ab (A1 and A2). In liquid isoelectrofocusing an inhomogeneous pattern resulted. The bulk of antibodies focused between pH 6.5 and 7.0. The average avidity of H-Ab was found to be higher than that of A-Ab suggesting that avidity may influence the elution pattern in affinity chromatography. The hydrophobic influence of the "spacer" and/or interactions of antibodies directed against the hydrophobic regions of the BPO group may explain why a considerable part of the antibodies could be recovered from the immunosorbent only by acid elution.

  16. Metal cations inserted in vanadium-oxide nanotubes

    International Nuclear Information System (INIS)

    Vanadium-oxide nanotubes (VO x-NTs) consist of nanosize cylinders of thin, easily bent vanadyl (VO x) wall chains, which are open at both ends. Surfactant molecules (e.g. C12H27N) can be easily trapped in the interior of the nanotube walls. The structure of as-synthesized VO x-NTs are observed to collapse to an amorphous vanadium oxide at temperatures greater than 250 deg, C. This happens, even under a protective atmosphere. This property makes the VO x-NTs unusable as a catalyst at temperatures between 400-500 deg, C, which is the temperature range where many applications would exist. In order to increase the thermal stability of VO x-NTs several exchange reactions have been used to modify the original nanotubes. In these reactions metallic cations (Cd2+, Co2+, Mn2+ or Zn2+) were introduced. It was observed that that the morphology of the nanotubes remained unchanged after the exchange reactions were performed. In order to characterize the exchanged VO x-NTs the following analytic techniques were used: scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared, particle-induced X-ray emission and Rutherford backscattering spectrometry. The results showed that the VO x-NTs exchanged with metallic cations have preserved their tubular morphology. However, it has not been possible to fully perform a 100% efficient exchange reaction

  17. Lithium isotope separation

    International Nuclear Information System (INIS)

    Published methods for 6Li-7Li lithium isotope separation have been reviewed. Future demand for 6Li, whose main use will be as a tritium breeder in blankets surrounding the core of DT fusion power reactors, is likely to exceed 5 Mg/a in the next century. The applicability of the various available methods to such a large scale production rate has been assessed. Research on improving the effectiveness of current lithium isotope separation processes has been carried out worldwide in several major areas during the past decade; these include two-phase chemical exchange systems, ion exchange resin chromatography, highly isotope-selective techniques like laser photoactivation and radiofrequency spectroscopy. Chemical exchange systems appear to offer good potential in the near term for 6Li enrichment

  18. Morphology of sulfonated polyimide ionomers from ESR spectra of paramagnetic transition metal cations and nitroxide spin probes

    International Nuclear Information System (INIS)

    We present a study of sulfonated polyimide block ionomer membranes (SPIs) in the dry state, and swollen by water, methanol, ethanol, and dioxane. The ionomers are based on a naphthalenic dianhydride, and differ in the ionic exchange capacity and the type of diamine in the hydrophobic block. The ionomers were studied by electron spin resonance (ESR) spectroscopy of the paramagnetic transition metal cations Cu+ and VO2+, and of two nitroxide spin probes. The results indicated the existence of separate hydrophobic and hydrophilic domains in the dry and in the swollen membranes. Water clusters with a diameter + or K+. The irreversible increase of the signal intensity upon heating of the dry membranes above 360 K suggests the formation of reactive intermediates that may be involved in ionomer degradation processes. (author)

  19. Forest-soil response to acid and salt additions of sulfate. 2. Aluminum and base cations

    International Nuclear Information System (INIS)

    Reconstructed spodosol and intact alfisol soil columns were used to examine the effects of 52 weeks of additions of various simulated throughfall solutions on base cation, Al, acid neutralizing capacity, and pH levels in soil leachates. The work illustrates the importance of soil cation exchange (especially in the forest floor), anion concentrations, and pCO2 levels in controlling the leachate chemistry in response to acidic and 'seasalt' deposition events

  20. Exchange Equilibria on the Surface of Ionic Crystals

    International Nuclear Information System (INIS)

    New experimental data obtained by tracer techniques are presented and discussed. The number of exchanging cations and anions per unit area on the surface of BaSO4 and SrSO4 was measured for equivalent particles, cationic particles and anionic particles. Equivalent particles obtained by washing the precipitates thoroughly with water showed constant ratios of exchanging cations and anions per unit area of the surface. For cationic particles and anionic particles obtained by treatmeni of the precipitates with solutions containing barium ions or sulphate ions respectively, the ratio of the numbers of exchanging cations and anions was changed to higher values (cationic particles) or to lower values (anionic particles). From the values obtained the number of potential determining ions on the surface was determined. In the case of SrSO4 the numbers of exchanging cations and anions per unit area of the surface were measured as a function of temperature. They were found to decrease rapidly below 40°C in water solutions. This is explained by the immobilization of the water molecules on special points of the surface (in cracks for instance) proceeding gradually on approaching the freezing point. In agreement with this explanation the immobilization starts at lower temperatures for water-methanol mixtures. The exchange equilibria between different cations have been measured on the surface of the alkaline earth carbonates and sulphates and on the surface of the alkali tetraphenylborates. The equilibrium constants for these heterogeneous exchange reactions are discussed. In general these equilibria show the same trend as the solubilities. Barium ions, for instance, are enriched on the surface of strontium sulphate. The ratio of the solubilities, however, is no measure for these equilibria. The exchange equilibria on the surface of the alkaline earth sulphates show ''ideal'' behaviour; they are independent of the lattice parameters. (author)