These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Method of separating uranium from iron and thorium  

Microsoft Academic Search

Acid leaching of uranium deposits is not a selective process. Sulfuric acid solubilizes iron(III) and half or more of the thorium depending on the mineralog of this element. In uranium recovery by solvent extraction process, uranium is separated from iron by an organic phase consisting of 10 vol% tributylphosphate(TBP) in kerosine diluent. Provided that the aqueous phase is saturated with

H. Movaseghi

1986-01-01

2

Uranium Metal Analysis via Selective Dissolution  

SciTech Connect

Uranium metal, which is present in sludge held in the Hanford Site K West Basin, can create hazardous hydrogen atmospheres during sludge handling, immobilization, or subsequent transport and storage operations by its oxidation/corrosion in water. A thorough knowledge of the uranium metal concentration in sludge therefore is essential to successful sludge management and waste process design. The goal of this work was to establish a rapid routine analytical method to determine uranium metal concentrations as low as 0.03 wt% in sludge even in the presence of up to 1000-fold higher total uranium concentrations (i.e., up to 30 wt% and more uranium) for samples to be taken during the upcoming sludge characterization campaign and in future analyses for sludge handling and processing. This report describes the experiments and results obtained in developing the selective dissolution technique to determine uranium metal concentration in K Basin sludge.

Delegard, Calvin H.; Sinkov, Sergey I.; Schmidt, Andrew J.; Chenault, Jeffrey W.

2008-09-10

3

Separation of Uranium from (Th,U)O sub 2 Solid Solutions.  

National Technical Information Service (NTIS)

Uranium is separated from mixed oxides of thorium and uranium by a pyrometallurgical process in which the oxides are mixed with a molten chloride salt containing thorium tetrachloride and thorium metal which reduces the uranium oxide to uranium metal whic...

P. Chiotti, M. C. Jha

1976-01-01

4

Uranium\\/plutonium and uranium\\/neptunium separation by the Purex process using hydroxyurea  

Microsoft Academic Search

Hydroxyurea dissolved in nitric acid can strip plutonium and neptunium from tri-butyl phosphate efficiently and has little\\u000a influence on the uranium distribution between the two phases. Simulating the 1B contactor of the Purex process by hydroxyurea\\u000a with nitric acid solution as a stripping agent, the separation factors of uranium\\/plutonium and uranium\\/neptunium can reach\\u000a values as high as 4.7. 104 and

Zhu Zhaowu; He Jianyu; Zhang Zefu; Zhang Yu; Zhu Jianmin; Zhen Weifang

2004-01-01

5

Electrochemical separation of aluminum from uranium for research reactor spent nuclear fuel applications.  

SciTech Connect

Researchers at Argonne National Laboratory (ANL) are developing an electrorefining process to treat aluminum-based spent nuclear fuel by electrochemically separating aluminum from uranium. The aluminum electrorefiner is modeled after the high-throughput electrorefiner developed at ANL. Aluminum is electrorefined, using a fluoride salt electrolyte, in a potential range of -0.1 V to -0.2 V, while uranium is electrorefined in a potential range of -0.3 V to -0.4 V; therefore, aluminum can be selectively separated electrochemically from uranium. A series of laboratory-scale experiments was performed to demonstrate the aluminum electrorefining concept. These experiments involved selecting an electrolyte (determining a suitable fluoride salt composition); selecting a crucible material for the electrochemical cell; optimizing the operating conditions; determining the effect of adding alkaline and rare earth elements to the electrolyte; and demonstrating the electrochemical separation of aluminum from uranium, using a U-Al-Si alloy as a simulant for aluminum-based spent nuclear fuel. Results of the laboratory-scale experiments indicate that aluminum can be selectively electrotransported from the anode to the cathode, while uranium remains in the anode basket.

Slater, S. A.; Willit, J. L.; Gay, E. C.; Chemical Engineering

1999-01-01

6

Extractive separation of uranium and zirconium sulfates by amines  

SciTech Connect

This paper describes an amine extraction process for zirconium and uranium separation. The behaviour of an extraction system containing uranium (VI) sulfate, zirconium (IV) sulfate, 0.2 and 0.5 M sulfuric acid (as the original aqueous phase), tertiary amine tri-n-lauryl- amine or primary amine Primene JMT in benzene (as the original organic phase) is discussed on the basis of equilibrium data. The measured dependences show that the degree of extraction of zirconium at the sulfuric acid concentration of 0.5 M and above is only slightly affected by a presence of uranium in solution. From this surprising behaviour it follows that zirconium may be employed for the displacement of uranium from the organic phase. This effect is more pronounced with the primary amine Primene JMT than with TLA. 29 refs., 4 figs., 1 tab.

Schroetterova, D.; Nekovar, P.; Mrnka, M. [Prague Inst. of Chemical Technology (Czechoslovakia)

1992-04-01

7

Cost analyses of uranium enrichment by laser isotope separation process  

Microsoft Academic Search

The probability of the selective two-step photoionisation of 235U atoms by laser and ultraviolet radiations is estimated from the rate equations for uranium atoms with two isotopes with three levels. The population of 235U ions is obtained by linearising the rate equations. We have calculated the ion production rates for three cases in which the laser and ultraviolet powers are

Norihiko Ozaki; Kimio Yamada; Manabu Yamamoto; Shunsuke Tomiyama; Kiichi Ueyanagi

1976-01-01

8

Separation of uranium and molybdenum using a solvent  

SciTech Connect

A process for separating by means of an organic agent the uranium and the molybdenum contained in an aqueous liquor originating from a sulphuric attack of an urano-molybdeniferous ore which involves placing the said attacking liquor in contact with an organic extraction solution containing at least one tertiary or secondary amine in an (amine)/(Mo) molar ratio of up to 0.8, separating the molybdenum-charged organic phase from the uranium-rich aqueous phase, treating the organic phase with an aqueous liquor containing at least one mineral agent in the form of alkaline and ammonium hydroxide and/or carbonates to form an aqueous solution which is concentrated in molybdate.

Cuer, J.; Floreancig, A.

1982-12-14

9

Separation of Metal Pairs using Bis (2-Ethylhexyl) Phosphoric Acid (HDEHP); Separation of Cerium from Uranium and from Thorium  

Microsoft Academic Search

A systematic study was performed on the extraction and separation of uranium-cerium and thorium-cerium pairs for HDEHP from pure hydrochloric and sulphuric acid solutions as well as from their binary mixtures. The effect of water miscible alcohols and actone on the separation of these elements was also investigated. The separation of uranium and thorium from macroamounts of cerium can be

A. M. El-Kot

1991-01-01

10

Separation and ?-Spectrometric Determination of the Isotopic Compositions of Uranium, Protactinium and Thorium and Their Applications on Dating Uranium Glass  

Microsoft Academic Search

A flow sheet for the isolation of uranium, thorium and protactinium with high radiochemical purity from uranium matrices was developed. The isotopic compositions and the chemical yield of the different metal ions separated were determined by ?-spectroscopy and isotopic dilution, respectively. The developed flow sheet was applied to analyse two uranium matrices, namely: a pitchblende mineral from Atabaska, Canada and

H. F. Aly; M. M. El-Dessouky

1985-01-01

11

Membrane selective separation of binary gas mixtures  

Microsoft Academic Search

A general approach to solving a conjugate problem of mass transfer in the separation of binary gas mixtures in selectively\\u000a permeable membrane elements with allowance for the external convective and intramembrane diffusion resistances is suggested.

V. I. Baikov; N. V. Primak

2007-01-01

12

SASSE MODELING OF A URANIUM MOLYBDENUM SEPARATION FLOWSHEET  

SciTech Connect

H-Canyon Engineering (HCE) is evaluating the feasibility of processing material from the Super Kukla Prompt Burst Reactor, which operated at the Nevada Test Site from 1964 to 1978. This material is comprised of 90 wt % uranium (U) (at approximately 20% 235U enrichment) alloyed with 10 wt % molybdenum (Mo). The objective is to dissolve the material in nitric acid (HNO{sub 3}) in the H-Canyon dissolvers and then to process the dissolved material through H-Canyon First and Second Cycle solvent extraction. The U product from Second Cycle will be sent to the highly enriched uranium (HEU) blend down program. In the blend down program, enriched U from the 1EU product stream will be blended with natural U at a ratio of 1 part enriched U per 3.5 parts natural U to meet a reactor fuel specification of 4.95% 235U before being shipped for use by the Tennessee Valley Authority (TVA) in its nuclear plants. The TVA specification calls for <200 mg Mo/g U (200 ppm). Since natural U has about 10 mg Mo/g U, the required purity of the 1EU product prior to blending is about 800 mg Mo/g U, allowing for uncertainties. HCE requested that the Savannah River National Laboratory (SRNL) define a flowsheet for the safe and efficient processing of the U-10Mo material. This report presents a computational model of the solvent extraction portion of the proposed flowsheet. The two main objectives of the computational model are to demonstrate that the Mo impurity requirement can be met and to show that the solvent feed rates in the proposed flowsheet, in particular to 1A and 1D Banks, are adequate to prevent refluxing of U and thereby ensure nuclear criticality safety. SASSE (Spreadsheet Algorithm for Stagewise Solvent Extraction), a Microsoft Excel spreadsheet that supports Argonne National Laboratory's proprietary AMUSE (Argonne Model for Universal Solvent Extraction) code, was selected to model the U/Mo separation flowsheet. SASSE spreadsheet models of H-Canyon First and Second Cycle solvent extraction show that a standard unirradiated fuel flowsheet is capable of separating U from Mo in dissolved solutions of a U/Mo alloy. The standard unirradiated fuel flowsheet is used, except for increases in solvent feed rates to prevent U refluxing and thereby ensure nuclear criticality safety and substitution of higher HNO{sub 3} concentrations for aluminum nitrate (Al(NO{sub 3})){sub 3} in the feed to 1A Bank. (Unlike Savanah River Site (SRS) fuels, the U/Mo material contains no aluminum (Al). As a result, higher HNO3 concentrations are required in the 1AF to provide the necessary salting.) The TVA limit for the final blended product is 200 {micro}g Mo/g U, which translates to approximately 800 mg Mo/g U for the Second Cycle product solution. SASSE calculations give a Mo impurity level of 4 {micro}g Mo/g U in the Second Cycle product solution, conservatively based on Mo organic-to-aqueous distributions measured during minibank testing for previous processing of Piqua reactor fuel. The calculated impurity level is slightly more than two orders of magnitude lower than the required level. The Piqua feed solution contained a significant concentration of Al(NO{sub 3}){sub 3}, which is not present in the feed solution for the proposed flowsheet. Measured distribution data indicate that, without Al(NO{sub 3}){sub 3} or other salting agents present, Mo extracts into the organic phase to a much lesser extent, so that the overall U/Mo separation is better and the Mo impurities in the Second Cycle product drop to negligible concentrations. The 1DF U concentration of 20 g/L specified by the proposed flowsheet requires an increased 1DX organic feed rate to satisfy H-Canyon Double Contingency Analysis (DCA) guidelines for the prevention of U refluxing. The ranges for the 1AX, 1BS, and 1DX organic flow rates in the proposed flowsheet are set so that the limiting ratios of organic/aqueous flow rates exactly meet the minimum values specified by the DCA.

Laurinat, J

2007-05-31

13

Surface selective membranes for carbon dioxide separation  

SciTech Connect

In this study, hybrid membranes have been developed for the selective separation of CO2 from mixtures containing H2. Beginning with commercially available Pall alumina membrane tubes with nominal pore diameter of 5 nm, hybrids were produced by silation with a variety of functionalities designed to facilitate the selective adsorption of CO2 onto the pore surface. The goal is to produce a membrane which can harness the power of surface diffusion to give the selectivity of polymer membranes with the permeance of inorganic membranes.

Luebke, D.R.; Pennline, H.W.; Myers, C.R.

2005-09-01

14

Method of separating and recovering uranium and related cations from spent Purex-type systems  

DOEpatents

A process for separating uranium and related cations from a spent Purex-type solvent extraction system which contains degradation complexes of tributylphosphate wherein the system is subjected to an ion-exchange process prior to a sodium carbonate scrubbing step. A further embodiment comprises recovery of the separated uranium and related cations. 5 figs.

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

1987-02-25

15

Selective elution of uranium from amidoxime polymer. I  

SciTech Connect

The separative elution of uranium from an amidoxime polymer was examined by the column method with hydrochloric acid solutions. The amidoxime polymer was immersed in seawater for 40 d for preparation of an uranium-loaded polymer sample for the elution experiments; the metal ions adsorbed were Mg(II), Ca(II), Fe(III), Ni(II), Cu(II), and Zn(II) as well as UO/sub 2/(VI). It was found from the pH dependence of elution extent by a batch method that the order of elution pH values is Fe(III) < UO/sub 2/(VI) < Cu(II) < Ni(II) < Zn(II) < Ca(II) < Mg(II). In the elution by a column method, Mg(II), Ca(II), Zn(II), and Ni(II) were eluted completely by 0.1 M HCl and the eluate of enriched uranium was obtained by a succeeding elution with 0.5 or 1 M HCl. This eluate contained Cu(II) and Fe(III), which could be removed in the succeeding step. The elution treatment with hydrochloric acid solutions hardly affected the adsorptivity for uranium in seawater. It was suggested that the elution of uranium with hydrochloric acid solutions from amidoxime polymers is satisfactorily applicable to uranium elution in the recovery of uranium from seawater with amidoxime polymers.

Hirotsu, T.; Katoh, S.; Sugasaka, K.; Takai, N.; Seno, M.; Itagaki, T.

1987-07-01

16

Permeation Rate in Selective Membrane Gas Separation  

NASA Astrophysics Data System (ADS)

The procedure of calculation of the permeation rate in membrane selective separation of binary gas mixtures with allowance for the convective external and intramembrane diffusion resistances has been proposed. The calculated concentration distributions in the membrane pressure channel have been compared to the literature experimental data; their satisfactory agreement has been shown. The ordinary nonlinear differential equation of first order for the permeation rate as a function of the physical properties of a binary gas mixture and the parameters of a membrane element has been solved.

Baikov, V. I.; Primak, N. V.

2008-05-01

17

Separation of uranium from technetium in recovery of spent nuclear fuel  

SciTech Connect

Uranium and technetium in the product stream of the Purex process for recovery of uranium in spent nuclear fuel are separated by (1) contacting the aqueous Purex product stream with hydrazine to reduce Tc/sup +7/ therein to a reduced species, and (2) contacting said aqueous stream with an organic phase containing tributyl phosphate and an organic diluent to extract uranium from said aqueous stream into said organic phase.

Pruett, D.J.; McTaggart, D.R.

1984-04-17

18

Selective solid-phase extraction of uranium by salicylideneimine-functionalized hydrothermal carbon.  

PubMed

A new salicylideneimine-functionalized hydrothermal-carbon-based solid-phase extractant was developed for the purpose of separating uranium selectively for sustainability of uranium resources. The resulting adsorption material was obtained via hydrothermal carbonization, calcination at mild temperature (573.15K), amination, and grafting with salicylaldehyde in sequence. Both Fourier transform infrared spectra and elemental analysis proved the successful grafting of salicylideneimine onto hydrothermal carbon matrix. Adsorption behaviors of the extractant on uranium(VI) were investigated by varying pH values of solution, adsorbent amounts, contact times, initial metal concentrations, temperatures, and ionic strengths. An optimum adsorption capacity of 1.10 mmol g(-1) (261 mg g(-1)) for uranium(VI) was obtained at pH 4.3. The present adsorption process obeyed pseudo-second-order model and Langmuir isotherm. Thermodynamic parameters (?H=+8.81 kJ mol(-1), ?S=+110 J K(-1)mol(-1), ?G=-23.0 kJ mol(-1)) indicated the adsorption process was endothermic and spontaneous. Results from batch adsorption test in simulated nuclear industrial effluent, containing Cs(+), Sr(2+), Ba(2+), Mn(2+), Co(2+), Ni(2+), Zn(2+), La(3+), Ce(3+), Nd(3+), Sm(3+), and Gd(3+), showed the adsorbent could separate uranium(VI) from those competitive ions with high selectivity. The adsorbent might be promising for use in certain key steps in any future sustainable nuclear fuel cycle. PMID:22770585

Wang, Hang; Ma, Lijian; Cao, Kecheng; Geng, Junxia; Liu, Jun; Song, Qiang; Yang, Xiaodan; Li, Shoujian

2012-08-30

19

Separation and Recovery of Uranium Metal from Spent Light Water Reactor Fuel via Electrolytic Reduction and Electrorefining  

SciTech Connect

A series of bench-scale experiments was performed in a hot cell at Idaho National Laboratory to demonstrate the separation and recovery of uranium metal from spent light water reactor (LWR) oxide fuel. The experiments involved crushing spent LWR fuel to particulate and separating it from its cladding. Oxide fuel particulate was then converted to metal in a series of six electrolytic reduction runs that were performed in succession with a single salt loading of molten LiCl – 1 wt% Li2O at 650 °C. Analysis of salt samples following the series of electrolytic reduction runs identified the diffusion of select fission products from the spent fuel to the molten salt electrolyte. The extents of metal oxide conversion in the post-test fuel were also quantified, including a nominal 99.7% conversion of uranium oxide to metal. Uranium metal was then separated from the reduced LWR fuel in a series of six electrorefining runs that were performed in succession with a single salt loading of molten LiCl-KCl-UCl3 at 500 °C. Analysis of salt samples following the series of electrorefining runs identified additional partitioning of fission products into the molten salt electrolyte. Analyses of the separated uranium metal were performed, and its decontamination factors were determined.

S. D. Herrmann; S. X. Li

2010-09-01

20

Sequential separation of lanthanides, thorium and uranium using novel solid phase extraction method from high acidic nuclear wastes  

Microsoft Academic Search

A novel grafted polymer for selective extraction and sequential separation of lanthanides, thorium and uranium from high acidic wastes has been developed by grafting Merrifield chloromethylated (MCM) resin with octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) (MCM-CMPO). The grafting process is well characterized using FT-IR spectroscopy, 31P and 13C CPMAS (cross-polarized magic angle spin) NMR spectroscopy and CHNPS elemental analysis. The influence of various

Ch. Siva Kesava Raju; M. S. Subramanian

2007-01-01

21

Selective elution of uranium from amidoxime polymer. II  

SciTech Connect

A separative elution of uranium from an amidoxime polymer which had been immersed in sea water was examined on its relation with the flow rate of acidic eluent. The elution with 0.5 M HCl at S.V. < 1 h/sup -1/ or with 1.0 M HCl at S.V. < 3 h/sup -1/, which was started from the elution by 16.5 LL/sub rho/ of 0.1 M HCl at S.V. < 3 h/sup -1/, provided an eluate containing more than 80% of uranium adsorbed and separating from other metal ions except Fe(III) and Cu(II). The efficiency of uranium elution was hardly affected by the scale of the system employed. Acid consumption, which occurred predominantly in the elution with 0.1 M HCl, was approx. 1.4 molL/sub rho/. The results suggest that this elution method is promising in the recovery of uranium from sea water

Hirotsu, T.; Takagi, N.; Katoh, S.; Sugasaka, K.; Takai, N.; Seno, M.; Itagaki, T.

1987-11-01

22

Ion separation by selective crystallization of organic frameworks  

SciTech Connect

Selective crystallization of organic frameworks is presented as a promising alternative to ion separation from competitive aqueous environments. The review focuses primarily on the principles determining ion selectivity in crystallization, as well as on structure-selectivity relationships. Specific examples involving anion separation by selective crystallization are discussed.

Custelcean, Radu [ORNL

2009-01-01

23

Laser isotope separation: Non-uranium applications. January 1976-November 1989 (A Bibliography from the Searchable Physics Information Notices data base). Report for January 1976-November 1989  

SciTech Connect

This bibliography contains citations concerning research and development of laser isotope separation technology for other than uranium applications. Applications for boron, hydrogen, nitrogen, potassium, and sulfur are among the elements included. Thermal effects generated by the laser on the separation process, selectivity of dissociation, efficiency evaluations of the separation process, and theoretical investigations into the process are also included. (This updated bibliography contains 165 citations, 65 of which are new entries to the previous edition.)

Not Available

1990-02-01

24

Separation of uranium from technetium in recovery of spent nuclear fuel  

DOEpatents

A method for decontaminating uranium product from the Purex process comprises addition of hydrazine to the product uranyl nitrate stream from the Purex process, which contains hexavalent (UO.sub.2.sup.2+) uranium and heptavalent technetium (TcO.sub.4 -). Technetium in the product stream is reduced and then complexed by the addition of oxalic acid (H.sub.2 C.sub.2 O.sub.4), and the Tc-oxalate complex is readily separated from the uranium by solvent extraction with 30 vol. % tributyl phosphate in n-dodecane.

Friedman, Horace A. (Oak Ridge, TN)

1985-01-01

25

Separation of uranium from technetium in recovery of spent nuclear fuel  

DOEpatents

A method for decontaminating uranium product from the Purex 5 process comprises addition of hydrazine to the product uranyl nitrate stream from the Purex process, which contains hexavalent (UO/sub 2//sup 2 +/) uranium and heptavalent technetium (TcO/sub 4/-). Technetium in the product stream is reduced and then complexed by the addition of oxalic acid (H/sub 2/C/sub 2/O/sub 4/), and the Tc-oxalate complex is readily separated from the 10 uranium by solvent extraction with 30 vol % tributyl phosphate in n-dodecane.

Friedman, H.A.

1984-06-13

26

Separation of uranium from technetium in recovery of spent nuclear fuel  

SciTech Connect

A method for decontaminating uranium product from the Purex process comprises addition of hydrazine to the product uranyl nitrate stream from the Purex process, which contains hexavalent (UO2S+) uranium and heptavalent technetium (TcO4-). Technetium in the product stream is reduced and then complexed by the addition of oxalic acid (H2C2O4), and the Tc-oxalate complex is readily separated from the uranium by solvent extraction with 30 vol. % tributyl phosphate in n-dodecane.

Friedman, H.A.

1985-07-09

27

Depleted uranium particles in selected Kosovo samples  

Microsoft Academic Search

Selected soil samples, collected in Kosovo locations where DU ammunition was expended during the 1999 Balkan conflict, have been investigated by secondary ion mass spectrometry (SIMS), X-ray fluorescence imaging using a micro-beam (?-XRF) and scanning electron microscopy equipped with an energy dispersive X-ray fluorescence detector (SEM-EDXRF), with the objective to test the suitability of these techniques to identify the presence

P. R Danesi; A Markowicz; E Chinea-Cano; W Burkart; B Salbu; D Donohue; F Ruedenauer; M Hedberg; S Vogt; P Zahradnik; A Ciurapinski

2003-01-01

28

Selection of a management strategy for depleted uranium hexafluoride  

SciTech Connect

A consequence of the uranium enrichment process used in the United States (US) is the accumulation of a significant amount of depleted uranium hexafluoride (UF{sub 6}). Currently, approximately 560,000 metric tons of the material are stored at three different sites. The US Department of Energy (DOE) has recently initiated a program to consider alternative strategies for the cost-effective and environmentally safe long-term management of this inventory of depleted UF{sub 6}. The program involves a technology and engineering assessment of proposed management options (use/reuse, conversion, storage, or disposal) and an analysis of the potential environmental impacts and life-cycle costs of alternative management strategies. The information obtained from the studies will be used by the DOE to select a preferred long-term management strategy. The selection and implementation of a management strategy will involve consideration of a number of important issues such as environmental, health, and safety effects; the balancing of risks versus costs in a context of reduced government spending; socioeconomic implications, including effects on the domestic and international uranium industry; the technical status of proposed uses or technologies; and public involvement in the decision making process. Because of its provisions for considering a wide range of relevant issues and involving the public, this program has become a model for future DOE materials disposition programs. This paper presents an overview of the Depleted Uranium Hexafluoride Management Program. Technical findings of the program to date are presented, and major issues involved in selecting and implementing a management strategy are discussed.

Patton, S.E.; Hanrahan, E.J.; Bradley, C.E.

1995-09-06

29

Supercritical fluid extraction and separation of uranium from other actinides.  

PubMed

The feasibility of separating U from nitric acid solutions of mixed actinides using tri-n-butylphosphate (TBP)-modified supercritical fluid carbon dioxide (sc-CO2) was investigated. The actinides U, Np, Pu, and Am were extracted into sc-CO2 modified with TBP from a range of nitric acid concentrations, in the absence of, or in the presence of, a number of traditional reducing and/or complexing agents to demonstrate the separation of these metals from U under sc-CO2 conditions. The separation of U from Pu using sc-CO2 was successful at nitric acid concentrations of less than 3M in the presence of acetohydroxamic acid (AHA) or oxalic acid (OA) to mitigate Pu extraction, and the separation of U from Np was successful at nitric acid concentrations of less than 1M in the presence of AHA, OA, or sodium nitrite to mitigate Np extraction. Americium was not well extracted under any condition studied. PMID:24801893

Quach, Donna L; Mincher, Bruce J; Wai, Chien M

2014-06-15

30

Separation and determination of trace uranium using a double-receptor sandwich supramolecule method based on immobilized salophen and fluorescence labeled oligonucleotide.  

PubMed

A double-receptor sandwich supramolecule method for the separation and determination of trace uranium was proposed in this paper. One receptor is a salophen which can react with uranyl to form a uranyl-salophen complex, and another receptor is an oligonucleotide which can bind uranyl to form oligonucleotide-uranyl-salophen supramolecule. The salophen was immobilized on the surface of silica gel particles and used as the solid phase receptor for separating uranium from solution. The oligonucleotide was labeled with a fluorescent group and used as the labeled receptor for quantitatively analyzing uranium. In the procedure of separation and determination, uranyl ion was first combined with the solid phase receptor and then conjugated with the labeled receptor to form the sandwich-type supramolecule. The labeled receptor in the sandwich supramolecule was then eluted and determined by fluorescence analysis. The experimental results demonstrate that this method has a number of advantages such as high selectivity, excellent pre-concentration capability, high sensitivity, good stability and low cost. Under optimal conditions, the linear range for the detection of uranium is 0.5-30.0 ng mL(-1) with a detection limit of 0.2 ng mL(-1). The proposed method was successfully applied for the separation and determination of uranium in real samples with the recoveries of 95.0-105.5%. PMID:22595437

Wu, Minlong; Liao, Lifu; Zhao, Minmin; Lin, Yingwu; Xiao, Xilin; Nie, Changming

2012-06-01

31

Selective Recovery of Enriched Uranium from Inorganic Wastes  

SciTech Connect

Uranium as U(IV) and U(VI) can be selectively recovered from liquids and sludge containing metal precipitates, inorganic salts, sand and silt fines, debris, other contaminants, and slimes, which are very difficult to de-water. Chemical processes such as fuel manufacturing and uranium mining generate enriched and natural uranium-bearing wastes. This patented Framatome ANP (FANP) uranium recovery process reduces uranium losses, significantly offsets waste disposal costs, produces a solid waste that meets mixed-waste disposal requirements, and does not generate metal-contaminated liquids. At the head end of the process is a floating dredge that retrieves liquids, sludge, and slimes in the form of a slurry directly from the floor of a lined surface impoundment (lagoon). The slurry is transferred to and mixed in a feed tank with a turbine mixer and re-circulated to further break down the particles and enhance dissolution of uranium. This process uses direct steam injection and sodium hypochlorite addition to oxidize and dissolves any U(IV). Cellulose is added as a non-reactive filter aid to help filter slimes by giving body to the slurry. The slurry is pumped into a large recessed-chamber filter press then de-watered by a pressure cycle-controlled double-diaphragm pump. U(VI) captured in the filtrate from this process is then precipitated by conversion to U(IV) in another Framatome ANP-patented process which uses a strong reducing agent to crystallize and settle the U(IV) product. The product is then dewatered in a small filter press. To-date, over 3,000 Kgs of U at 3% U-235 enrichment were recovered from a 8100 m2 hypalon-lined surface impoundment which contained about 10,220 m3 of liquids and about 757 m3 of sludge. A total of 2,175 drums (0.208 m3 or 55 gallon each) of solid mixed-wastes have been packaged, shipped, and disposed. In addition, 9463 m3 of low-U liquids at <0.001 KgU/m3 were also further processed and disposed.

Kimura, R. T.

2003-02-26

32

Geological and geochemical aspects of uranium deposits. A selected, annotated bibliography. Vol. 1  

Microsoft Academic Search

This bibliography was compiled by selecting 580 references from the Bibliographic Information Data Base of the Department of Energy's (DOE) National Uranium Resource Evaluation (NURE) Program. This data base and five others have been created by the Ecological Sciences Information Center to provide technical computer-retrievable data on various aspects of the nation's uranium resources. All fields of uranium geology are

M. B. White; P. A. Garland

1977-01-01

33

Mineralogy and uranium geochemistry of selected volcaniclastic sediments in the western US - an exploration model  

Microsoft Academic Search

This work describes uranium geochemistry of diagenetically altered volcaniclastic sediments from parts of the western US. Geochemical criteria based on analysis of selected volcaniclastic samples are found to be useful in recognizing functional uranium source rocks and act as a frame work and guide for future exploration for uranium in new areas. Comparison of the chemical composition of samples from

Orajaka

1981-01-01

34

Uranium and thorium sequential separation from norm samples by using a SIA system.  

PubMed

This study presents a sequential radiochemical separation method for uranium and thorium isotopes using a novel Sequential Injection Analysis (SIA) system with an extraction chromatographic resin (UTEVA). After the separation, uranium and thorium isotopes have been quantified by using alpha-particle spectrometry. The developed method has been tested by analyzing an intercomparison sample (phosphogypsum sample) from International Atomic Energy Agency (IAEA) with better recoveries for uranium and thorium than the obtained by using a classical method (93% for uranium using the new methodology and 82% with the classical method, and in the case of thorium the recoveries were 70% for the semi-automated method and 60% for the classical strategy). Afterwards, the method was successfully applied to different Naturally Occurring Radioactive Material (NORM) samples, in particular sludge samples taken from a drinking water treatment plant (DWTP) and also sediment samples taken from an area of influence of the dicalcium phosphate (DCP) factory located close to the Ebro river reservoir in Flix (Catalonia). The obtained results have also been compared with the obtained by the classical method and from that comparison it has been demonstrated that the presented strategy is a good alternative to existing methods offering some advantages as minimization of sample handling, reduction of solvents volume and also an important reduction of the time per analysis. PMID:24172603

Mola, M; Nieto, A; Peñalver, A; Borrull, F; Aguilar, C

2014-01-01

35

Engineering High-Fidelity Residue Separations for Selective Harvest  

SciTech Connect

Composition and pretreatment studies of corn stover and wheat stover anatomical fractions clearly show that some corn and wheat stover anatomical fractions are of higher value than others as a biofeedstock. This premise, along with soil sustainability and erosion control concerns, provides the motivation for the selective harvest concept for separating and collecting the higher value residue fractions in a combine during grain harvest. This study recognizes the analysis of anatomical fractions as theoretical feedstock quality targets, but not as practical targets for developing selective harvest technologies. Rather, practical quality targets were established that identified the residue separation requirements of a selective harvest combine. Data are presented that shows that a current grain combine is not capable of achieving the fidelity of residue fractionation established by the performance targets. However, using a virtual engineering approach, based on an understanding of the fluid dynamics of the air stream separation, the separation fidelity can be significantly improved without significant changes to the harvester design. A virtual engineering model of a grain combine was developed and used to perform simulations of the residue separator performance. The engineered residue separator was then built into a selective harvest test combine, and tests performed to evaluate the separation fidelity. Field tests were run both with and without the residue separator installed in the test combine, and the chaff and straw residue streams were collected during harvest of Challis soft white spring wheat. The separation fidelity accomplished both with and without the residue separator was quantified by laboratory screening analysis. The screening results showed that the engineered baffle separator did a remarkable job of effecting high-fidelity separation of the straw and chaff residue streams, improving the chaff stream purity and increasing the straw stream yield.

Kevin L. Kenney; Christopher T. Wright; Reed L. Hoskinson; J. Rochard Hess; David J. Muth, Jr.

2006-07-01

36

Methods for selective functionalization and separation of carbon nanotubes  

NASA Technical Reports Server (NTRS)

The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H (Inventor); Smalley, Richard E. (Inventor); Marek, legal representative, Irene Marie (Inventor)

2011-01-01

37

Highly Selective Separation of DNA Fragments Using Optically Directed Transport  

SciTech Connect

We present a design that allows selective separation of biomolecules of a particular size without performing complete separation of the sample by size. By focusing a laser beam onto a photoelectrode in contact with an electrolyte medium, a highly localized and optically controlled photoelectrophoretic trap is created. Moving the light beam along the photoelectrode consequently moves the trap. We demonstrate that by manipulating the speed of the photoelectrophoretic trap biomolecules of a particular size can be selectively separated from the mixture. We achieve a qualitative agreement between our experimental results and numerical simulations.

Braiman, Avital [ORNL; Rudakov, Fedor M [ORNL; Thundat, Thomas George [ORNL

2010-01-01

38

Application of diode lasers to the isotopically selective determination of uranium in oxides by optogalvanic spectroscopy  

SciTech Connect

We have observed isotopically selective diode laser-excited optogalvanic effects in uranium at 778.42 and 776.19 nm. The samples were natural abundance uranium oxide, as well as depleted (0.3% {sup 235}U), natural (0.7% {sup 235}U) and enriched (9.75% {sup 235}U) uranium metal or powders. The measurements were carried out in a demountable-cathode glow discharge cell. Preliminary evaluations of precision for uranium isotopic ratios measured using this technique suggest that it should have broad analytical applications for uranium and other amenable actinides or lanthanides.

Young, J.P.; Barshick, C.M.; Shaw, R.W.; Ramsey, J.M.

1994-09-01

39

Selective separation of vanadium from molybdenum by electrochemical ion exchange  

Microsoft Academic Search

This paper presents the results of work on the selective electrochemical elution of vanadium co-adsorbed with molybdenum on Amberlite IRA 94S resin. A three-compartment cell equipped with an RVC (Reticulated Vitreous Carbon) cathode mixed with ion exchange resin and two Ti–Pt anodes separated by a Daramic diaphragm was used. In the process, the pentavalent vanadyl anion is selectively desorbed with

P Henry; A Van Lierde

1998-01-01

40

Studies on stannic selenoarsenate. II. Separation of uranium from numerous metal ions  

SciTech Connect

Stannic selenoarsenate has been synthesized by adding 0.05 M sodium selenite and 0.05 M sodium arsenate to a 0.05 M solution of stannic chloride in a volume ratio of 1:1:1 at pH 1. A tentative structure has been proposed on the basis of chemical composition, pH titrations, and infrared and thermogravimetric analyses. Distribution coefficients of several metal ions have been studied in hydrochloric acid, citric acid, ammonium citrate-citric acid, and water-dioxane systems. The unusual adsorption behavior or uranium has been utilized for its quantitative separation from several metal ions.

Nabi, S.A.; Siddiqi, Z.M.; Rao, R.A.K.

1982-12-01

41

Site selection and design options for uranium mine waste and plant tailings  

Microsoft Academic Search

Synopsis Intense public concern regarding the environmental and health effects of uranium tailings has forced a re-evaluation of past disposal practices. Consequently, site selection and design methods for uranium tailings have undergone considerable change and development in recent years. While South African tailings-management technology has contributed significantly to these developments, its public and regulatory review is not, as yet, as

Steffen Robertson

42

The selective use of thorium and heterogeneity in uranium-efficient pressurized water reactors  

E-print Network

Systematic procedures have been developed and applied to assess the uranium utilization potential of a broad range of options involving the selective use of thorium in Pressurized Water Reactors (PWRs) operating on the ...

Kamal, Altamash

1982-01-01

43

New chromatographic materials for the separation and concentration of uranium from environmental matrices  

SciTech Connect

Extraction chromatography, in which an inert support is impregnated with an extractant solution to form a chromatographic resin, combines the specificity of extraction with the ease of operation of an ion exchange column, thereby overcoming the principal drawbacks of the two methods when used alone. Previous work in this laboratory on the design of selective extractants for use in nuclear fuel reprocessing and in nuclear waste treatment has led to the development of several new phosphorus-based neutral organic extractants. In this report, we examine the use of two of these materials as stationary phases in extraction chromatography for the isolation of uranium from environmental samples. 2 refs., 2 figs., 1 tab.

Horwitz, E.P.; Dietz, M.L.; Chiarizia, R.; Diamond, H.

1991-01-01

44

(1) Selective separation and solidification of radioactive nuclides by zeolites  

NASA Astrophysics Data System (ADS)

Massive tsunami generated by the Great East Japan Earthquake attacked the Fukushima Daiichi Nuclear Power Plant and caused the nuclear accident of level 7 to overturn the safety myth of the nuclear power generation. The domestic worst accident does not yet reach the convergence, and many inhabitants around the power plant are forced to double pains of earthquake disaster and nuclear accident. Large amounts of high-activity-level water over 200,000 tons are accumulated on the basement floor of each turbine building, which is a serious obstacle to take measures for the nuclear accident. For the decontamination of high-activity-level water containing seawater, the inorganic ion-exchangers having high selectivity are effective especially for the selective removal of radioactive Cs. On the other hand, radioactive Cs and I released into the atmosphere from the power plant spread widely around Fukushima prefecture, and the decontamination of rainwater and soil become the urgent problem. At present, passing about four months after nuclear accident, the radioactive nuclides of 137Cs and 134Cs are mainly contained in the high-activity-level water and the selective adsorbents for radioactive Cs play an important part in the decontamination. Since the construction of original decontamination system is an urgent necessity, selective separation methods using inorganic ion-exchangers are greatly expected. From the viewpoint of cost efficiency and high Cs-selectivity, natural zeolites are effective for the decontamination of radioactive Cs. This special issue deals with the selective separation and solidification of radioactive Cs and Sr using zeolites.

Mimura, Hitoshi; Sato, Nobuaki; Kirishima, Akira

45

Separation Of Uranium And Plutonium Isotopes For Measurement By Multi Collector Inductively Coupled Plasma Mass Spectroscopy  

SciTech Connect

Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with {sup 233}U and {sup 242}Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA{reg_sign} column coupled to a UTEVA{reg_sign} column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of {sup 234}U/{sup 235}U, {sup 238}U/{sup 235}U, {sup 236}U/{sup 235}U, and {sup 240}Pu/{sup 239}Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment.

Martinelli, R E; Hamilton, T F; Williams, R W; Kehl, S R

2009-03-29

46

Sequential separation of lanthanides, thorium and uranium using novel solid phase extraction method from high acidic nuclear wastes.  

PubMed

A novel grafted polymer for selective extraction and sequential separation of lanthanides, thorium and uranium from high acidic wastes has been developed by grafting Merrifield chloromethylated (MCM) resin with octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) (MCM-CMPO). The grafting process is well characterized using FT-IR spectroscopy, (31)P and (13)C CPMAS (cross-polarized magic angle spin) NMR spectroscopy and CHNPS elemental analysis. The influence of various physico-chemical parameters during metal ion extraction by the resin phase are studied and optimized by both static and dynamic methods. The resin shows very high sorption capacity values of 0.960mmolg(-1) for U(VI), 0.984mmolg(-1) for Th(IV), 0.488mmolg(-1) for La(III) and 0.502mmolg(-1) for Nd(III) under optimum HNO(3) medium, respectively. The grafted polymer shows faster rate exchange kinetics (<5min is sufficient for 50% extraction) and greater preconcentration ability, with reusability exceeding 20 cycles. During desorption process, sequential separation of the analytes is possible with varying eluting agents. The developed grafted resin has been successfully applied in extracting Th(IV) from high matrix monazite sand, U(VI) and Th(IV) from simulated nuclear spent fuel mixtures. All the analytical data is based on triplicate analysis and measurements are within 3.5% rsd reflecting the reproducibility and reliability of the developed method. PMID:17178189

Kesava Raju, Ch Siva; Subramanian, M S

2007-06-25

47

Process for producing enriched uranium having a .sup.235 U content of at least 4 wt. % via combination of a gaseous diffusion process and an atomic vapor laser isotope separation process to eliminate uranium hexafluoride tails storage  

DOEpatents

An uranium enrichment process capable of producing an enriched uranium, having a .sup.235 U content greater than about 4 wt. %, is disclosed which will consume less energy and produce metallic uranium tails having a lower .sup.235 U content than the tails normally produced in a gaseous diffusion separation process and, therefore, eliminate UF.sub.6 tails storage and sharply reduce fluorine use. The uranium enrichment process comprises feeding metallic uranium into an atomic vapor laser isotope separation process to produce an enriched metallic uranium isotopic mixture having a .sup.235 U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % .sup.235 U; fluorinating this enriched metallic uranium isotopic mixture to form UF.sub.6 ; processing the resultant isotopic mixture of UF.sub.6 in a gaseous diffusion process to produce a final enriched uranium product having a .sup.235 U content of at least 4 wt. %, and up to 93.5 wt. % or higher, of the total uranium content of the product, and a low .sup.235 U content UF.sub.6 having a .sup.235 U content of about 0.71 wt. % of the total uranium content of the low .sup.235 U content UF.sub.6 ; and converting this low .sup.235 U content UF.sub.6 to metallic uranium for recycle to the atomic vapor laser isotope separation process.

Horton, James A. (Livermore, CA); Hayden, Jr., Howard W. (Oakridge, TN)

1995-01-01

48

Selective leaching of uranium from uranium-contaminated soils: Progress report 1  

SciTech Connect

Three soils and a sediment contaminated with uranium were used to determine the effectiveness of sodium carbonate and citric acid leaching to decontaminated or remove uranium to acceptable regulatory levels. Two of the soils were surface soils from the DOE facility formerly called the Feed Materials Production Center (FMPC) at Fernald, Ohio. This facility is presently called the Femald Environmental Management Project (FEMP). Carbonate extractions generally removed from 70 to 90% of the uranium from the Fernald storage pad soil. Uranium was slightly more difficult to extract from the Fernald incinerator and the Y-12 landfarm soils. Very small amounts of uranium could be extracted from the storm sewer sediment. Extraction with carbonate at high solution-to-soil ratios were as effective as extractions at low solution-to-soil ratios, indicating attrition by the paddle mixer was not significantly different than that provided in a rotary extractor. Also, pretreatments such as milling or pulverizing the soil sample did not appear to increase extraction efficiency when carbonate extractions were carried out at elevated temperatures (60[degree]C) or long extraction times (23 h). Adding KMnO[sub 4] in the carbonate extraction appeared to increase extraction efficiency from the Fernald incinerator soil but not the Fernald storage pad soil. The most effective leaching rates (> 90 % from both Fernald soils) were obtained using a citrate/dithionite extraction procedure designed to remove amorphous (noncrystalline) iron/aluminum sesquioxides from surfaces of clay minerals. Citric acid also proved to be a very good extractant for uranium.

Francis, C.W.; Mattus, A.J.; Farr, L.L.; Elless, M.P.; Lee, S.Y.

1993-02-01

49

Determination of uranium and rare-earth metals separation coefficients in LiCl KCl melt by electrochemical transient techniques  

NASA Astrophysics Data System (ADS)

The main step in the pyrometallurgical process of spent nuclear fuel recycling is a molten salt electrorefining. The knowledge of separation coefficients of actinides (U, Np, Pu and Am) and rare-earth metals (Y, La, Ce, Nd and Gd) is very important for this step. Usually the separation coefficients are evaluated from the formal standard potentials of metals in melts containing their own ions, values obtained by potentiometric method. Electrochemical experiments were carried out at 723-823 K in order to estimate separation coefficients in LiCl-KCl eutectic melt containing uranium and lanthanum trichlorides. It was shown that for the calculation of uranium and lanthanum separation coefficients it is necessary to determine the voltammetric peak potentials of U(III) and La(III), their concentration in the melt and the kinetic parameters relating to U(III) discharge such as transfer and diffusion coefficients, and standard rate constants of charge transfer.

Kuznetsov, S. A.; Hayashi, H.; Minato, K.; Gaune-Escard, M.

2005-09-01

50

Anion Separation by Selective Crystallization of Metal-Organic-Frameworks  

SciTech Connect

A novel approach for the separation of anions from aqueous mixtures was demonstrated, which involves their selective crystallization with metal-organic frameworks (MOFs) containing urea functional groups. Self-assembly of Zn{sup 2+} with the N,N{prime}-bis(m-pyridyl)urea (BPU) linker results in the formation of one-dimensional MOFs including various anions for charge balance, which interact to different extents with the zinc nodes and the urea hydrogen-bonding groups, depending on their coordinating abilities. Thus, Cl{sup -}, Br{sup -}, I{sup -}, and SO{sub 4}{sup 2-}, in the presence of BPU and Zn{sup 2+}, form MOFs from water, in which the anions coordinate the zinc and are hydrogen-bonded to the urea groups, whereas NO{sub 3}{sup -} and ClO{sub 4}{sup -} anions either do not form MOFs or form water-soluble discrete coordination complexes under the same conditions. X-ray diffraction, FTIR, and elemental analysis of the coordination polymers precipitated from aqueous mixtures containing equivalent amounts of these anions indicated total exclusion of the oxoanions and selective crystallization of the halides in the form of solid solutions with the general composition ZnCl{sub x}Br{sub y}I{sub z} {center_dot} BPU (x + y + z = 2), with an anti-Hofmeister selectivity. The concomitant inclusion of the halides in the same structural frameworks facilitates the rationalization of the observed selectivity on the basis of the diminishing interactions with the zinc and urea acidic centers in the MOFs when going from Cl{sup -} to I{sup -}, which correlates with decreasing anionic charge density in the same order. The overall crystal packing efficiency of the coordination frameworks, which ultimately determines their solubility, also plays an important role in the anion crystallization selectivity under thermodynamic equilibration.

Custelcean, Radu [ORNL

2006-01-01

51

Distribution of uranium and some selected trace metals in human scalp hair from Balkans.  

PubMed

The possible consequences of the use of depleted uranium (DU) used in Balkan conflicts in 1995 and 1999 for the people and the environment of this reason need attention. The heavy metal content in human hair may serve as a good indicator of dietary, environmental and occupational exposures to the metal compounds. The present work summarises the distribution of uranium and some selected trace metals such as Mn, Ni, Cu, Zn, Sr, Cd and Cs in the scalp hair of inhabitants from Balkans exposed to DU directly and indirectly, i.e. Han Pijesak, Bratoselce and Gornja Stubla areas. Except U and Cs, all other metals were compared with the worldwide reported values of occupationally unexposed persons. Uranium concentrations show a wide variation ranging from 0.9 ± 0.05 to 449 ± 12 µg kg(-1). Although hair samples were collected from Balkan conflict zones, uranium isotopic measurement ((235)U/(238)U) shows a natural origin rather than DU. PMID:22940792

Zunic, Z S; Tokonami, S; Mishra, S; Arae, H; Kritsananuwat, R; Sahoo, S K

2012-11-01

52

Procedure and Device for the Separation of an Isotope by Selective Ionization.  

National Technical Information Service (NTIS)

A procedure for the separation of isotopes by selective ionization and which efficiently uses an isotope source is described. A promising technique for higher yield separation of the exp 235 U isotope includes selective ionization of this isotope in urani...

A. Kantrowitz

1975-01-01

53

Application of extraction chromatography to the separation of thorium and uranium dissolved in a solution of high salt concentration  

Microsoft Academic Search

Extraction chromatography with commercially available UTEVA resin (for uranium and tetravalent actinide) was applied for the separation of Th and U from control solutions prepared from a multi-element control solution and from sample solutions of solidified simulated waste. Thorium and U in control solutions with 1–5mol\\/dm3 HNO3 were extracted with UTEVA resin and recovered with a solution containing 0.1mol\\/dm3 HNO3

Asako Fujiwara; Yutaka Kameo; Akiko Hoshi; Tomoko Haraga; Mikio Nakashima

2007-01-01

54

A Bayesian Nonlinear Source Separation Method for Smart Ion-selective Electrode Arrays  

E-print Network

1 A Bayesian Nonlinear Source Separation Method for Smart Ion-selective Electrode Arrays Leonardo T--Potentiometry with ion-selective electrodes (ISEs) provides a simple and cheap approach for estimating ionic activities--Blind source separation, ion-selective electrode, chemical sensor array, Bayesian approach. I. INTRODUCTION ION-selective

Paris-Sud XI, Université de

55

Uranium  

SciTech Connect

The two important oxidation states for uranium in natural environments are 4+ and 6+. Compounds containing quadrivalent uranium are insoluble in mildly acidic to alkaline conditions; whereas, those containing the linearly uranyl moiety (O=U=O)2+, are highly soluble and mobile. In solution, UO22+ forms soluble complexes with carbonate, oxalate, and hydroxide; UO22+ is also highly susceptible to adsorption either by organic matter, Fe oxyhydroxides, or precipitation with various anions, such as silicate, vanadate, arsenate, and phosphate. In ground water systems U(VI) is reduced to U(IV) if an effective reductant is present, such as H2S. Other reducing agents may be fossil plants, methane, and transported humic material. Uranium minerals display an extraordinary range structural and chemical variability, resulting from the different chemical conditions under which U minerals are formed.

Grenthe, Ingmar; Buck, Edgar C.; Drozdynski, J.; Fujino, T.; Albrecht-Schmitt, Thomas; Wolf, Steven F.

2006-07-31

56

Uranium*  

NASA Astrophysics Data System (ADS)

Uranium compounds have been used as colorants since Roman times (Caley, 1948). Uranium was discovered as a chemical element in a pitchblende specimen by Martin Heinrich Klaproth, who published the results of his work in 1789. Pitchblende is an impure uranium oxide, consisting partly of the most reduced oxide uraninite (UO2) and partly of U3O8. Earlier mineralogists had considered this mineral to be a complex oxide of iron and tungsten or of iron and zinc, but Klaproth showed by dissolving it partially in strong acid that the solutions yielded precipitates that were different from those of known elements. Therefore he concluded that it contained a new element (Mellor, 1932); he named it after the planet Uranus, which had been discovered in 1781 by William Herschel, who named it after the ancient Greek deity of the Heavens.

Grenthe, Ingmar; Dro?d?y?ski, Janusz; Fujino, Takeo; Buck, Edgar C.; Albrecht-Schmitt, Thomas E.; Wolf, Stephen F.

57

Use of zirconium(IV) arsenophosphate columns for cation exchange separation of metal ions interfering in the spectrophotometric determination of uranium with sodium diethyl dithiocarbamate  

SciTech Connect

A simple cation exchange method has been developed for the quantitative separation of uranium from some metal ions which generally interfere in its spectrophotometric determination using sodium diethyl dithiocarbamate as a reagent. The method requires only a single bed operation and enables a satisfactory (Error + or - separation of uranium (UO/sub 2/ (II)) up to 1080 ..mu..g from ten metal ions on a 2 g column of zirconium (IV) arsenophosphate cation exchanger in H(I) form.

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

1985-01-01

58

Molecular dynamics simulation of nanoporous graphene for selective gas separation  

E-print Network

Graphene with sub-nanometer sized pores has the potential to act as a filter for gas separation with considerable efficiency gains compared to traditional technologies. Nanoporous graphene membranes are expected to yield ...

Au, Harold (Harold S.)

2012-01-01

59

A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity.  

PubMed

Here, we report a catalytic beacon sensor for uranyl (UO2(2+)) based on an in vitro-selected UO2(2+)-specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3' quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5' and 3' ends, respectively. The presence of UO2(2+) causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM, and selectivity of >1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of approximately 230 microM. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium. PMID:17284609

Liu, Juewen; Brown, Andrea K; Meng, Xiangli; Cropek, Donald M; Istok, Jonathan D; Watson, David B; Lu, Yi

2007-02-13

60

Selective recovery of uranium and thorium ions from dilute aqueous solutions by animal biopolymers.  

PubMed

Selective actinide ion recovery from dilute, aqueous, multication waste streams is an important problem. The recovery of uranium (U) and thorium (Th) by various animal biopolymers was examined. Of four species of biopolymers tested, a high uptake of uranium and thorium was found in hen eggshell membrane (ESM) and silk proteins, with the maximum uranium and thorium recovery exceeding 98% and 79%, respectively. The uptake of U and Th was significantly affected by the pH of the solution. The optimum pH values were 6 and 3 for the uptake of U and Th, respectively. The effect of temperature differed with the metal. The uptake of U decreased with increasing temperature (30-50 degrees C), whereas the Th uptake increased with increasing temperature. Selective recovery of U and Th from dilute aqueous binary and multimetal solutions was also examined. ESM and silk proteins tested were effective and selective for removing each metal by controlling the pH and temperature of the solution. In multimetal systems, the order of sorption of ESM proteins was preferential: U > Cu > Cd > Mn > Pb > Th > Ni > Co > Zn at pH 6 and Th > U > Cu > Pb > Cd > Mn > Co > Ni = Zn at pH 3. These biopolymers appear to have potential for use in a commercial process for actinide recovery from actinide-containing wastewater. PMID:12019520

Ishikawa, Shin-ichi; Suyama, Kyozo; Arihara, Keizo; Itoh, Makoto

2002-06-01

61

A Catalytic Beacon Sensor for Uranium with Parts-per-Trillion Sensitivity and Millionfold Selectivity  

SciTech Connect

Here, we report a catalytic beacon sensor for uranyl (UO{sub 2}{sup 2+}) based on an in vitro-selected UO{sub 2}{sup 2+}-specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3' quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5' and 3' ends, respectively. The presence of UO{sub 2}{sup 2+} causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM, and selectivity of >1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of {approx}230 {micro}M. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium.

Liu, Juewen [University of Illinois, Urbana-Champaign; Brown, Andrea K. [University of Illinois, Urbana-Champaign; Meng, Xiangli [University of Illinois, Urbana-Champaign; Cropek, Donald M. [Construction Engineering Research Laboratory, Champaign, IL; IstokD., Jonathan [Oregon State University, Corvallis; Watson, David B [ORNL; Liu, Yi [University of Illinois, Urbana-Champaign

2007-01-01

62

Laser isotope separation: Non-uranium applications. (Latest citations from the Searchable Physics Information Notices database). Published Search  

SciTech Connect

The bibliography contains citations concerning research and development of laser isotope separation technology. Applications for boron, hydrogen, nitrogen, potassium, and sulfur are examined. Thermal effects generated by the laser on the separation process, selectivity of dissociation, efficiency evaluations of the separation process, and theoretical investigations into the process are also included. (Contains a minimum of 183 citations and includes a subject term index and title list.)

NONE

1995-01-01

63

Laser isotope separation: Non-uranium applications. (Latest citations from the SPIN (Searchable Physics Information Notices) database). Published Search  

SciTech Connect

The bibliography contains citations concerning research and development of laser isotope separation technology. Applications for boron, hydrogen, nitrogen, potassium, and sulfur are examined. Thermal effects generated by the laser on the separation process, selectivity of dissociation, efficiency evaluations of the separation process, and theoretical investigations into the process are also included. (Contains a minimum of 181 citations and includes a subject term index and title list.)

Not Available

1993-11-01

64

Laser isotope separation: Non-uranium applications. (Latest citations from the Searchable Physics Information Notices database). Published Search  

SciTech Connect

The bibliography contains citations concerning research and development of laser isotope separation technology. Applications for boron, hydrogen, nitrogen, potassium, and sulfur are examined. Thermal effects generated by the laser on the separation process, selectivity of dissociation, efficiency evaluations of the separation process, and theoretical investigations into the process are also included. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1996-01-01

65

Separation of Selected Flavonoids by use of RP?HPLC\\/NP?HPTLC Coupled Methods  

Microsoft Academic Search

Phenolic compounds, such as phenolic acids, flavonoids, flavonoid glycosides, and resveratrol, were chromatographed on thin?layers of silica in various eluent systems. Systems with the highest selectivity were chosen. Also, reversed?phase HPLC systems were optimized for the separation of investigated compounds and most the selective system was applied for the separation of two phenolic extracts – Polygonum avicularis and Polygonum hydropiper.

Miros?aw A. Hawry?; Janusz Makar

2007-01-01

66

Geological and geochemical aspects of uranium deposits. A selected, annotated bibliography  

Microsoft Academic Search

A bibliography of 479 references encompassing the fields of uranium and thorium geochemistry and mineralogy, geology of uranium deposits, uranium mining, and uranium exploration techniques has been compiled by the Ecological Sciences Information Center of Oak Ridge National Laboratory. The bibliography was produced for the National Uranium Resource Evaluation Program, which is funded by the Grand Junction Office of the

P. A. Garland; J. M. Thomas; M. L. Brock; E. W. Daniel

1980-01-01

67

Separation of mixed post-consumer PET–POM–PVC plastic waste using selective flotation  

Microsoft Academic Search

The main objective of this research is to separate a mixed post-consumer engineering plastic waste (PET, POM, and PVC) based on type of plastic using selective flotation separation. Depressing effect of wetting agent and aluminium sulfate on plastic is attributed mainly to the separation. POM is separated from the mixture waste when using 500mg\\/l calcium lignosulfonate as a wetting agent

Thongchai Takoungsakdakun; Sangobtip Pongstabodee

2007-01-01

68

Separation of neptunium, plutonium, americium and curium from uranium with di-(2-ethylhexyl)-phosphoric acid (HDEHP) for radiometric and ICP-MS analysis  

Microsoft Academic Search

The possibility of using di-(2-ethylhexyl)-phosphoric acid (HDEHP) in solvent extraction for the separation of neptunium,\\u000a plutonium, americium and curium from large amounts of uranium was studied. Neptunium, plutonium, americium and curium (as\\u000a well as uranium) were extracted from HNO3, whereafter americium and curium were back-extracted with 5M HNO3. Thereafter was neptunium back-extracted in 1M HNO3 containing hydroxylamine hydronitrate. Finally, plutonium

H. Ramebäck; M. Sk?lberg

1998-01-01

69

Source separation, selective collection and in reactor digestion of biowaste  

Microsoft Academic Search

Biowaste or the organic fraction of domestic waste, for instance kitchen, fruit and garden waste, is collected selectively in several European communities. The complementary fraction is called the dry or non recyclable fraction. A Dutch study reported that 92% of the participants that have a weekly collection service of both fractions (biowaste and non recyclable fraction) and 80% of the

Veerle Gellens; Jan Boelens; Willy Verstraete

1995-01-01

70

Application of ion-exchange separations to determination of trace elements in natural waters-IX: simultaneous isolation and determination of uranium and thorium.  

PubMed

A method is described for the determination of uranium and thorium in samples of natural waters. After acidification with citric acid the water sample is filtered and sodium citrate and ascorbic acid are added. The resulting solution of pH 3 is passed through a 4-g column of Dowex 1 x 8 (citrate form) on which both uranium and thorium are adsorbed as anionic citrate complexes. Thorium is eluted with 8M hydrochloric acid and separated from co-eluted substances by anion-exchange in 8M nitric acid medium on a separate 2-g column of the same resin in the nitrate form. After complete removal of iron by washing with a mixture consisting of IBMK, acetone and 1M hydrochloric acid (1:8:1 v v ) and treatment of the resin with 6M hydrochloric acid, the uranium is eluted from the 4-g column with 1M hydrochloric acid. In the eluate thorium is determined spectrophotometrically (arsenazo III method) while fluorimetry is employed for the assay of uranium. The procedure was used for the determination of uranium and thorium in numerous water samples collected in Austria, including samples of mineral-waters. The results indicate that a simple relationship exists between the uranium and thorium contents of waters which makes it possible to calculate the approximate thorium content of a sample on the basis of its uranium concentration and vice versa. PMID:18961858

Korkisch, J; Krivanec, H

1976-04-01

71

Metal-Organic Frameworks for Highly Selective Separations  

SciTech Connect

This grant was focused on the study of metal-organic frameworks with these specific objectives. (1) To examine the use of MOFs with well-defined open metal sites for binding of gases and small organics. (2) To develop a strategy for producing MOFs that combine large pore size with high surface area for their use in gas adsorption and separation of polycyclic organic compounds. (3) To functionalize MOFs for the storage of inert gases such as methane. A brief outline of our progress towards these objectives is presented here as it forms part of the basis for the ideas to be developed under the present proposal.

Omar M. Yaghi

2009-09-28

72

Separation of rare gases and chiral molecules by selective binding in porous organic cages.  

PubMed

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation. PMID:25038731

Chen, Linjiang; Reiss, Paul S; Chong, Samantha Y; Holden, Daniel; Jelfs, Kim E; Hasell, Tom; Little, Marc A; Kewley, Adam; Briggs, Michael E; Stephenson, Andrew; Thomas, K Mark; Armstrong, Jayne A; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M; Thallapally, Praveen K; Cooper, Andrew I

2014-10-01

73

Separation of rare gases and chiral molecules by selective binding in porous organic cages  

NASA Astrophysics Data System (ADS)

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation.

Chen, Linjiang; Reiss, Paul S.; Chong, Samantha Y.; Holden, Daniel; Jelfs, Kim E.; Hasell, Tom; Little, Marc A.; Kewley, Adam; Briggs, Michael E.; Stephenson, Andrew; Thomas, K. Mark; Armstrong, Jayne A.; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.; Cooper, Andrew I.

2014-10-01

74

Analysis of excursions at selected in situ uranium mines in Wyoming and Texas. [Case studies  

SciTech Connect

Intensive research and development of in situ uranium mining took place in the United States during the 1970s. By the end of the decade, nearly 10% of all uranium production came from in situ mines. Recent poor market conditions, however, forced the closure of all domestic in situ uranium mines. When market conditions improve, domestic in situ mining is expected to make a modest recovery. Successful licensing of future in situ mines will depend to a large extent on the ability to contain the leach solutions (lixiviant) within the ore zone. Uncontrolled movement of lixiviant beyond the ore zone is called an excursion. The industry has demonstrated the capability to reduce, monitor, and control lateral excursions in an ore zone aquifer. On the other hand, vertical excursions of lixiviant migrating into an overlying aquifer through poorly plugged exploration holes continue to plague the industry. This paper summarizes the history of excursions at selected in situ mines in the United States and discusses methodologies for excursion identification and control. The incidence of vertical excursions can be significantly reduced by certifying well field units through field-wide testing of the ore zone aquifer prior to the injection of lixiviant. An overlying aquifer can be effectively monitored for excursions by periodically analyzing fluids in observation wells for nonreactive ionic species common to the lixiviant. These ions would necessarily have low probabilities of naturally exceeding a given concentration, referred to as an upper control limit. A mining unit would require recertification after each vertical excursion.

Staub, W.P.; Williams, R.E.; Anastasi, F.; Hinkle, N.E.; Osiensky, J.; Rogness, D.

1986-06-01

75

Ion-selective Electrode Array based on a Bayesian Nonlinear Source Separation Method  

E-print Network

Ion-selective Electrode Array based on a Bayesian Nonlinear Source Separation Method Leonardo proposal is attested by experiments using artificial and real data. 1 Introduction Ion-selective electrodes 6597, Ecole Centrale Nantes, France Said.Moussaoui@irccyn.ec-nantes.fr Abstract. Ion-selective

Paris-Sud XI, Université de

76

Selective-Tap Blind Signal Processing for Speech Separation  

PubMed Central

In this paper, we propose a new blind multichannel adaptive filtering scheme, which incorporates a partial-updating mechanism in the error gradient of the update equation. The proposed blind processing algorithm operates in the time-domain by updating only a selected portion of the adaptive filters. The algorithm steers all computational resources to filter taps having the largest magnitude gradient components on the error surface. Therefore, it requires only a small number of updates at each iteration and can substantially minimize overall computational complexity. Numerical experiments carried out in realistic blind identification scenarios indicate that the performance of the proposed algorithm is comparable to the performance of its full-update counterpart, but with the added benefit of a highly reduced computational complexity. PMID:19964609

Kokkinakis, Kostas; Loizou, Philipos C.

2010-01-01

77

Preparation and adsorption performance of 5-azacytosine-functionalized hydrothermal carbon for selective solid-phase extraction of uranium.  

PubMed

A new solid-phase extraction adsorbent was prepared by employing a two-step "grafting from" approach to anchor a multidentate N-donor ligand, 5-azacytosine onto hydrothermal carbon (HTC) microspheres for highly selective separation of U(VI) from multi-ion system. Fourier-transform infrared and X-ray photoelectron spectroscopies were used to analyze the chemical structure and properties of resultant HTC-based materials. The adsorption behavior of U(VI) onto the adsorbent was investigated as functions of pH, contact time, ionic strength, temperature, and initial U(VI) concentration using batch adsorption experiments. The U(VI) adsorption was of pH dependent. The adsorption achieved equilibrium within 30 min and followed a pseudo-second-order equation. The adsorption amount of U(VI) increased with raising the temperature from 283.15 to 333.15K. Remarkably, high ionic strength up to 5.0 mol L(-1) NaNO(3) had only slight effect on the adsorption. The maximum U(VI) adsorption capacity reached 408.36 mg g(-1) at 333.15K and pH 4.5. Results from batch experiments in a simulated nuclear industrial effluent, containing 13 co-existing cations including uranyl ion, showed a high adsorption capacity and selectivity of the adsorbent for uranium (0.63 mmol U g(-1), accounting for about 67% of the total adsorption amount). PMID:22918045

Song, Qiang; Ma, Lijian; Liu, Jun; Bai, Chiyao; Geng, Junxia; Wang, Hang; Li, Bo; Wang, Liyue; Li, Shoujian

2012-11-15

78

Plutonium-uranium separation in the Purex process using mixtures of hydroxylamine nitrate and ferrous sulfamate  

SciTech Connect

Laboratory studies, followed by plant operation, established that a mixture of hydroxylamine nitrate (HAN) and ferrous sulfamate (FS) is superior to FS used alone as a reductant for plutonium in the Purex first cycle. FS usage has been reduced by about 70% (from 0.12 to 0.04M) compared to the pre-1978 period. This reduced the volume of neutralized waste due to FS by 194 liters/metric ton of uranium (MTU) processed. The new flowsheet also gives lower plutonium losses to waste and at least comparable fission product decontamination. To achieve satisfactory performance at this low concentration of FS, the acidity in the 1B mixer-settler was reduced by using a split-scrub - a low acid scrub in stage one and a higher acid scrub in stage three - to remove acid from the solvent exiting the 1A centrifugal contactor. 8 references, 14 figures, 1 table.

McKibben, J.M.; Chostner, D.F.; Orebaugh, E.G.

1983-11-01

79

Separation of Bulk Carbon Dioxide-Hydrogen Mixtures by Selective Surface Flow Membrane  

Microsoft Academic Search

The separation performance of carbon dioxide-hydrogen mixtures by a nanoporous carbon membrane called selective surface flow membrane is described. The membrane selectively permeates CO2 from H2 and a H2 enriched gas is produced at the feed gas pressure. Extensive experimental data for the separation using feed gas pressures from 0.24 to 1.13 MPa and CO2 compositions from 5 to 75

M. Paranjape; P. F. Clarke; B. B. Pruden; D. J. Parrillo; C. Thaeron; S. Sircar

1998-01-01

80

Selective aqueous extraction of organics coupled with trapping by membrane separation  

DOEpatents

An improvement to processes for the selective extractation of organic solutes from organic solvents by water-based extractants is disclosed, the improvement comprising coupling various membrane separation processes with the organic extraction process, the membrane separation process being utilized to continuously recycle the water-based extractant and at the same time selectively remove or concentrate organic solute from the water-based extractant.

van Eikeren, Paul (Bend, OR); Brose, Daniel J. (Bend, OR); Ray, Roderick J. (Bend, OR)

1991-01-01

81

Novel Synergistic Agent for Selective Separation of Yttrium from Other Rare Earth Metals  

Microsoft Academic Search

An oil-soluble synergistic agent has been developed for the selective separation of yttrium (Y) from the other rare earth metals. The synergistic agent is a polyaminocarboxylic acid alkylderivative and has interfacial activity like that of surfactants. Separation of yttrium from heavy rare earth metals [erbium (Er) and holmium (Ho)] in the presence of the synergistic agent was carried out with

Terufumi Miyata; Masahiro Goto; Fumiyuki Nakashio

1995-01-01

82

Geological and geochemical aspects of uranium deposits. A selected, annotated bibliography  

SciTech Connect

A bibliography of 479 references encompassing the fields of uranium and thorium geochemistry and mineralogy, geology of uranium deposits, uranium mining, and uranium exploration techniques has been compiled by the Ecological Sciences Information Center of Oak Ridge National Laboratory. The bibliography was produced for the National Uranium Resource Evaluation Program, which is funded by the Grand Junction Office of the Department of Energy. The references contained in the bibliography have been divided into the following eight subject categories: (1) geology of deposits, (2) geochemistry, (3) genesis O deposits, (4) exploration, (5) mineralogy, (6) uranium industry, (7) reserves and resources, and (8) geology of potential uranium-bearing areas. All categories specifically refer to uranium and thorium; the last category contains basic geologic information concerning areas which the Grand Junction Office feels are particularly favorable for uranium deposition. The references are indexed by author, geographic location, quadrangle name, geoformational feature, taxonomic name, and keyword.

Garland, P.A.; Thomas, J.M.; Brock, M.L.; Daniel, E.W. (comps.)

1980-06-01

83

Application of extraction chromatography to the separation of thorium and uranium dissolved in a solution of high salt concentration.  

PubMed

Extraction chromatography with commercially available UTEVA resin (for uranium and tetravalent actinide) was applied for the separation of Th and U from control solutions prepared from a multi-element control solution and from sample solutions of solidified simulated waste. Thorium and U in control solutions with 1-5mol/dm(3) HNO(3) were extracted with UTEVA resin and recovered with a solution containing 0.1mol/dm(3) HNO(3) and 0.05mol/dm(3) oxalic acid to be separated from the other metallic elements. Extraction behavior of U in the sample solutions was similar to that in the control solutions, but extraction of Th was dependent on the concentration of HNO(3). Thorium was extracted from 5mol/dm(3) HNO(3) sample solutions but not from 1mol/dm(3) HNO(3) sample solutions. We conjecture that thorium fluoride formation interferes with extraction of Th. Addition of Al(NO(3))(3) and Fe(NO(3))(3), which have higher stability constant with fluoride ion than Th, does improve extractability of Th from 1mol/dm(3) HNO(3) sample solution. PMID:17161412

Fujiwara, Asako; Kameo, Yutaka; Hoshi, Akiko; Haraga, Tomoko; Nakashima, Mikio

2007-01-26

84

Biomonitoring of environmental pollution by thorium and uranium in selected regions of the Republic of Kazakhstan  

Microsoft Academic Search

Two former uranium mines and a uranium reprocessing factory in the city of Aktau, Kazakhstan, may represent a risk of contaminating the surrounding areas by uranium and its daughter elements. One of the possible fingerprinting tools for studying the environmental contamination is using plant samples, collected in the surroundings of this city in 2007 and 2008. The distribution pattern of

P. Zoriy; P. Ostapczuk; H. Dederichs; J. Höbig; R. Lennartz; M. Zoriy

2010-01-01

85

Analysis of excursions at selected in situ uranium mines in Wyoming and Texas. [Case studies  

Microsoft Academic Search

Intensive research and development of in situ uranium mining took place in the United States during the 1970s. By the end of the decade, nearly 10% of all uranium production came from in situ mines. Recent poor market conditions, however, forced the closure of all domestic in situ uranium mines. When market conditions improve, domestic in situ mining is expected

W. P. Staub; R. E. Williams; F. Anastasi; N. E. Hinkle; J. Osiensky; D. Rogness

1986-01-01

86

Introduction of structural affinity handles as a tool in selective nucleic acid separations  

NASA Technical Reports Server (NTRS)

The method is used for separating nucleic acids and other similar constructs. It involves selective introduction, enhancement, or stabilization of affinity handles such as single-strandedness in the undesired (or desired) nucleic acids as compared to the usual structure (e.g., double-strandedness) of the desired (or undesired) nucleic acids. The undesired (or desired) nucleic acids are separated from the desired (or undesired) nucleic acids due to capture by methods including but not limited to immobilized metal affinity chromatography, immobilized single-stranded DNA binding (SSB) protein, and immobilized oligonucleotides. The invention is useful to: remove contaminating genomic DNA from plasmid DNA; remove genomic DNA from plasmids, BACs, and similar constructs; selectively separate oligonucleotides and similar DNA fragments from their partner strands; purification of aptamers, (deoxy)-ribozymes and other highly structured nucleic acids; Separation of restriction fragments without using agarose gels; manufacture recombinant Taq polymerase or similar products that are sensitive to host genomic DNA contamination; and other applications.

Willson, III, Richard Coale (Inventor); Cano, Luis Antonio (Inventor)

2011-01-01

87

Ultrafiltration of uranyl peroxide nanoclusters for the separation of uranium from aqueous solution.  

PubMed

Uranyl peroxide cluster species were produced in aqueous solution by the treatment of uranyl nitrate with hydrogen peroxide, lithium hydroxide, and potassium chloride. Ultrafiltration of these cluster species using commercial sheet membranes with molecular mass cutoffs of 3, 8, and 20 kDa (based on polyethylene glycol) resulted in U rejection values of 95, 85, and 67% by mass, respectively. Ultrafiltration of untreated uranyl nitrate solutions using these membranes resulted in virtually no rejection of U. These results demonstrate the ability to use the filtration of cluster species as a means for separating U from solutions on the basis of size. Small-angle X-ray scattering, Raman spectroscopy, and electrospray ionization mass spectrometry confirmed the presence of uranyl peroxide cluster species in solution and were used to characterize their size, shape, and dispersity. PMID:24313601

Wylie, Ernest M; Peruski, Kathryn M; Weidman, Jacob L; Phillip, William A; Burns, Peter C

2014-01-01

88

Highly Selective Membranes For The Separation Of Organic Vapors Using Super-Glassy Polymers  

DOEpatents

A process for separating hydrocarbon gases of low boiling point, particularly methane, ethane and ethylene, from nitrogen. The process is performed using a membrane made from a super-glassy material. The gases to be separated are mixed with a condensable gas, such as a C.sub.3+ hydrocarbon. In the presence of the condensable gas, improved selectivity for the low-boiling-point hydrocarbon gas over nitrogen is achieved.

Pinnau, Ingo (Palo Alto, CA); Lokhandwala, Kaaeid (Menlo Park, CA); Nguyen, Phuong (Fremont, CA); Segelke, Scott (Mountain View, CA)

1997-11-18

89

Improvement of the Immunomagnetic Separation Method Selective for Escherichia coli O157 Strains  

PubMed Central

Immunomagnetic separation is a useful enrichment method selective for Escherichia coli O157 cells against non-O157 E. coli cells from a preenrichment culture. However, E. coli cells are adsorbed onto a solid surface nonspecifically. With the conventional immunomagnetic separation method, this nonspecific adsorption interfered with immunomagnetic separation. It was found that this interference could be reduced with a low-ionic-strength solution. When immunomagnetic separation was carried out with this solution, the proportion of E. coli O157 cells to non-O157 E. coli cells increased from 9.6 to 31.4 times compared to the proportion obtained by the conventional immunomagnetic separation method. The effectiveness of this solution was successfully evaluated by the use of E. coli O157-spiked samples. PMID:9435093

Tomoyasu, Takahiro

1998-01-01

90

Highly selective biomechanical separation of cancer cells from leukocytes using microfluidic ratchets and hydrodynamic concentrator  

PubMed Central

The separation of cells based on their biomechanical properties, such as size and deformability, is important in applications such as the identification of circulating tumor cells, where morphological differences can be used to distinguish target cancer cells from contaminant leukocytes. Existing filtration-based separation processes are limited in their selectivity and their ability to extract the separated cells because of clogging in the filter microstructures. We present a cell separation device consisting of a hydrodynamic concentrator and a microfluidic ratchet mechanism operating in tandem. The hydrodynamic concentrator removes the majority of the fluid and a fraction of leukocytes based on size, while the microfluidic ratchet mechanism separates cancer cells from leukocytes based on a combination of size and deformability. The irreversible ratcheting process enables highly selective separation and robust extraction of separated cells. Using cancer cells spiked into leukocyte suspensions, the complete system demonstrated a yield of 97%, while enriching the concentration of target cancer cells 3000 fold relative to the concentration of leukocytes. PMID:24404034

Lin, Bill K.; McFaul, Sarah M.; Jin, Chao; Black, Peter C.; Ma, Hongshen

2013-01-01

91

Synthesis of salicylaldehyde-modified mesoporous silica and its application as a new sorbent for separation, preconcentration and determination of uranium by inductively coupled plasma atomic emission spectrometry.  

PubMed

A new functionalized mesoporous silica (MCM-41) using salicylaldehyde was utilized for the separation, preconcentration and determination of uranium in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace levels of U(VI) were optimized. The preconcentration factor was 100 (1.0 mL of elution for a 100 mL sample volume). The analytical curve was linear in the range 2-1000 microg L(-1) and the detection limit was 0.5 ng mL(-1). The relative standard deviation (R.S.D.) under optimum conditions was 2.5% (n=10). Common coexisting ions did not interfere with the separation and determination of uranium at pH 5. The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be 10mg of uranium per gram of sorbent. The method was applied for the recovery and determination of uranium in different water samples. PMID:17723729

Jamali, Mohammad Reza; Assadi, Yaghoub; Shemirani, Farzaneh; Hosseini, Mohammad Reza Milani; Kozani, Reyhaneh Rahnama; Masteri-Farahani, Majid; Salavati-Niasari, Masoud

2006-10-01

92

Cell Adsorption and Selective Desorption for Separation of Microbial Cells by Using Chitosan-Immobilized Silica  

Microsoft Academic Search

Cell adsorption and selective desorption for separation of microbial cells were conducted by using chitosan- immobilized silica (CIS). When chitosan was immobilized onto silica surfaces with glutaraldehyde, bacterial cells adsorbed well and retained viability. Testing of the adsorption and desorption ability of CIS using various microbes such as Escherichia coli, Aeromonas hydrophila, Pseudomonas aeruginosa, Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus,

Munehiro Kubota; Masayoshi Matsui; Hiroyuki Chiku; Nobuyuki Kasashima; Manabu Shimojoh; Kengo Sakaguchi

2005-01-01

93

The Separation of Beryllium from Selected Elements Using the Dipex Extraction Chromatographic Resin  

Microsoft Academic Search

An extraction chromatographic resin containing the acidic chelating organophosphorus extractant, Dipex, sorbed onto an inert polymeric substrate has been evaluated for the separation of beryllium from a wide range of elements. The elements selected comprise those which can interfere with the determination of beryllium by inductively coupled plasma?atomic emission spectroscopy (ICP?AES) and matrix elements which commonly occur in environmental and

E. Philip Horwitz; Daniel R. McAlister

2005-01-01

94

Development of an electrically switched ion exchange process for selective ion separations  

Microsoft Academic Search

The electrically switched ion exchange (ESIX) process, being developed at Pacific Northwest National Laboratory, provides an alternative separation method to selectively remove ions from process and waste streams. In the ESIX process, in which an electroactive ion exchange film is deposited onto a high surface area elecrotrode, uptake and elution are controlled directly by modulating the electrochemical potential of the

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

1999-01-01

95

Modeling the selectivity of activated carbons for efficient separation of hydrogen and carbon dioxide  

E-print Network

the separation of hydrogen and carbon dioxide via adsorption in activated carbons. In the simulations, both hydrogen and carbon dioxide molecules are modeled as Lennard-Jones spheres, and the activated carbons essentially no preference over the two gases and the selectivity of carbon dioxide relative to hydrogen falls

Wu, Jianzhong

96

Synthesis of salicylaldehyde-modified mesoporous silica and its application as a new sorbent for separation, preconcentration and determination of uranium by inductively coupled plasma atomic emission spectrometry  

Microsoft Academic Search

A new functionalized mesoporous silica (MCM-41) using salicylaldehyde was utilized for the separation, preconcentration and determination of uranium in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES).Experimental conditions for effective adsorption of trace levels of U(VI) were optimized. The preconcentration factor was 100 (1.0mL of elution for a 100mL sample volume). The analytical curve was linear in the

Mohammad Reza Jamali; Yaghoub Assadi; Farzaneh Shemirani; Mohammad Reza Milani Hosseini; Reyhaneh Rahnama Kozani; Majid Masteri-Farahani; Masoud Salavati-Niasari

2006-01-01

97

Application of Blind Source Separation Methods to Ion-selective Electrode Arrays in Flow-injection Analysis  

E-print Network

1 Application of Blind Source Separation Methods to Ion-selective Electrode Arrays in Flow, the interference problem typical of ion-selective electrodes can be dealt with via smart arrays adjusted by blind Terms--Chemical sensor arrays, blind source separation, ion-selective electrodes, signal processing. I

Boyer, Edmond

98

Cell adsorption and selective desorption for separation of microbial cells by using chitosan-immobilized silica.  

PubMed

Cell adsorption and selective desorption for separation of microbial cells were conducted by using chitosan-immobilized silica (CIS). When chitosan was immobilized onto silica surfaces with glutaraldehyde, bacterial cells adsorbed well and retained viability. Testing of the adsorption and desorption ability of CIS using various microbes such as Escherichia coli, Aeromonas hydrophila, Pseudomonas aeruginosa, Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Lactobacillus casei, Streptococcus mutans, Streptococcus sobrinus, Streptococcus salivarius, Saccharomyces cerevisiae, Saccharomyces ludwigii, and Schizosaccharomyces pombe revealed that most microbes could be adsorbed and selectively desorbed under different conditions. In particular, recovery was improved when L-cysteine was added. A mixture of two bacterial strains adsorbed onto CIS could also be successfully separated by use of specific solutions for each strain. Most of the desorbed cells were alive. Thus, quantitative and selective fractionation of cells is readily achievable by employing chitosan, a known antibacterial material. PMID:16332887

Kubota, Munehiro; Matsui, Masayoshi; Chiku, Hiroyuki; Kasashima, Nobuyuki; Shimojoh, Manabu; Sakaguchi, Kengo

2005-12-01

99

Highly Selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications  

SciTech Connect

Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective H{sub 2} separation from other light gases (CO{sub 2}, CH{sub 4}, CO). However, zeolite membranes have not been successful for H{sub 2} separation from light gases because the zeolite pores are either too big or the membranes have a large number of defects. The objective of this study is to develop zeolite membranes that are more suitable for H{sub 2} separation. In an effort to tune the size of zeolite pores and/or to decrease the number of defects, medium-pore zeolite B-ZSM-5 (MFI) membranes were synthesized and silylated. Silylation on B-ZSM-5 crystals reduced MFI-zeolite pore volume, but had little effect on CO{sub 2} and CH{sub 4} adsorption. Silylation on B-ZSM-5 membranes increased H{sub 2} selectivity both in single component and in mixtures with CO{sub 2}CO{sub 2}, CH{sub 4}, or N2. Single gas and binary mixtures of H{sub 2}/CO{sub 2} and H{sub 2}/CH{sub 4} were separated through silylated B-ZSM-5 membranes at feed pressures up to 1.7 MPa and temperatures up to 773 K. For one BZSM-5 membrane after silylation, the H2/CO{sub 2} separation selectivity at 473 K increased from 1.4 to 37, whereas the H{sub 2}/CH{sub 4} separation selectivity increased from 1.6 to 33. Hydrogen permeance through a silylated B-ZSM-5 membrane was activated, but the CO{sub 2} and CH4 permeances decreased slightly with temperature in both single gas and in mixtures. Therefore, the H{sub 2} permeance and H{sub 2}/CO{sub 2} and H{sup 2} /CH{sub 4} separation selectivities increased with temperature. At 673 K, the H2 permeance was 1.0x10-7 molxm-2xs-1xPa-1, and the H{sub 2}/CO{sub 2} separation selectivity was 47. Above 673 K, the silylated membrane catalyzed reverse water gas shift reaction and still separated H{sub 2} with high selectivity; and it was thermally stable. However, silylation decreased H{sub 2} permeance more than one order of magnitude. The H{sub 2} separation performance of the silylated B-ZSM-5 membranes depended on the initial membrane quality and acidity, as well as the silane precursors. Increasing the membrane feed pressure also increased the H{sub 2} flux and the H{sub 2} mole fraction in the permeate stream for both mixtures. Another approach used in this study is optimizing the synthesis of small-pore SAPO-34 (CHA) membranes and/or modifying SAPO-34 membranes by silylation or ion exchange. For SAPO-34 membranes, strong CO{sub 2} adsorption inhibited H{sub 2} adsorption and decreased H2 permeances, especially at low temperatures. At 253 K, CO{sub 2}/H{sub 2} separation selectivities of a SAPO-34 membrane were greater than 100 with CO{sub 2} permeances of about 3 x 10-8 mol m-2 s-1 Pa-1. The high reverse-selectivity of the SAPO-34 membranes can minimize H{sub 2} recompression because H{sub 2} remained in the retentate stream at a higher pressure. The CO{sub 2}/H{sub 2} separation selectivity exhibited a maximum with CO{sub 2} feed concentration possibly caused by a maximum in the CO{sub 2}/H{sub 2} sorption selectivity with increased CO{sub 2} partial pressure. The SAPO-34 membrane separated H{sub 2} from CH{sub 4} because CH{sub 4} is close to the SAPO-34 pore size so its diffusivity is much lower than the H{sup 2} diffusivity. The H{sub 2}/CH{sub 4} separation selectivity was almost independent of temperature, pressure, and feed composition. Silylation on SAPO-34 membranes increased H{sup 2}/CH{sub 4} and CO{sub 2}/CH{sub 4} selectivities but did not increase H{sub 2}/CO{sub 2} and H{sub 2}/N{sub 2} selectivities because silylation only blocked defects in SAPO-34 membranes. Hydr

Mei Hong; Richard D. Noble; John L. Falconer

2006-09-24

100

Ultrathin self-assembled anionic polymer membranes for superfast size-selective separation  

NASA Astrophysics Data System (ADS)

Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles.Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles. Electronic supplementary information (ESI) available: Synthesis and characterization of SPEK-C; effect of the sulfonation degree on membrane formation; structure and properties of the self-assembled membranes; separation of cyt.c by the self-assembled membranes; size-selective separation of gold nanoparticles by the self-assembled membranes; comparison with commercial flat sheet ultrafiltration membranes. See DOI: 10.1039/c3nr03362g

Deng, Chao; Zhang, Qiu Gen; Han, Guang Lu; Gong, Yi; Zhu, Ai Mei; Liu, Qing Lin

2013-10-01

101

Adsorbate shape selectivity: Separation of the HF/134a azeotrope over carbogenic molecular sieve  

SciTech Connect

Experimental evidence is provided for adsorptive shape selectivity in the separation of the azeotrope between HF and 1,1,1,2-tetrafluoroethane (134a) over pyrolyzed poly(furfuryl alcohol)-derived carbogenic molecular sieve (PPFA-CMS). The separation can be accomplished over coconut charcoal or Carbosieve G on the basis of the differences in the extent of equilibrium adsorption of HF and 134a. On these adsorbents 134a is more strongly bound than HF, thus it elutes much more slowly from the bed. The heat of adsorption for 134a in the vicinity of 200 C on Carbosieve G is {approximately}8.8 kcal/mol. In contrast, when the same azeotropic mixture is separated over PPFA-CMS prepared at 500 C, 134a is not adsorbed. As a result 134a elutes from the bed first, followed by HF. The reversal is brought about by the narrower pore size and pore size distribution of the PPFA-CMS versus that for Carbosieve G. Thus the separation over PPFA-CMS is an example of adsorbate shape selectivity and represents a limiting case of kinetic separation.

Hong, A.; Mariwala, R.K.; Kane, M.S.; Foley, H.C. [Univ. of Delaware, Nework, DE (United States)

1995-03-01

102

Large-Flow-Area Flow-Selective Liquid/Gas Separator  

NASA Technical Reports Server (NTRS)

This liquid/gas separator provides the basis for a first stage of a fuel cell product water/oxygen gas phase separator. It can separate liquid and gas in bulk in multiple gravity environments. The system separates fuel cell product water entrained with circulating oxygen gas from the outlet of a fuel cell stack before allowing the gas to return to the fuel cell stack inlet. Additional makeup oxygen gas is added either before or after the separator to account for the gas consumed in the fuel cell power plant. A large volume is provided upstream of porous material in the separator to allow for the collection of water that does not exit the separator with the outgoing oxygen gas. The water then can be removed as it continues to collect, so that the accumulation of water does not impede the separating action of the device. The system is designed with a series of tubes of the porous material configured into a shell-and-tube heat exchanger configuration. The two-phase fluid stream to be separated enters the shell-side portion of the device. Gas flows to the center passages of the tubes through the porous material and is then routed to a common volume at the end of the tubes by simple pressure difference from a pumping device. Gas flows through the porous material of the tubes with greater ease as a function of the ratio of the dynamic viscosity of the water and gas. By careful selection of the dimensions of the tubes (wall thickness, porosity, diameter, length of the tubes, number of the tubes, and tube-to-tube spacing in the shell volume) a suitable design can be made to match the magnitude of water and gas flow, developed pressures from the oxygen reactant pumping device, and required residual water inventory for the shellside volume.

Vasquez, Arturo; Bradley, Karla F.

2010-01-01

103

Selective Separation of Rare Earth Metals by Solvent Extraction in the Presence of New Hydrophilic Chelating Polymers Functionalized with Ethylenediaminetetraacetic Acid. II. Separation Properties by Solvent Extraction  

Microsoft Academic Search

The selective separation of rare earth metals by solvent extraction including chelating polymers in the aqueous phase was investigated. The chelating polymers were synthesized in this laboratory by introducing ethylenediaminetetraacetic acid (EDTA) onto water-soluble polyallylamine. The highest selectivity obtained for the Y\\/Er separation system was 14.7, which was much higher than that in conventional solvent extraction (about 1.4) and also

HIDETO MATSUYAMA; YOSHIKAZU MIYAMOTO; MASAAKI TERAMOTO; MASAHIRO GOTO; FUMIYUKI NAKASHIO

1996-01-01

104

Design and Development of Selective Extractants for An/Ln Separations  

SciTech Connect

This study has succeeded in further developing phosphinoylmethyl pyridine compounds as selective recognition and separations agents for trivalent lanthanide and actinide ions present in nuclear materials. The parameters for efficient separations have been further elucidated and factors important to further development have been identified. Further development will lead to optimal extractant design for effective actinide ion partitioning under process practical conditions. The primary objective of the project involved the design, synthesis, and characterization of the extraction performance of 2,6-bis(phosphinomethyl)pyridine N,P,P{prime}-trioxides (NOPOPO) as potential reagents for the separation of Am, Cm, and fission product lanthanides from other transuranics and fission products and for acting as a separations 'platform' for the mutual separation of Am/Cm from the lanthanides. The secondary but critical objective of the project focused on the characterization of aqueous acid and radiation stability of NOPOPO ligands. Further, the project served as a interdisciplinary training vehicle for new, young investigators in actinide separations chemistry.

Robert T. Paine

2009-12-04

105

Gas Separation Using Organic-Vapor-Resistent Membranes In Conjunctin With Organic-Vapor-Selective Membranes  

DOEpatents

A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The second-gas-selective membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons. The membrane steps can be combined in either order.

Baker, Richard W. (Palo Alto, CA); Pinnau, Ingo (Palo Alto, CA); He, Zhenjie (Fremont, CA); Da Costa, Andre R. (Menlo Park, CA); Daniels, Ramin (San Jose, CA); Amo, Karl D. (Mountain View, CA); Wijmans, Johannes G. (Menlo Park, CA)

2003-06-03

106

Improved Fat Water Separation with Water Selective Inversion Pulse for Inversion Recovery Imaging in Cardiac MRI  

PubMed Central

Purpose To develop an improved chemical shift-based water-fat separation sequence using a water-selective inversion pulse for inversion-recovery 3D contrast-enhanced cardiac MR. Materials and Methods In inversion-recovery sequences, the fat signal is substantially reduced due to the application of a non-selective inversion pulse. Therefore, for simultaneous visualization of water, fat, and myocardial enhancement in inversion-recovery based sequences such as late Gadolinium enhancement imaging, two separate scans are used. To overcome this, the non-selective inversion pulse is replaced with a water-selective inversion pulse. Imaging was performed in phantoms, 9 healthy subjects and 9 patients with suspected arrhythmogenic right ventricular cardiomyopathy plus 1 patient for tumor/mass imaging. In patients, images with conventional turbo-spin echo (TSE) with and without fat saturation were acquired prior to contrast injection for fat assessment. Subjective image scores (1=poor, 4=excellent) were used for image assessment. Results Phantom experiments showed a fat SNR increase between 1.7 to 5.9 times for inversion times of 150 and 300ms, respectively. The water-selective inversion pulse retains the fat signal in contrast-enhanced cardiac MR, allowing improved visualization of fat in the water-fat separated images of healthy subjects with a score of 3.7 ± 0.6. Patient images acquired with the proposed sequence were scored higher when compared with TSE sequence (3.5 ± 0.7 vs. 2.2 ± 0.5, p<0.05). Conclusion The water-selective inversion pulse retains the fat signal in inversion-recovery based contrast-enhanced cardiac MR, allowing simultaneous visualization of water and fat. PMID:22927327

Havla, Lukas; Basha, Tamer; Rayatzadeh, Hussein; Shaw, Jaime L.; Manning, Warren J.; Reeder, Scott B.; Kozerke, Sebastian; Nezafat, Reza

2012-01-01

107

Selective Separation and Determination of Heavy Metals (Cd, Pb, Cr) Speciation Forms from Hortic Antrosols  

NASA Astrophysics Data System (ADS)

The speciation, inter-phases distribution and biodisponibility of heavy metals in soils represent one of main problem of environmental geochemistry and agro-chemistry. This problem is very important in case of hortic antrosols (soils from glasshouses) for the elimination of agricultural products (fruits, vegetables) contamination with heavy metals. In soils from glass houses, the speciation and inter-phases distribution processes of heavy metals have a particular dynamic, different in comparison with those from non-protected soils. The predominant distribution forms of heavy metals in such soils types are: complexes with low mass organic molecules, organic-mineral complexes, complexes with inorganic ligands (hydroxide-complexes, carbonate-complexes, sulphate-complexes, etc.) and basic salts. All of these have high stabilities in conditions of soils from glass houses, and in consequence, the separation and determination of speciation forms (which is directly connected with biodisponibility of heavy metals) by usual methods id very difficult and has a high uncertain degree. In this study is presented an original method for the selective separation and differentiation of speciation forms of heavy metals from glass houses soils, which is based by the combination of solid-liquid sequential extraction (SPE) with the extraction in aqueous polymer-inorganic salt two-phase systems (ABS). The soil samples used for this study have been sampled from three different locations (glass houses from Iasi, Barlad and Bacau - Romania) where the vegetables cultivation have bee performed by three different technologies. In this way was estimated the applicability and the analytical limits of method proposed by as, in function of the chemical-mineralogical and physical-chemical characteristics of soils. As heavy metals have been studied cadmium, lead and chromium, all being known for their high toxicity. The procedure used for the selective separation and differentiation of speciation forms of heavy metals from glass houses soils has two main steps: (i) non-destructive separation of chemical-mineralogical associations and aggregates from soils samples - for this the separation method with heavy liquids (bromophorme) and isodynamic magnetic method have been used; (ii) sequential extraction of heavy metals from soil fractions separated in the first step, by using combined SPE-ABS procedure. For the preparation of combined extraction systems was used polyethylene glycol (with different molecular mass: 2000, 4000 and 8000). As phase-forming inorganic salts and as selective extracting agents we have used different usual inorganic reagents. The type and concentration of phase-forming salts have been selected in function of, both nature of extracted heavy metals and chemical-mineralogical characteristics of soil samples. The experimental parameters investigated in this study are: molecular mass of polyethylene glycol and the concentration of polymeric solutions, nature and concentration of phase-forming salts, nature and concentration of extracting agents, pH in extraction system phase, type of extracted heavy metals, type of speciation forms of heavy metals and their concentrations. All these factors can influence significantly the efficiency and the selectivity of separation process. The experimental results have indicate that the combined SPE-ABS extraction systems have better separation efficiency, in comparison with traditional SPE systems and ca realized a accurate discrimination between speciation forms of heavy metals from soils. Under these conditions, the estimation of inter-phases distribution and biodisponibility of heavy metals has a high precision. On the other hand, when the combined SPE-ABS systems are used, the concomitant extraction of the elements from the same geochemical association with studied heavy metals (inevitable phenomena in case of separation by SPE procedures) is significant diminished. This increases the separation selectivity and facilitated the more accurate determination of speciation forms concentration. By adequat

Bulgariu, D.; Bulgariu, L.

2009-04-01

108

Selective comprehensive multidimensional separation for resolution enhancement in high performance liquid chromatography. Part II: applications.  

PubMed

In this second paper of a two-part series, we demonstrate the utility of an approach to enhancing the resolution of select portions of conventional 1D-LC separations, which we refer to as selective comprehensive two-dimensional HPLC (sLC × LC), in three quite different example applications. In the first paper of the series we described the principles of this approach, which breaks the long-standing link in online multi-dimensional chromatography between the timescales of sampling the first dimension (¹D) separation and the separation of fractions of ¹D effluent in the second dimension. In the first example, the power of the sLC × LC approach to significantly reduce the analysis time and method development effort is demonstrated by selectively enhancing the resolution of critical pairs of peaks that are unresolved by a one-dimensional separation (1D-LC) alone. Transfer and subsequent ²D separations of multiple fractions of a particular ¹D peak produces a two-dimensional chromatogram that reveals the coordinates of the peaks in the 2D separation space. The added time dimension of sLC × LC chromatograms also facilitates the application of sophisticated chemometric curve resolution algorithms to further resolve peaks that are otherwise chromatographically unresolved. This is demonstrated in this work by the targeted analysis of phenytoin in urban wastewater effluent using UV diode array detection. Quantitation by both standard addition and external calibration methods yielded results that were not statistically different from 2D-LC/MS/MS analysis of the same samples. Next, we demonstrate the utility of sLC × LC for reducing ion suppression due to matrix effects in electrospray ionization mass spectrometry through the analysis of cocaine in urban wastewater effluent. Finally, we explore the flexibility of the approach in its application to two select regions of a single ¹D separation of triclosan and cocaine. The diversity of these applications demonstrates the power and versatility of the sLC × LC approach, which will benefit tremendously from further optimization and advances in valve technology that specifically address the needs of this new technique. PMID:21816400

Groskreutz, Stephen R; Swenson, Michael M; Secor, Laura B; Stoll, Dwight R

2012-03-01

109

Stochastic band selection method based on a spectral angle class separability criterion  

NASA Astrophysics Data System (ADS)

Band selection methods often suppose normal distribution or, at least, a significant number of samples per class to compute statistical parameters. In this paper, we propose a band selection technique that needs very few training samples per class to be effective. To take into account the spectral variability inside the classes and to be independent on statistic parameters, we propose to use a criterion which measures the separability between two classes. This criterion is based on the extension of Spectral Angle Mapper (SAM) to a SAM within- and between-classes. The proposed selection method consists in eliminating spectral bands from the original set, thanks to the previous criterion that check the increase of separability measure between classes on the remaining bands subset. We use a stochastic algorithm to choose, at each step, which band to eliminate. We proceed by successive elimination until we reach the number of desired bands or the maximum of the criterion. This top-down method allows taking simultaneously into account all the interesting bands during the whole process, instead of selecting them one by one. The method provides, at the end, the selected spectral bands for a pair of classes. We expand this two-class selection technique to the multiclass band selection. We improve the method by adding a pre-selection of interesting bands considering a measure of a spectral signal on noise ratio. Some examples are given to show the effectiveness of the method: as one main application is classification, we compare the results of classification achieved after the data reduction made by different methods. We check the efficiency according to the number of training samples.

Déliot, Ph.; Kervella, M.

2010-10-01

110

Chromatographic separation as selection process for prebiotic evolution and the origin of the genetic code.  

PubMed

A model for the evolution of a translation apparatus has been suggested where oligonucleotides in a hairpin conformation act as primordial adapters. Specifically activated amino acids are assumed to be attached to these hairpin molecules. For the specific activation, a chromatographic separation of, e.g. ala and CMP from gly and GMP can be accomplished on silica (e.g. of volcanic origin) with aqueous salt solutions. Other adsorbents like clays (kaolin, bentonite, montmorillonite), different silicates (florisil, magnesium trisilicate, calcium silicate, talc), hydroxyapatite, barium sulfate, calcium carbonate, calcium fluoride and titanoxide have been examined as model systems for the separation of nucleotides, nucleosides and amino acids on mineral surfaces. The possible role of chromatographic separation of amino acids for the formation of proteinoids, composed of selected amino acids, is also considered. PMID:3995160

Lehmann, U

1985-01-01

111

The Use of Polyacrylamide as a Selective Depressant in the Separation of Chalcopyrite and Galena  

NASA Astrophysics Data System (ADS)

High molecular weight polyacrylamide (PAM) was tested as a potential selective depressant in the differential flotation separation of galena and chalcopyrite using potassium ethyl xanthate (KEX) as a collector. In single mineral flotation, PAM depressed chalcopyrite while galena was floatable. Mechanism study indicated that PAM could adsorb on galena through hydrogen bonding, and on chalcopyrite through hydrogen bonding as well as ammonium-copper complexation. KEX could only break up the galena-PAM bonding. It is the combined use of PAM and KEX that caused the selectivity. In mineral mixture flotation, galena and chalcopyrite could be separated by PAM and KEX only after EDTA treatment of the mineral mixtures. Time of flight secondary ion mass spectrometric (ToF-SIMS) measurements indicated that when galena and chalcopyrite were present together in the suspension, PAM adsorbed on both galena and chalcopyrite. However, after prior treatment of the mineral mixture by EDTA, PAM mainly adsorbed on chalcopyrite.

Wang, Lei

112

A block coordinate gradient descent method for regularized convex separable optimization and covariance selection  

Microsoft Academic Search

We consider a class of unconstrained nonsmooth convex optimization problems, in which the objective function is the sum of\\u000a a convex smooth function on an open subset of matrices and a separable convex function on a set of matrices. This problem\\u000a includes the covariance selection problem that can be expressed as an ?\\u000a 1-penalized maximum likelihood estimation problem. In this

Sangwoon Yun; Paul Tseng; Kim-Chuan Toh

113

Highly Selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications  

SciTech Connect

Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective H2 separation from other light gases (CO2, CH4, CO). However, current zeolite membranes have either too big zeolite pores or a large number of defects and have not been successful for H2 separation from light gases. The objective of this study is to develop zeolite membranes that are more suitable for H2 separation. In an effort to tune the size of zeolite pores and/or to decrease the number of defects, medium-pore zeolite B-ZSM-5 (MFI) membranes were synthesized and silylated. Silylation on B-ZSM-5 crystals reduced MFI-zeolite pore volume, but had little effect on CO2 and CH4 adsorption. Silylation on B-ZSM-5 membranes increased H2 selectivity both in single component and in mixtures with CO2, CH4, or N2. Single gas and binary mixtures of H2/CO2 and H2/CH4 were permeated through silylated B-ZSM-5 membranes at feed pressures up to 1.7 MPa and temperatures up to 773 K. For one B-ZSM-5 membrane after silylation, the H2/CO2 separation selectivity at 473 K increased from 1.4 to 37, whereas the H2/CH4 separation selectivity increased from 1.6 to 33. Hydrogen permeance through a silylated BZSM-5 membrane was activated with activation energy of {approx}10 kJ/mol, but the CO2 and CH4 permeances decreased slightly with temperature in both single gas and in mixtures. Therefore, the H2 permeance and H2/CO2 and H2/CH4 separation selectivities increased with temperature. At 673 K, the H2 permeance was 1.0x10-7 mol{center_dot}m-2{center_dot}s-1{center_dot}Pa-1, and the H2/CO2 separation selectivity was 47. Above 673 K, the silylated membrane catalyzed reverse water gas shift reaction and still separated H2 with high selectivity; and it was thermally stable. However, silylation decreased H2 permeance more than one order of magnitude. Increasing the membrane feed pressure increased the H2 flux and the H2 mole fraction in the permeate stream for both H2/CO2 and H2/CH4 mixtures. The H2 separation performance of the silylated B-ZSM-5 membranes depended on the initial membrane quality and acidity, as well as the silane precursors. Another approach used in this study is optimizing the synthesis of small-pore SAPO-34 (CHA) membranes and/or modifying SAPO-34 membranes by silylation or ion exchange. For SAPO-34 membranes, strong CO2 adsorption inhibited H2 adsorption and decreased H2 permeances, especially at low temperatures. At 253 K, CO2/H2 separation selectivities of a SAPO-34 membrane were greater than 100 with CO2 permeances of about 3 x 10-8 mol{center_dot}m-2{center_dot}s-1{center_dot}Pa-1. The high reverse-selectivity of the SAPO-34 membranes can minimize H2 recompression because H2 remained in the retentate stream at a higher pressure. The CO2/H2 separation selectivity exhibited a maximum with CO2 feed concentration possibly caused by a maximum in the CO2/H2 sorption selectivity with increased CO2 partial pressure. The SAPO-34 membrane separated H2 from CH4 because CH4 is close to the SAPO-34 pore size so its diffusivity (ABSTRACT TRUNCATED)

Mei Hong; Richard Noble; John Falconer

2007-09-24

114

Novel syntergistic agent for selective separation of yttrium from other rare earth metals  

SciTech Connect

An oil-soluble synergistic agent has been developed for the selective separation of yttrium (Y) from the other rare earth metals. The synergistic agent is a polyaminocarboxylic acid alkylderivative and has interfacial activity like that of surfactants. Separation of yttrium from heavy rare earth metals (erbium (Er) and holmium (Ho)) in the presence of the synergistic agent was carried out with a 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester as a carrier using a hollow-fiber membrane extractor. The new agent shows a synergistic effect on the permeation rate of rare earth metals at the oil-water interface. By the addition of a small amount of the agent, the selectivity for yttrium from the two rare earth metals was enhanced remarkably, because of the permeation rate of Y was selectively decreased compared with those of Er and Ho. The synergistic effect is discussed from the viewpoint of the stability constant for rare earth metals and the interfacial activity of the synergistic agent. The difference in interaction between the synergistic agent and rare earth ions at the oil-water interface results in an increase in the separation efficiency.

Miyata, Terufumi; Goto, Masahiro; Nakashio, Fumiyuki [Kyushu Univ., Fukuoka (Japan)

1995-06-01

115

Method for converting uranium oxides to uranium metal  

DOEpatents

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

Duerksen, Walter K. (Norris, TN)

1988-01-01

116

Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method  

SciTech Connect

More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste polymers cause serious environmental problems. Burning polymers for recycling is not practiced since poisonous gases are released during the burning process. Particularly, polyvinyl chloride (PVC) materials among waste polymers generate hazardous HCl gas, dioxins containing Cl, etc., which lead to air pollution and shorten the life of the incinerator. In addition, they make other polymers difficult to recycle. Both polyethylene terephthalate (PET) and PVC have densities of 1.30-1.35 g/cm{sup 3} and cannot be separated using conventional gravity separation techniques. For this reason, polymer recycling needs new techniques. Among these techniques, froth flotation, which is also used in mineral processing, can be useful because of its low cost and simplicity. The main objective of this research is to recycle PET and PVC selectively from post-consumer polymer wastes and virgin polymers by using froth flotation. According to the results, all PVC particles were floated with 98.8% efficiency in virgin polymer separation while PET particles were obtained with 99.7% purity and 57.0% efficiency in post-consumer polymer separation.

Burat, Firat; Gueney, Ali [Istanbul Technical University, Faculty of Mines, Mineral Processing Engineering Department, 34469 Maslak, Istanbul (Turkey); Olgac Kangal, M. [Istanbul Technical University, Faculty of Mines, Mineral Processing Engineering Department, 34469 Maslak, Istanbul (Turkey)], E-mail: kangal@itu.edu.tr

2009-06-15

117

Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method.  

PubMed

More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste polymers cause serious environmental problems. Burning polymers for recycling is not practiced since poisonous gases are released during the burning process. Particularly, polyvinyl chloride (PVC) materials among waste polymers generate hazardous HCl gas, dioxins containing Cl, etc., which lead to air pollution and shorten the life of the incinerator. In addition, they make other polymers difficult to recycle. Both polyethylene terephthalate (PET) and PVC have densities of 1.30-1.35g /cm(3) and cannot be separated using conventional gravity separation techniques. For this reason, polymer recycling needs new techniques. Among these techniques, froth flotation, which is also used in mineral processing, can be useful because of its low cost and simplicity. The main objective of this research is to recycle PET and PVC selectively from post-consumer polymer wastes and virgin polymers by using froth flotation. According to the results, all PVC particles were floated with 98.8% efficiency in virgin polymer separation while PET particles were obtained with 99.7% purity and 57.0% efficiency in post-consumer polymer separation. PMID:19155169

Burat, Firat; Güney, Ali; Olgaç Kangal, M

2009-06-01

118

YIELD AND RANGE STUDIES OF SELECTED FISSION PRODUCTS FROM URANIUM BOMBARDED WITH BEV PROTONS  

Microsoft Academic Search

In onder to obtain information about the mechanism of the breakup of the ; uranium nucleus at high bombarding energies, uranium foils were bombarded with ; 0.72 and 6.2 Bev protons. The formation cross scctions and the ranges of Cu\\/sup ; 67\\/, Mo⁹⁹, and Ag¹¹¹ were determined by radiochemical means. The ; yields of several isotopes of molybdenum were investigated

Baltzinger

1958-01-01

119

Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Paducah Gaseous Diffusion Plant site  

SciTech Connect

Uranium enrichment in the United States has utilized a diffusion process to preferentially enrich the U-235 isotope in the uranium product. The U-AVLIS process is based on electrostatic extraction of photoionized U-235 atoms from an atomic vapor stream created by electron-beam vaporization of uranium metal alloy. The U-235 atoms are ionized when precisely tuned laser light -- of appropriate power, spectral, and temporal characteristics -- illuminates the uranium vapor and selectively photoionizes the U-235 isotope. A programmatic document for use in screening DOE site to locate a U-AVLIS production plant was developed and implemented in two parts. The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. These sites were subjected to a more rigorous and detailed comparative analysis for the purpose of developing a short list of reasonable alternative sites for later environmental examination. This environmental site description (ESD) provides a detailed description of the PGDP site and vicinity suitable for use in an environmental impact statement (EIS). The report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during a site visit. 65 refs., 15 tabs.

Marmer, G.J.; Dunn, C.P.; Moeller, K.L.; Pfingston, J.M.; Policastro, A.J.; Yuen, C.R.; Cleland, J.H. (ed.)

1991-09-01

120

Uranium hexafluoride handling. Proceedings  

SciTech Connect

The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF{sub 6} from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride. Selected papers were processed separately for inclusion in the Energy Science and Technology Database.

Not Available

1991-12-31

121

Synthesis of magnetic ion-imprinted composites and selective separation and preconcentration of U(VI).  

PubMed

The U(VI) magnetic ion-imprinted composite (MIIC) with a uniform core-shell structure for the selective separation and preconcentration of U(VI) was prepared by copolymerization of a ternary complex of uranyl ions with 4-vinylpyridine (4-VP) and acrylamide in the presence of 2,2'-azobisisobutyronitrile. The sorption of U(VI) on the MIIC from aqueous solution was evaluated. The maximum sorption capacity of MIIC for U(VI) was 354.85 mg g(-1), which was much higher than that of the magnetic nonimprinted composite. The MIIC could be recovered by desorbing the U(VI)-loaded MIIC with 0.5 mol L(-1) HNO3, and the surface morphology of MIIC after five consecutive sorption/desorption cycles was significantly damaged. The competitive sorption experiments showed that the MIIC had a desirable selectivity for U(VI) over a range of competing metal ions. The MIIC may be a promising sorbent material for the selective separation and preconcentration of U(VI). PMID:24667936

Liu, Mancheng; Chen, Changlun; Wen, Tao; Wang, Xiangke

2014-05-21

122

Highly selective separation of aminoglycoside antibiotics on a zwitterionic Click TE-Cys column.  

PubMed

Hydrophilic interaction liquid chromatography has emerged as a valuable alternative approach to ion-pair chromatography for the separation of aminoglycoside antibiotics in recent years. However, the resolution of structurally related aminoglycosides is a great challenge owing to the limited selectivity. In this work, a cysteine-based zwitterionic stationary phase (named Click TE-Cys) was utilized and compared with five commonly used hydrophilic interaction liquid chromatography columns. Click TE-Cys displayed much better selectivity for structurally similar aminoglycosides. The retention behaviors of aminoglycosides were investigated in detail, revealing that low pH (2.7 or 3.0) and high buffer concentration (?50 mM) were preferable for achieving good peak shape and selectivity. Effective resolution of ten aminoglycosides including spectinomycin, dihydrostreptomycin, streptomycin, gentamicin C1, gentamicin C2/C2a, gentamicin C1a, kanamycin, paromonycin, tobramycin, and neomycin was realized at optimized conditions. Additionally, spectinomycin and its related impurities were successfully resolved. The results indicated the great potential of the Click TE-Cys column in the separation of aminoglycoside mixtures and related impurities. PMID:24798626

Wei, Jie; Shen, Aijin; Wan, Huihui; Yan, Jingyu; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2014-07-01

123

Imprint-coating synthesis of selective functionalized ordered mesoporous sorbents for separation and sensors  

DOEpatents

The present invention relates generally to mesoporous sorbent materials having high capacity, high selectivity, fast kinetics, and molecular recognition capability. The invention also relates to a process for preparing these mesoporous substrates through molecular imprinting techniques which differ from convention techniques in that a template molecule is bound to one end of bifunctional ligands to form a complex prior to binding of the bifunctional ligands to the substrate. The present invention also relates to methods of using the mesoporous sorbent materials, for example, in the separation of toxic metals from process effluents, paints, and other samples; detection of target molecules, such as amino acids, drugs, herbicides, fertilizers, and TNT, in samples; separation and/or detection of substances using chromatography; imaging agents; sensors; coatings; and composites.

Dai, Sheng (Knoxville, TN); Burleigh, Mark C. (Lenoir City, TN); Shin, Yongsoon (Richland, WA)

2001-01-01

124

Selective removal of sickle cells with the IBM 2997 continuous flow blood cell separator.  

PubMed

Partial red cell exchange transfusion is used to manage several complications of sickle cell anemia. Reports have stressed the safety, ease, and speed of red cell exchange procedures performed with blood cell separators, but little information exists concerning operating conditions for the most efficient removal of hemoglobin S (HbS) containing cells. We performed 13 red blood cell exchange transfusions with the IBM 2997 continuous flow blood cell separator on two previously transfused adult homozygous (SS) sickle cell patients. We used both a single stage and a dual stage disposable pathway and varied rotor speed, collection port, and collection interface independently. The patients' baseline percentage HbS ranged from 28 to 64% (mean = 46%); post exchange values ranged from 19.1 to 46% (mean = 32%). Thirty-three of 34 specimens collected from the white cell or platelet port showed a higher percentage of HbS in the collection line compared to simultaneous patient samples. Mean enrichment was 9.4% (range = -4.0 to 35.5%). There was an inverse relationship between the hemoglobin concentration and the percentage of HbS in the collected specimens (p = 0.001; N = 45). Differential separation of sickle cells should decrease the volume of blood required for partial red cell exchange of selected SS patients. PMID:6681483

Lenes, B; Klein, H G; Lakatos, E

1983-01-01

125

Selection and Separation of Viable Cells Based on a Cell-Lethal Assay  

PubMed Central

A method to select and separate viable cells based on the results of a cell-lethal assay was developed. Cells were plated on an array of culture sites with each site composed of closely spaced, releasable micropallets. Clonal colonies spanning multiple micropallets on individual culture sites were established within 72 h of plating. Adjacent sites were widely spaced with 100% of the colonies remaining sequestered on a single culture site during expansion. A laser-based method mechanically released a micropallet underlying a colony to segment the colony into two genetically identical colonies. One portion of the segmented colony was collected with 90% efficiency while viability of both fractions was 100%. The segmented colonies released from the array were fixed and subjected to immunofluorescence staining of intracellular phospho-ERK kinase to identify colonies that were highly resistant or sensitive to phorbol ester-induced activation of ERK. These resistant and sensitive cells were then matched to the corresponding viable colonies on the array. Sensitive and resistant colonies on the array were released and cultured. When these cultured cells were reanalyzed for phorbol ester-induced ERK activity, the cells retained the sensitive or resistant phenotype of the originally screened subcolony. Thus cells were separated and collected based using the result of a cell-lethal assay as selection criteria. These microarrays enabling clonal colony segmentation permitted sampling and manipulation of the colonies at very early times and at small cell numbers to reduce reagent, time and manpower requirements. PMID:21142138

Xu, Wei; Herman, Annadele; Phillips, Colleen; Pai, Jeng-Hao; Sims, Christopher E.; Allbritton, Nancy L.

2010-01-01

126

Metal separation from mixed types of batteries using selective precipitation and liquid-liquid extraction techniques.  

PubMed

The purpose of this paper is to study metal separation from a sample composed of a mixture of the main types of spent household batteries, using a hydrometallurgical route, comparing selective precipitation and liquid-liquid extraction separation techniques. The preparation of the solution consisted of: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution two different routes were studied: selective precipitation with sodium hydroxide and liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] as extracting agent. The best results were obtained from liquid-liquid extraction in which Zn had a 99% extraction rate at pH 2.5. More than 95% Fe was extracted at pH 7.0, the same pH at which more than 90% Ce was extracted. About 88% Mn, Cr and Co was extracted at this pH. At pH 3.0, more than 85% Ni was extracted, and at pH 3.5 more than 80% of Cd and La was extracted. PMID:20880689

Provazi, Kellie; Campos, Beatriz Amaral; Espinosa, Denise Crocce Romano; Tenório, Jorge Alberto Soares

2011-01-01

127

Calix[4]pyrroles: highly selective stationary phases for gas chromatographic separations.  

PubMed

Calix[4]pyrroles offer a great potential as stationary phases for gas chromatography (GC) due to their unique structures and physicochemical properties. Herein we present the first report of using two calix[4]pyrroles, namely meso-tetra-cyclohexylcalix[4]pyrrole (THCP) and meso-octamethylcalix[4]pyrrole (OMCP). These stationary phases were statically coated onto capillary columns and investigated in terms of column efficiency, polarity, separation performance, thermal stability and repeatability. The columns achieved column efficiencies of 2200-3000plates/m and exhibited nonpolar nature with an average polarity of 67 for THCP and 64 for OMCP, respectively. THCP stationary phase shows high selectivity for analytes of different polarity and exhibits nice peak shapes, especially for aldehydes, alcohols and anilines that are prone to severe peak tailing in GC analysis. Interestingly, THCP stationary phase possesses superior resolving ability for aniline and benzenediol positional isomers while OMCP shows preferential selectivity for nonpolar analytes such as hexane isomers. Moreover, calix[4]pyrrole columns also have good thermal stability up to 260°C and repeatability with a relative standard deviation (RSD%) of less than 0.10% for run-to-run and less than 5.2% for column-to-column. This work demonstrates the unique separation performance of calix[4]pyrroles and their promising future as a new class of GC stationary phases. PMID:25173993

Fan, Jing; Wang, Zhenzhong; Li, Qian; Qi, Meiling; Shao, Shijun; Fu, Ruonong

2014-10-01

128

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

SciTech Connect

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.

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

2003-02-25

129

Selective separation of rare earth metals by solvent extraction in the presence of new hyrophilic chelating polymers functionalized with ethylenediaminetetraacetic acid. II. Separation properties by solvent extraction  

SciTech Connect

The selective separation of rare earth metals by solvent extraction including chelating polymers in the aqueous phase was investigated. The chelating polymers were synthesized in this laboratory by introducing ethylenediaminetetraacetic acid (EDTA) onto water-soluble polyallylamine. The highest selectivity obtained for the Y/Er separation system was 14.7, which was much higher than that in extraction including EDTA (about 5.0). This means that the number of extraction stages required can be considerably reduced by the addition of chelating polymers. The effects of several experimental conditions such as pH, extractant concentrations, chelating polymer concentrations, and initial total rare earth metal concentrations, chelating polymer concentrations, and initial total rare earth metal concentrations on the separation factors and the distribution ratios for the Y/Er system were studied in detail. Furthermore, this extraction method was applied to other separation systems (Y/Dy, Y/Ho, Y/Tm). A remarkably high separation factor (12.6) was obtained for the Y/Tm system and the Y/Er system, although the separation factors were comparable to those in the presence of EDTA in the Y/Dy and Y/Ho systems.

Matsuyama, Hideto; Miyamoto, Yoshikazu; Teramoto, Masaaki [Kyoto Inst. of Technology, Kyoto (Japan)] [and others

1996-03-01

130

Just in Time-Selection: A Rapid Semiautomated SELEX of DNA Aptamers Using Magnetic Separation and BEAMing.  

PubMed

A semiautomated two-step method for in vitro selection of DNA aptamers using magnetic separation and solid-phase emulsion polymerase chain reaction has been developed. The application of a magnetic separator allows the simultaneous processing of up to 12 SELEXs (systematic evolution of ligands by exponential enrichment) with different targets or buffer conditions. Using a magnetic separator and covalent target immobilization on magnetic beads, the selection process was simplified and the substeps of aptamer/target incubation, washing, and elution of the aptamers were merged into one automated procedure called "FISHing". Without further processing the resulting FISHing eluates are suitable for BEAMing (beads, emulsion, amplification, and magnetics), which includes the amplification by emPCR (emulsion polymerase chain reaction) and strand separation by the implementation of covalently immobilized reverse primers on magnetic beads. The novel selection process has been proved and validated by selecting and characterization of aptamers to the wine fining agent lysozyme. PMID:25286022

Hünniger, Tim; Wessels, Hauke; Fischer, Christin; Paschke-Kratzin, Angelika; Fischer, Markus

2014-11-01

131

Molecular octopus: octa functionalized calix[4]resorcinarene-hydroxamic acid [C4RAHA] for selective extraction, separation and preconcentration of U(VI).  

PubMed

A solvent extraction separation of uranium, in the presence of thorium, cerium and lanthanides with a new calix[4]resorcinarene bearing eight hydroxamic acid groups (C4RAHA) is described. Quantitative extraction of uranium is possible in ethyl acetate solution of C4RAHA at pH 8.0. The lambda(max) and molar absorptivity (varepsilon) for uranium is 356nm and 8352Lmol(-1)cm(-1). The Binding ratio of uranium with C4RAHA as evaluated by Job's method is 4:1. The system obeys Beer's law over the range 0.075-6.0mugml(-1) of uranium with Sandell sensitivity 0.0284mugcm(-2). A preconcentration factor of 142 was achieved by directly aspirating the extract for GF-AAS measurements. The two-phase stability constant evaluated at 25 degrees C for uranium is 15.91. The complexation is characterized by favorable enthalpy and entropy changes. A liquid membrane transport study of uranium was carried out from source to the receiving phase under controlled conditions and a mechanism of transport is proposed. Uranium has been determined in standard and environmental samples. PMID:18969821

Jain, Vinod K; Pillai, Shibu G; Pandya, Rujul A; Agrawal, Yaduvendra K; Shrivastav, Pranav S

2005-01-30

132

Selective separation of lambdacyhalothrin by porous/magnetic molecularly imprinted polymers prepared by Pickering emulsion polymerization.  

PubMed

Porous/magnetic molecularly imprinted polymers (PM-MIPs) were prepared by Pickering emulsion polymerization. The reaction was carried out in an oil/water emulsion using magnetic halloysite nanotubes as the stabilizer instead of a toxic surfactant. In the oil phase, the imprinting process was conducted by radical polymerization of functional and cross-linked monomers, and porogen chloroform generated steam under the high reaction temperature, which resulted in some pores decorated with easily accessible molecular binding sites within the as-made PM-MIPs. The characterization demonstrated that the PM-MIPs were porous and magnetic inorganic-polymer composite microparticles with magnetic sensitivity (M(s) = 0.7448 emu/g), thermal stability (below 473 K) and magnetic stability (over the pH range of 2.0-8.0). The PM-MIPs were used as a sorbent for the selective binding of lambdacyhalothrin (LC) and rapidly separated under an external magnetic field. The Freundlich isotherm model gave a good fit to the experimental data. The adsorption kinetics of the PM-MIPs was well described by pseudo-second-order kinetics, indicating that the chemical process could be the rate-limiting step in the adsorption of LC. The selective recognition experiments exhibited the outstanding selective adsorption effect of the PM-MIPs for target LC. Moreover, the PM-MIPs regeneration without significant loss in adsorption capacity was demonstrated by at least four repeated cycles. PMID:23894024

Hang, Hui; Li, Chunxiang; Pan, Jianming; Li, Linzi; Dai, Jiangdong; Dai, Xiaohui; Yu, Ping; Feng, Yonghai

2013-10-01

133

Recovery of uranium alloy  

SciTech Connect

A method is described of recovery of uranium alloy from a mixture of uranium alloy with magnesium fluoride comprising: (a) pretreating uranium fluoride with magnesium at 400/sup 0/-1250/sup 0/C. to form a pretreated mixture of uranium and magnesium fluoride, (b) introducing the pretreated mixture into a molten-salt bath floating on a molten-uranium-alloy trap, (c) allowing the bath to transfer heat to the pretreated mixture to cause the magnesium fluoride to dissolve into the molten-salt bath and the uranium alloy to be molten, (d) allowing molten uranium alloy from the pretreated mixture in the bath to separate from the bath into the trap, (e) discharging separated molten-uranium alloy from the trap, and (f) discharging non-alloy components of the pretreated mixture along with excess molten salt from the bath.

Elliott, G.R.B.

1987-01-13

134

A Facile Approach Towards Multicomponent Supramolecular Structures: Selective Self-Assembly via Charge Separation  

PubMed Central

A novel approach towards the construction of multicomponent two-dimensional (2-D) and three-dimensional (3-D) metallosupramolecules is reported. Simply by mixing carboxylate and pyridyl ligands with cis-Pt(PEt3)2(OTf)2 in a proper ratio, coordination-driven self-assembly occurs, allowing for selective generation of discrete multicomponent structures via charge separation on the metal centers. Using this method, a variety of 2-D rectangles and 3-D prisms were prepared under mild conditions. Moreover, multicomponent self-assembly can also be achieved by supramolecule-to-supramolecule transformations. The products were characterized by 31P and 1H multinuclear NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and pulsed-field-gradient spin echo (PGSE) NMR techniques together with computational simulations. PMID:21053935

Zheng, Yao-Rong; Zhao, Zhigang; Wang, Ming; Ghosh, Koushik; Pollock, J. Bryant; Cook, Timothy R.; Stang, Peter J.

2010-01-01

135

Determination of uranium and rare-earth metals separation coefficients in LiCl–KCl melt by electrochemical transient techniques  

Microsoft Academic Search

The main step in the pyrometallurgical process of spent nuclear fuel recycling is a molten salt electrorefining. The knowledge of separation coefficients of actinides (U, Np, Pu and Am) and rare-earth metals (Y, La, Ce, Nd and Gd) is very important for this step. Usually the separation coefficients are evaluated from the formal standard potentials of metals in melts containing

S. A. Kuznetsov; H. Hayashi; K. Minato; M. Gaune-Escard

2005-01-01

136

Electrochemical transient techniques for determination of uranium and rare-earth metal separation coefficients in molten salts  

Microsoft Academic Search

The main step in the pyrometallurgical recycling process of spent nuclear fuel is a molten salt electrorefining. The knowledge of separation coefficients of actinides (U, Np, Pu and Am) and rare-earth metals (Y, La, Ce, Nd and Gd) is very important for this step. Usually the separation coefficients are evaluated from the formal standard potentials of metals in melts containing

S. A. Kuznetsov; H. Hayashi; K. Minato; M. Gaune-Escard

2006-01-01

137

Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) for highly selective separations  

SciTech Connect

Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) have been investigated for the realization as separation media with high selectivity. These structures are held together with strong bonds, making them architecturally, chemically, and thermally stable. Therefore, employing well designed building units, it is possible to discover promising materials for gas and vapor separation. This grant was focused on the study of MOFs and ZIFs with these specific objectives: (i) to develop a strategy for producing MOFs and ZIFs that combine high surface areas with active sites for their use in gas adsorption and separation of small organic compounds, (ii) to introduce active sites in the framework by a post-synthetic modification and metalation of MOFs and ZIFs, and (iii) to design and synthesize MOFs with extremely high surface areas and large pore volumes to accommodate large amounts of guest molecules. By the systematic study, this effort demonstrated how to introduce active functional groups in the frameworks, and this is also the origin of a new strategy, which is termed isoreticular functionalization and metalation. However, a large pore volume is still a prerequisite feature. One of the solutions to overcome this challenge is an isoreticular expansion of a MOF�������¢����������������s structure. With triangular organic linker and square building units, we demonstrated that MOF-399 has a unit cell volume 17 times larger than that of the first reported material isoreticular to it, and it has the highest porosity (94%) and lowest density (0.126 g cm-3) of any MOF reported to date. MOFs are not just low density materials; the guest-free form of MOF-210 demonstrates an ultrahigh porosity, whose BET surface area was estimated to be 6240 m2 g-1 by N2 adsorption measurements.

Omar M. Yaghi

2012-09-17

138

Air separation by single wall carbon nanotubes: Mass transport and kinetic selectivity  

NASA Astrophysics Data System (ADS)

Mass transport of pure nitrogen, pure oxygen, and their mixture (air) has been studied at 100 K in a single wall carbon nanotube of 12.53 Å diameter. Phenomenological coefficients, and self- and corrected diffusivities are calculated using molecular-dynamics simulations, and transport diffusivities are obtained by combining these results with thermodynamic factors obtained from previous grand canonical Monte Carlo simulations [G. Arora and S. I. Sandler, J. Chem. Phys. 123, 044705 (2005)]. For mixtures, cross-term diffusion coefficients are found to be of similar order of magnitude as main-term diffusion coefficients over the entire range of pressure studied. These results are then combined with a continuum description of mass transport to determine the ideal and kinetic separation factors for a nanotube membrane. High permeances are observed for both pure components and the mixture inside the nanotubes. The concentration profiles, diffusivity profiles, and membrane fluxes are calculated, and it is demonstrated that by carefully adjusting the upstream and downstream pressures, a good kinetic selectivity can be achieved for air separation using single wall carbon nanotubes.

Arora, Gaurav; Sandler, Stanley I.

2006-02-01

139

Separation of PS-PMMA block copolymers from PS precursors via selective adsorption on nanoprous silica  

NASA Astrophysics Data System (ADS)

We report a simple adsorption-based separation method using nanoporous silica in solution via controlling solvent quality to remove polystyrene (PS) homopolymers from polystyrene-poly(methyl methacrylate) (PS-PMMA) diblock copolymers. In particular, the solvent quality is controlled by employing binary mixed solvents of THF (good solvent) and isooctane (nonsolvent for both PS and PMMA). The aim of this work is to qualitatively study the competitive adsorption between PS and PS-PMMA and to provide a correlative understanding of polymer adsorption in nanopores with interaction chromatography techniques. In addition, the quantitative understanding of polymer adsorption is further employed to develop a simple polymer separation scheme for manipulating polymer adsorption via solvent quality. In particular, concentration changes of PS and PS-PMMA in the supernatant solution have been quantitatively measured for the adsorption studies using solvent gradient interaction chromatography techniques. We found that the PS-PMMA (43k-32k) selectively adsorb over PS (43k) precursors at the THF composition window between 42 % and 55% in THF/IO (v/v) mixed solvents. For THF/IO solvents with composition higher than 60 % THF, polymers did not adsorb to the nanoporous silica due to the good solvent quality.

Ryu, Chang Yeol

2005-03-01

140

Bioremediation of uranium contamination with enzymatic uranium reduction  

USGS Publications Warehouse

Enzymatic uranium reduction by Desulfovibrio desulfuricans readily removed uranium from solution in a batch system or when D. desulfuricans was separated from the bulk of the uranium-containing water by a semipermeable membrane. Uranium reduction continued at concentrations as high as 24 mM. Of a variety of potentially inhibiting anions and metals evaluated, only high concentrations of copper inhibited uranium reduction. Freeze-dried cells, stored aerobically, reduced uranium as fast as fresh cells. D. desulfuricans reduced uranium in pH 4 and pH 7.4 mine drainage waters and in uraniumcontaining groundwaters from a contaminated Department of Energy site. Enzymatic uranium reduction has several potential advantages over other bioprocessing techniques for uranium removal, the most important of which are as follows: the ability to precipitate uranium that is in the form of a uranyl carbonate complex; high capacity for uranium removal per cell; the formation of a compact, relatively pure, uranium precipitate.

Lovley, D. R.; Phillips, E. J. P.

1992-01-01

141

An evaluation of CO 2 and H 2 selective polymeric membranes for CO 2 separation in IGCC processes  

Microsoft Academic Search

The potential of CO2 and H2 selective polymeric membranes to separate CO2 from integrated coal gasification combined cycle power plants is examined. As a reference power plant a modified version of the Puertollano gasification plant has been defined. A detailed ASPEN model for the reference case has been developed. For the CO2 selective membranes single membrane module concepts as well

J. Franz; V. Scherer

2010-01-01

142

Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Portsmouth Gaseous Diffusion Plant site  

SciTech Connect

Uranium enrichment in the United States has utilized a diffusion process to preferentially enrich the U-235 isotope in the uranium product. In the 1970s, the US Department of Energy (DOE) began investigating more efficient and cost-effective enrichment technologies. In January 1990, the Secretary of Energy approved a plan for the demonstration and deployment of the Uranium Atomic Vapor Laser isotope Separation (U-AVLIS) technology with the near-term goal to provide the necessary information to make a deployment decision by November 1992. Initial facility operation is anticipated for 1999. A programmatic document for use in screening DOE sites to locate a U-AVLIS production plant was developed and implemented in two parts. The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. The final evaluation, which included sensitivity studies, identified the Oak Ridge Gaseous Diffusion Plant (ORGDP) site, the Paducah Gaseous Diffusion Plant (PGDP) site, and the Portsmouth Gaseous Diffusion Plant (PORTS) site as having significant advantages over the other sites considered. This environmental site description (ESD) provides a detailed description of the PORTS site and vicinity suitable for use in an environmental impact statement (EIS). This report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during site visits. The organization of the ESD is as follows. Topics addressed in Sec. 2 include a general site description and the disciplines of geology, water resources, biotic resources, air resources, noise, cultural resources, land use. Socioeconomics, and waste management. Identification of any additional data that would be required for an EIS is presented in Sec. 3.

Marmer, G.J.; Dunn, C.P.; Filley, T.H.; Moeller, K.L.; Pfingston, J.M.; Policastro, A.J.; Cleland, J.H.

1991-09-01

143

In-line assay monitor for uranium hexafluoride  

DOEpatents

An in-line assay monitor for determining the content of uranium-235 in a uranium hexafluoride gas isotopic separation system is provided which removes the necessity of complete access to the operating parameters of the system for determining the uranium-235 content. The method and monitor for carrying out the method involve cooling of a radiation pervious chamber connected in fluid communication with the selected point in the system to withdraw a specimen and solidify the specimen in the chamber. The specimen is irradiated by means of an ionizing radiation source of energy different from that of the 185 keV gamma emissions from uranium-235. The uranium-235 content of the specimen is determined from comparison of the accumulated 185 keV energy counts and reference energy counts. The latter is used to measure the total uranium isotopic content of the specimen.

Wallace, S.A.

1980-03-21

144

Selectivity differences of water-soluble vitamins separated on hydrophilic interaction stationary phases.  

PubMed

In this study, the retention behavior and selectivity differences of water-soluble vitamins were evaluated with three types of polar stationary phases (i.e. an underivatized silica phase, an amide phase, and an amino phase) operated in the hydrophilic interaction chromatographic mode with ESI mass spectrometric detection. The effects of mobile phase composition, including buffer pH and concentration, on the retention and selectivity of the vitamins were investigated. In all stationary phases, the neutral or weakly charged vitamins exhibited very weak retention under each of the pH conditions, while the acidic and more basic vitamins showed diverse retention behaviors. With the underivatized silica phase, increasing the salt concentration of the mobile phase resulted in enhanced retention of the acidic vitamins, but decreased retention of the basic vitamins. These observations thus signify the involvement of secondary mechanisms, such as electrostatic interaction in the retention of these analytes. Under optimized conditions, a baseline separation of all vitamins was achieved with excellent peak efficiency. In addition, the effects of water content in the sample on retention and peak efficiency were examined, with sample stacking effects observed when the injected sample contained a high amount of water. PMID:23554360

Yang, Yuanzhong; Boysen, Reinhard I; Hearn, Milton T W

2013-06-01

145

Removal of uranium from uranium-contaminated soils -- Phase 1: Bench-scale testing. Uranium in Soils Integrated Demonstration  

SciTech Connect

To address the management of uranium-contaminated soils at Fernald and other DOE sites, the DOE Office of Technology Development formed the Uranium in Soils Integrated Demonstration (USID) program. The USID has five major tasks. These include the development and demonstration of technologies that are able to (1) characterize the uranium in soil, (2) decontaminate or remove uranium from the soil, (3) treat the soil and dispose of any waste, (4) establish performance assessments, and (5) meet necessary state and federal regulations. This report deals with soil decontamination or removal of uranium from contaminated soils. The report was compiled by the USID task group that addresses soil decontamination; includes data from projects under the management of four DOE facilities [Argonne National Laboratory (ANL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and the Savannah River Plant (SRP)]; and consists of four separate reports written by staff at these facilities. The fundamental goal of the soil decontamination task group has been the selective extraction/leaching or removal of uranium from soil faster, cheaper, and safer than current conventional technologies. The objective is to selectively remove uranium from soil without seriously degrading the soil`s physicochemical characteristics or generating waste forms that are difficult to manage and/or dispose of. Emphasis in research was placed more strongly on chemical extraction techniques than physical extraction techniques.

Francis, C. W.

1993-09-01

146

Modeling of the Microchemistry for Diffusion of Selected Impurities in Uranium  

SciTech Connect

Unalloyed metallic uranium used in some work done at Y-12 contains small quantities of impurities, the three most significant of which are carbon, iron, and silicon. During metallurgical processing, as the metal cools from a molten condition towards room temperature, the metallic matrix solution becomes supersaturated in each of the impurities whose concentration exceeds the solubility limit. Many impurity atoms form compounds with uranium that precipitate out of the solution, thus creating and growing inclusions. The objective of the present work is to study the distribution of impurity atoms about some of the inclusions, with a view toward examining the effect of the interaction between inclusions on the impurity atom distribution. The method used is time-dependent mass diffusion from the supersaturated solution to the surfaces of the inclusions. Micrographs of metal samples suggest that the inclusions form in successive stages. After each inclusion forms, it begins to draw impurity atoms from its immediate vicinity, thus altering the amounts and distributions of impurity atoms available for formation and growth of later inclusions. In the present work, a one-dimensional spherical approximation was used to simulate inclusions and their regions of influence. A first set of calculations was run to simulate the distribution of impurity atoms about the largest inclusions. Then, a second set of calculations was run to see how the loss of impurity atoms to the largest inclusions might affect the distribution of impurity atoms around the next stage of inclusions. Plots are shown for the estimated distributions of impurity atoms in the region of influence about the inclusions for the three impurities studied. The authors believe that these distributions are qualitatively correct. However, there is enough uncertainty about precisely when inclusions nucleate and begin to grow that one should not put too much reliance on the quantitative results. This work does provide a framework and an advance toward a comprehensive model of uranium metal microchemical distributions.

Kirkpatrick, J. R.; Bullock, J.S. IV

2001-09-01

147

Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent.  

PubMed

One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III. PMID:23932372

Kifle, Dejene; Wibetoe, Grethe

2013-09-13

148

Selection of water-dispersible carbon black for fabrication of uranium oxicarbide microspheres  

NASA Astrophysics Data System (ADS)

Fabrication of uranium oxicarbide microspheres, a component of TRISO fuel particles for high temperature nuclear power systems, is based on the internal gelation of uranium salts in the presence of carbon black. In order to obtain a high quality product, carbon black should remain dispersed during all phases of the gelation process. In this study, the surface and structural properties of several commercial carbon black materials, and the use of dispersing agents was examined with the goal of finding optimal conditions for stabilizing submicron-sized carbon black dispersions. Traditional methods for stabilizing dispersions, based on the use of dispersing agents, failed to stabilize carbon dispersions against large pH variations, typical for the internal gelation process. An alternate dispersing method was proposed, based on using surface-modified carbons functionalized with strongly ionized surface groups (sodium sulfonate). With a proper choice of surface modifiers, these advanced carbons disperse easily to particles in the range of 0.15-0.20 ?m and the dispersions remain stable during the conditions of internal gelation.

Contescu, Cristian I.; Baker, Frederick S.; Hunt, Rodney D.; Collins, Jack L.; Burchell, Timothy D.

2008-03-01

149

Southern complex: geology, geochemistry, mineralogy, and mineral chemistry of selected uranium- and thorium-rich granites  

SciTech Connect

Four major rock groups are defined in the Southern Complex: the Bell Creek Granite (BCG), the Clotted Granitoids (CGR), the Albite Granite (AGR), and the Migmatite Complex. Metatexites of the Migmatite Complex are the oldest rocks and include paleosome of a metasedimentary and metavolcanic protolith represented by Banded Iron Formation, Banded Amphibolite, and Banded Gneisses, and interlayered or crosscutting leucogranites. The CGR span the range from metatexite to diatexite and represent in-situ partial melting of metapelitic layers in the protolith during intrusion of the BCG. The BCG cuts the migmatites, is locally cut by the CGR, and was derived by partial melting of a dominantly metasedimentary protolith at some depth below the presently exposed migmatites during a regional tectonothermal event. The Albite Granite is a 2km diameter, muscovite-fluorite-columbite-bearing intrusive stock that cuts all other major units. The thorium history of the BCG is a function of the history of monazite. The thorium history of the CGR is also dominated by monazite but the thorium content of this unit cannot be entirely accounted for by original restite monazite. The uranium history of the BCG and CGR was dominated by magmatic differentiation and post magmatic, metamorphic and supergene redistributions and is largely independent of the thorium history. The thorium and uranium history of the AGR was dominated by magmatic/deuteric processes unlike the BCG and CGR.

Hoffman, M.A.

1987-01-01

150

Selection of Water-Dispersible Carbon Black for Fabrication of Uranium Oxicarbide Microspheres  

SciTech Connect

Fabrication of uranium oxicarbide (UCO) microspheres, a component of TRISO fuel particles for high temperature nuclear power systems, is based on the internal gelation process of uranium salts in presence of carbon black. In order to obtain a high quality product, carbon black should remain dispersed during all phases of the gelation process. In this study, the surface and structural properties of several commercial carbon black materials, and their use in combination with ionic and non-ionic dispersing agents was examined with the goal of finding optimal conditions for stabilizing submicron-sized carbon black dispersions. Traditional methods for stabilizing dispersions, based on the use of dispersing agents, failed to stabilize carbon dispersions against large pH variations, typical for the internal gelation process. An alternate dispersing method was proposed, based on using surface-modified carbons functionalized with strongly ionizing surface groups (sodium sulfonate). With a proper choice of surface modifiers, these advanced carbons disperse easily to particles in the range of 0.15 V0.20 m and the dispersions remain stable during the conditions of internal gelation.

Contescu, Cristian I [ORNL; Baker, Frederick S [ORNL; Hunt, Rodney Dale [ORNL; Collins, Jack Lee [ORNL; Burchell, Timothy D [ORNL

2008-01-01

151

Summary report on reprocessing evaluation of selected inactive uranium mill tailings sites  

SciTech Connect

Sandia National Laboratories has been assisting the Department of Energy in the Uranium Mill Tailings Remedial Actions Program (UMTRAP) the purpose of which is to implement the provisions of Title I of Public Law 95-604, Uranium Mill Tailings Radiation Control Act of 1978.'' As part of this program, there was a need to evaluate the mineral concentration of the residual radioactive materials at some of the designated processing sites to determine whether mineral recovery would be practicable. Accordingly, Sandia contracted Mountain States Research and Development (MSRD), a division of Mountain States Mineral Enterprises, to drill, sample, and test tailings at 12 sites to evaluate the cost of and the revenue that could be derived from mineral recovery. UMTRAP related environmental and engineering sampling and support activities were performed in conjunction with the MSRD operations. This summary report presents a brief description of the various activities in the program and of the data and information obtained and summarizes the results. 8 refs., 9 tabs.

Not Available

1983-09-01

152

Separation and determination of lanthanides, thorium and uranium using a dual gradient in reversed-phase liquid chromatography.  

PubMed

Separation and determination of lanthanides, Th and U is of great relevance in different fields of science and technology. Reversed-phase high-performance liquid chromatography (RP-HPLC) using alpha-hydroxy isobutyric acid (alpha-HIBA) as an eluent on reversed-phase column modified to cation exchanger has been reported to achieve the separation. However, under those conditions, Th and U are eluted amongst lanthanides, making their quantification difficult due to overlapping with some of the lanthanides peaks. In this work, different chromatographic parameters (concentrations of eluent and ion interaction reagent, pH, etc.) were studied systematically to arrive at optimum chromatographic conditions. Using the dual (concentration and pH) gradient conditions, lanthanides, Th and U could be separated in 11 min by RP-HPLC with sequential elution of Th and U after the elution of all the lanthanides. The separation methodology was tested using SY-3 rock sample for the separation and determination of lanthanides, Th and U. The method allows an accurate determination of these elements in a single run using a single column. Also, the method is fast and cost-effective compared to the reported methods. PMID:15527129

Raut, Narendra M; Jaison, P G; Aggarwal, Suresh K

2004-10-15

153

Provisional zircon and monazite uranium-lead geochronology for selected rocks from Vermont  

USGS Publications Warehouse

This report presents the results of zircon and monazite uranium-lead (U-Pb) geochronologic analyses of 24 rock samples. The samples in this study were collected from mapped exposures identified while conducting either new, detailed (1:24,000-scale) geologic quadrangle mapping or reconnaissance mapping, both of which were used for compilation of the bedrock geologic map of Vermont. All of the collected samples were judged to be igneous rocks (either intrusive or extrusive) on the basis of field relations and geochemistry. The one exception is the Okemo Quartzite on Ludlow Mountain. These geochronologic data were used to supplement regional correlations between igneous suites on the basis of similar geochemistry and geologic mapping.

Aleinikoff, John N.; Ratcliffe, Nicholas M.; Walsh, Gregory J.

2011-01-01

154

Selected uranium product characteristics for the EBR-II spent-fuel treatment program  

SciTech Connect

The key step in the treatment of spent fuel from the Experimental Breeder Reactor II (EBR-II) at Argonne National Laboratory-West is electrorefining. In this process, chopped, irradiated U-10 Zr fuel is loaded into perforated steel baskets and used as the anode in the electrorefiner. A solid steel mandrel is used as the cathode onto which uranium metal deposits. Active metal fission products accumulate in the electrolyte, consisting primarily of molten LiCl/KCl (eutectic composition) and UCl{sub 3} (nominally 6 wt%). Noble metals, such as zirconium and ruthenium, are retained either in the emptied steel hulls or in the electrorefiner (e.g., dissolved in a cadmium pool beneath the pool of electrolyte).

Mariani, R.D.; Li, S.X.; Vaden, D.; Westphal, B.R.; Maddison, D.W.; Sayer, M. [Argonne National Lab.-West, Idaho Falls, ID (United States)

1997-12-01

155

Pre-selection of flocculants by the LUMiFuge separation analyser 114.  

PubMed

This paper reports on lab-scale investigations in relation to pre-selection of flocculants for sludge dewatering with decanter centrifuges. Results obtained were compared with CST-measurements and discussed in relation to findings under field conditions. Experiments were carried out with sewage sludges of different origin and characteristics and a number of commercial flocculants. Kinetics of sedimentation and clarification were measured as well as the compression behaviour and shear sensitivity of sludge sediments. To measure flocculant performance stability against intensive shearing, total solids in the sludge cake obtained and dewaterability of the sludge cake during the first 20-50 s of centrifugation were compared. A screening test procedure was developed. Efficient flocculants should produce high residual total solids and good initial compressibility. Lab-scale investigations deliver more reliable results if the dynamic behaviour of the sludge under centrifugal acceleration is also investigated. The separation analyser LUMiFuge 114 can provide results about the compression behaviour of sludges in the range between 10 and 100 s. So far no other method or device is known which can deliver such results. PMID:12361046

Sobisch, T; Lerche, D

2002-01-01

156

Fluorous microgel star polymers: selective recognition and separation of polyfluorinated surfactants and compounds in water.  

PubMed

Immiscible with either hydrophobic or hydrophilic solvents, polyfluorinated compounds (PFCs) are generally "fluorous", some of which have widely been employed as surfactants and water/oil repellents. Given the prevailing concern about the environmental pollution and the biocontamination by PFCs, their efficient removal and recycle from industrial wastewater and products are critically required. This paper demonstrates that fluorous-core star polymers consisting of a polyfluorinated microgel core and hydrophilic PEG-functionalized arms efficiently and selectively capture PFCs in water into the cores by fluorous interaction. For example, with over 10?000 fluorine atoms in the core and approximately 100 hydrophilic arms, the fluorous stars remove perfluorooctanoic acid (PFOA) and related PFCs in water from 10 ppm to as low as a parts per billion (ppb) level, or an over 98% removal. Dually functionalized microgel-core star polymers with perfluorinated alkanes and additional amino (or ammonium) groups cooperatively recognize PFOA or its ammonium salt and, in addition, release the guests upon external stimuli. The "smart" performance shows that the fluorous-core star polymers are promising PFC separation, recovery, and recycle materials for water purification toward sustainable society. PMID:25300369

Koda, Yuta; Terashima, Takaya; Sawamoto, Mitsuo

2014-11-01

157

Uranium industry annual 1998  

SciTech Connect

The Uranium Industry Annual 1998 (UIA 1998) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. It contains data for the period 1989 through 2008 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data provides a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Data on uranium raw materials activities for 1989 through 1998, including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment, are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2008, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, and uranium inventories, are shown in Chapter 2. The methodology used in the 1998 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. The Form EIA-858 ``Uranium Industry Annual Survey`` is shown in Appendix D. For the readers convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix E along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 24 figs., 56 tabs.

NONE

1999-04-22

158

Valence-associated uranium isotope fractionation of uranium enriched phosphate in a shallow aquifer, Lee County, Florida  

SciTech Connect

The source of anomalously high concentrations of uranium, characterized by U-234/U-238 activity ratios significantly less than unity, in shallow groundwaters of Lee County, Florida, was investigated. Uranium in cores samples was separated into U(IV) and U(VI) oxidation state fractions, and uranium analyses were conducted by alpha spectrometry. Uranium mobility was also studied in selected leaching experiments. Results indicate that mobilization of unusually soluble uranium, present in uranium enriched phosphate of the Pliocene age Tamiami Formation at determined concentrations of up to 729 ppm, is the source for high uranium concentrations in groundwater. In leaching experiments, approximately one-third of the uranium present in the uranium enriched phosphate was mobilized into the aqueous phase. Results of previous investigations suggest that U-234, produced in rock by U-238 decay, is selectively oxidized to U(VI). The uranium enriched phosphate studied in this investigation is characterized by selective reduction of U-234, with a pattern of increasing isotopic fractionation with core depth. As a consequence, U-234/U-238 activity ratios greater than 1.0 in the U(IV) fraction, and less than 1.0 in the U(VI) fraction have developed in the rock phase. In leaching experiments, the U(VI) fraction from the rock was preferentially mobilized into the aqueous phase, suggesting that U-234/U-238 activity ratios of leaching groundwaters are strongly influenced by the isotopic characteristics of the U(VI) fraction of rock. It is suggested that preferential leaching of U(VI), present in selectivity reduced uranium enriched phosphate, is the source for low activity ratio groundwaters in Lee County.

Weinberg, J.M. (Missimer and Associates, Cape Coral, FL (United States)); Levine, B.R. (Ecology and Environment, Tallahassee, FL (United States)); Cowart, J.B. (Florida State Univ., Tallahassee, FL (United States). Geology Dept.)

1993-03-01

159

Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Oak Ridge Gaseous Diffusion Plant Site  

SciTech Connect

In January 1990, the Secretary of Energy approved a plan for the demonstration and deployment of the Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) technology, with the near-term goal to provide the necessary information to make a deployment decision by November 1992. The U-AVLIS process is based on electrostatic extraction of photoionized U-235 atoms from an atomic vapor stream created by electron-beam vaporization of uranium metal alloy. A programmatic document for use in screening DOE sites to locate the U-AVLIS production plant was developed and implemented in two parts (Wolsko et al. 1991). The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. These sites were then subjected to a more rigorous and detailed comparative analysis for the purpose of developing a short list of reasonable alternative sites for later environmental examination. This environmental site description (ESD) provides a detailed description of the ORGDP site and vicinity suitable for use in an environmental impact statement (EIS). The report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during a site visit. The organization of the ESD is as follows. Topics addressed in Sec. 2 include a general site description and the disciplines of geology, water resources, biotic resources, air resources, noise, cultural resources, land use, socioeconomics, and waste management. Identification of any additional data that would be required for an EIS is presented in Sec. 3. Following the site description and additional data requirements, Sec. 4 provides a short, qualitative assessment of potential environmental issues. 37 refs., 20 figs., 18 tabs.

Not Available

1991-09-01

160

Evidence for isolated evolution of deep-sea ciliate communities through geological separation and environmental selection  

PubMed Central

Background Deep hypersaline anoxic basins (DHABs) are isolated habitats at the bottom of the eastern Mediterranean Sea, which originate from the ancient dissolution of Messinian evaporites. The different basins have recruited their original biota from the same source, but their geological evolution eventually constituted sharp environmental barriers, restricting genetic exchange between the individual basins. Therefore, DHABs are unique model systems to assess the effect of geological events and environmental conditions on the evolution and diversification of protistan plankton. Here, we examine evidence for isolated evolution of unicellular eukaryote protistan plankton communities driven by geological separation and environmental selection. We specifically focused on ciliated protists as a major component of protistan DHAB plankton by pyrosequencing the hypervariable V4 fragment of the small subunit ribosomal RNA. Geospatial distributions and responses of marine ciliates to differential hydrochemistries suggest strong physical and chemical barriers to dispersal that influence the evolution of this plankton group. Results Ciliate communities in the brines of four investigated DHABs are distinctively different from ciliate communities in the interfaces (haloclines) immediately above the brines. While the interface ciliate communities from different sites are relatively similar to each other, the brine ciliate communities are significantly different between sites. We found no distance-decay relationship, and canonical correspondence analyses identified oxygen and sodium as most important hydrochemical parameters explaining the partitioning of diversity between interface and brine ciliate communities. However, none of the analyzed hydrochemical parameters explained the significant differences between brine ciliate communities in different basins. Conclusions Our data indicate a frequent genetic exchange in the deep-sea water above the brines. The “isolated island character” of the different brines, that resulted from geological events and contemporary environmental conditions, create selective pressures driving evolutionary processes, and with time, lead to speciation and shape protistan community composition. We conclude that community assembly in DHABs is a mixture of isolated evolution (as evidenced by small changes in V4 primary structure in some taxa) and species sorting (as indicated by the regional absence/presence of individual taxon groups on high levels in taxonomic hierarchy). PMID:23834625

2013-01-01

161

Size-selective separation of submicron particles in suspensions with ultrasonic atomization.  

PubMed

Aqueous suspensions containing silica or polystyrene latex were ultrasonically atomized for separating particles of a specific size. With the help of a fog involving fine liquid droplets with a narrow size distribution, submicron particles in a limited size-range were successfully separated from suspensions. Performance of the separation was characterized by analyzing the size and the concentration of collected particles with a high resolution method. Irradiation of 2.4MHz ultrasound to sample suspensions allowed the separation of particles of specific size from 90 to 320nm without regarding the type of material. Addition of a small amount of nonionic surfactant, PONPE20 to SiO2 suspensions enhanced the collection of finer particles, and achieved a remarkable increase in the number of collected particles. Degassing of the sample suspension resulted in eliminating the separation performance. Dissolved air in suspensions plays an important role in this separation. PMID:24798229

Nii, Susumu; Oka, Naoyoshi

2014-11-01

162

Selection of water treatment processes special study. [Uranium Mill Tailings Remedial Action (UMTRA) Project  

SciTech Connect

Characterization of the level and extent of groundwater contamination in the vicinity of Title I mill sites began during the surface remedial action stage (Phase 1) of the Uranium Mill Tailings Remedial Action (UMTRA) Project. Some of the contamination in the aquifer(s) at the abandoned sites is attributable to milling activities during the years the mills were in operation. The restoration of contaminated aquifers is to be undertaken in Phase II of the UMTRA Project. To begin implementation of Phase II, DOE requested that groundwater restoration methods and technologies be investigated by the Technical Assistance Contractor (TAC). and that the results of the TAC investigations be documented in special study reports. Many active and passive methods are available to clean up contaminated groundwater. Passive groundwater treatment includes natural flushing, geochemical barriers, and gradient manipulation by stream diversion or slurry walls. Active groundwater.cleanup techniques include gradient manipulation by well extraction or injection. in-situ biological or chemical reclamation, and extraction and treatment. Although some or all of the methods listed above may play a role in the groundwater cleanup phase of the UMTRA Project, the extraction and treatment (pump and treat) option is the only restoration alternative discussed in this report. Hence, all sections of this report relate either directly or indirectly to the technical discipline of process engineering.

Not Available

1991-11-01

163

Magnetically separable nanocomposites with photocatalytic activity under visible light for the selective transformation of biomass-derived platform molecules  

EPA Science Inventory

Novel magnetically separable TiO2-guanidine-(Ni,Co)Fe2O4 nanomaterials were prepared and characterised by a series of techniques including XRD, SEM, TEM, N2 physisorption as well as XPS and subsequently tested for their photocatalytic activities in the selective transformation of...

164

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

165

Intelligent design and selection of natural gas two-phase separators  

Microsoft Academic Search

Proper design of separators for surface production facilities is essential in order to maintain the quality and quantity of produced hydrocarbon fluids and avoid major operational problems in downstream equipment. Separators that are not properly sized or built will invariably be involved in operational mishaps encountered in natural gas surface operations and processing. This study addresses the basis of two-phase

Doruk Alp; Mohamad Al-Timimy

2009-01-01

166

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

PubMed

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

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

2005-06-01

167

Fort St. Vrain graphite site mechanical separation concept selection. Final report  

SciTech Connect

One of the alternatives to the disposal of the Fort St. Vrain (FSV) reactor spent nuclear fuel involves the separation of the fuel rods composed of compacts from the graphite fuel block assembly. After the separation of these two components, the empty graphite fuel blocks would be disposed of as a low level waste (provided the appropriate requirements are met) and the fuel compacts would be treated as high level waste material. This report deals with the mechanical separation aspects concerning physical disassembly of the FSV graphite fuel element into the empty graphite fuel blocks and fuel compacts. This report recommends that a drilling technique is the preferred choice for accessing the, fuel channel holes and that each hole is drilled separately. This report does not cover any techniques or methods to separate the triso fuel particles from the graphite matrix of the fuel compacts.

Berry, S.M.

1993-09-01

168

Selective extraction of metal ions from aqueous phase to ionic liquids: a novel thermodynamic approach to separations.  

PubMed

The selective extraction of metals from aqueous mixtures has generally relied on the use of selective ionophores. We present an alternative strategy that exploits a recently developed approach to extraction into an ionic liquid phase, and show that a high degree of control over selectivity can be obtained by tuning the relative concentrations of extraction agents. A thermodynamic model for the approach is presented, and an experimental separation of strontium and potassium ions is performed. It is shown that tuning the concentrations of the species involved can shift the ratio of potassium to strontium in the ionic liquid phase from 4:1 to 3:4. This extraction is performed under mild conditions with relatively common reagents. The result is a proof-of-concept for a novel separations scheme that could have great importance in a wide range of technological applications. PMID:25155578

Janssen, Camiel H C; Sánchez, Antonio; Kobrak, Mark N

2014-11-10

169

Mining of Uranium in Kazakhstan  

Microsoft Academic Search

\\u000a Approximately one-fifth of the world uranium reserves are found in Kazakhstan. Deposits are divided among six uranium ore\\u000a provinces according to geological positions, generic features and territorial location. Characteristics of uranium mineralization\\u000a of deposits are given. In-situ leaching (ISL) technology of uranium recovery from low-grade ore of sand-stone deposits is\\u000a given and based on selective dissolving of uranium bearing minerals.

Gulzhan Ospanova; Ivan Mazalov; Zhaksylyk Alybayev

170

Pervaporation & Vapor Permeation Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures  

EPA Science Inventory

Pervaporation and vapor permeation are membrane-based processes which have been proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol or butanol recovery from dilute fermentation broths, solvent/biofu...

171

Pervaporation and Vapor Permeation Tutorial: Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures  

EPA Science Inventory

Pervaporation and vapor permeation are membrane-based processes proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol or butanol recovery from fermentation broths, solvent/biofuel dehydration to meet ...

172

Selective Separation of r3 792 pdF PET from PVC for Plastics Recycling  

E-print Network

A new technology is usrngfrothflotation to separate PET from PVC for plastics recycling. Because of the simplicity of the process and low price of the reagent used, the technology requires low capital investment and low operating cost.

Joey Yang

173

Selective Separation of Trivalent Actinides from Lanthanides by Aqueous Processing with Introduction of Soft Donor Atoms  

SciTech Connect

With increased application of MOX fuels and longer burnup times for conventional fuels, higher concentrations of the transplutonium actinides Am and Cm (and even heavier species like Bk and Cf) will be produced. The half-lives of the Am isotopes are significantly longer than those of the most important long-lived, high specific activity lanthanides or the most common Cm, Bk and Cf isotopes, thus the greatest concern as regards long-term radiotoxicity. With the removal and transmutation of Am isotopes, radiation levels of high level wastes are reduced to near uranium mineral levels within less than 1000 years as opposed to the time-fram if they remain in the wastes.

Kenneth L. Nash; Sue B. Clark; Gregg Lumetta

2009-09-23

174

Uranium extraction process  

SciTech Connect

Uranium is extracted from wet process phosphoric acid by extraction with a mixture of a diorganophosphate and a neutral phosphorus compound, which is preferably a triorgano phosphine oxide, in the presence of nitrate to form an organic extract layer containing uranium and an aqueous acid layer, which are separated.

Rose, M.A.

1983-05-03

175

Uranium industry annual 1995  

SciTech Connect

The Uranium Industry Annual 1995 (UIA 1995) provides current statistical data on the U.S. uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1995 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. It contains data for the period 1986 through 2005 as collected on the Form EIA-858, ``Uranium Industry Annual Survey``. Data collected on the ``Uranium Industry Annual Survey`` provide a comprehensive statistical characterization of the industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1995, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. Data on uranium raw materials activities for 1986 through 1995 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2005, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. The methodology used in the 1995 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. For the reader`s convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix D along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 14 figs., 56 tabs.

NONE

1996-05-01

176

Hydrogen Selective Inorganic membranes for Gas Separations under High Pressure Intermediate Temperature Hydrocarbonic Envrionment  

SciTech Connect

In this project, we have successfully developed a full scale commercially ready carbon molecular sieve (CMS) based membrane for applications in H{sub 2} recovery from refinery waste and other aggressive gas streams. Field tests at a refinery pilot plant and a coal gasification facility have successfully demonstrated its ability to recovery hydrogen from hydrotreating and raw syngas respectively. High purity H{sub 2} and excellent stability of the membrane permeance and selectivity were obtained in testing conducted over >500 hours at each site. The results from these field tests as well as laboratory testing conclude that the membranes can be operated at high pressures (up to 1,000 psig) and temperatures (up to 300 C) in presence of aggressive contaminants, such as sulfur and nitrogen containing species (H{sub 2}S, CO{sub 2}, NH{sub 3}, etc), condensable hydrocarbons, tar-like species, heavy metals, etc. with no observable effect on membrane performance. By comparison, similar operating conditions and/or environments would rapidly destroy competing membranes, such as polymeric, palladium, zeolitic, etc. Significant cost savings can be achieved through recovering H{sub 2} from refinery waste gas using this newly developed CMS membrane. Annual savings of $2 to 4MM/year (per 20,000 scfd of waste gas) can be realized by recovering the H{sub 2} for reuse (versus fuel). Projecting these values over the entire US market, potential H{sub 2} savings from refinery waste gases on the order of 750 to 1,000MM scfd and $750 to $1,000MM per year are possible. In addition to the cost savings, potential energy savings are projected to be ca. 150 to 220 tBTU/yr and CO{sub 2} gas emission reductions are projected to be ca. 5,000 to 6,500MMtons/year. The full scale membrane bundle developed as part of this project, i.e., 85 x 30 inch ceramic membrane tubes packaged into a full ceramic potting, is an important accomplishment. No comparable commercial scale product exists in the inorganic membrane field. Further, this newly developed full scale bundle concept can be extended to other thin film inorganic membrane technology (Pd, zeolite, etc), providing a potential commercialization pathway for these membrane materials that demonstrate high potential in a variety of separation applications yet remain a laboratory 'novelty' for lack of a full scale support. Overall, the project has been highly successful and all of the project objectives have been met. We have developed the first of its kind commercial scale carbon molecular sieve membrane and demonstrated its performance in field testing under aggressive operating conditions and in the presence of chemical contaminants that would rapidly destroy alternative organic and inorganic membranes. This innovative membrane permits H{sub 2} recovery from gas streams that up until now have not been successfully treated with membrane or conventional technology. Our end user participant is currently pursuing the field demonstration of this membrane for hydrogen recovery at its refinery site.

Rich Ciora; Paul KT Liu

2012-06-27

177

Solvent selection for cyclohexane-cyclohexene-benzene separation by extractive distillation using non-steady-state gas chromatography  

SciTech Connect

The infinite-dilution activity coefficients of cyclohexane, cyclohexene, and benzene in N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, phenyl acetate, and dimethyl malonate have been determined at temperatures ranging from 40 to 80 C, by non-steady-state gas chromatography. From these data, the limiting selectivity-solvency properties for cyclohexane-benzene, cyclohexene-benzene, and cyclohexane-cyclohexene, in the presence of the aforementioned solvents, are studied, and the solvents tested are considered for the cyclohexane-cyclohexene-benzene separation by extractive distillation. According to the results, N,N-dimethylacetamide seems to be an adequate solvent for the cyclohexane-benzene and cyclohexene-benzene separations. The separation of cyclohexane-cyclohexene is the most difficult, in spite of the difference of boiling points, much higher than for cyclohexane-benzene.

Vega, A.; Diez, F.; Esteban, R.; Coca, J. [Univ. of Oviedo (Spain). Dept. of Chemical and Environmental Engineering] [Univ. of Oviedo (Spain). Dept. of Chemical and Environmental Engineering

1997-03-01

178

Understanding the anomalous alkane selectivity of ZIF-7 in the separation of light alkane/alkene mixtures.  

PubMed

C2 and C3 alkanes are selectively adsorbed from mixtures over the corresponding alkenes on the zeolite imidazolate framework ZIF-7 through a gate-opening mechanism. As a result, the direct production of the pure alkene upon adsorption and the pure alkane upon desorption in packed columns is possible. Herein, a detailed investigation of the step-wise adsorption and separation of alkanes and alkenes is presented, together with a rigorous performance assessment. A molecular picture of the gate-opening mechanism underlying the unprecedented selectivity towards alkane adsorption is proposed based on DFT calculations and a thermodynamic analysis of the adsorption-desorption isotherms. PMID:21755546

van den Bergh, Johan; Gücüyener, Canan; Pidko, Evgeny A; Hensen, Emiel J M; Gascon, Jorge; Kapteijn, Freek

2011-08-01

179

Investigation of thermal treatment on selective separation of post consumer plastics prior to froth flotation.  

PubMed

Plastics have become the widely used materials because of their advantages, such as cheapness, endurance, lightness, and hygiene. However, they cause waste and soil pollution and they do not easily decompose. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. Depending on their surface characteristics, these plastics can be separated from each other by flotation method which is useful mineral processing technique with its low cost and simplicity. The main objective of this study is to investigate the flotation characteristics of PET and PVC and determine the effect of plasticizer reagents on efficient plastic separation. For that purpose, various parameters such as pH, plasticizer concentration, plasticizer type, conditioning temperature and thermal conditioning were investigated. As a result, PET particles were floated with 95.1% purity and 65.3% efficiency while PVC particles were obtained with 98.1% purity and 65.3% efficiency. PMID:23747135

Guney, Ali; Poyraz, M Ibrahim; Kangal, Olgac; Burat, Firat

2013-09-01

180

Evaluation of Egorov's improved separate solution method for determination of low selectivity coefficients by numerical simulation.  

PubMed

The group of Egorov has recently proposed an elegant method to determine unbiased selectivity coefficients of ion-selective electrodes (Egorov et al. Anal. Chem. 2014, 86, 3693). Once the electrode is exposed to a solution containing only interfering ions, the time-dependent experimental selectivity coefficients are plotted as a function of the inverse fourth root of time and extrapolated to zero. The principal assumption of the approach is the progression of the diffusion layer in the membrane phase with square root of time. This letter critically evaluates the usefulness of this methodology by finite element analysis. The results suggest that the improvement of observed selectivity values are highly significant for an initially uniform distribution of primary ions across the membrane, strongly supporting the methodology. When strong inward ion fluxes of primary ions are present instead, a modification of the method by extrapolation of logarithmic selectivity coefficients appears to give the best results. PMID:25098967

Bakker, Eric

2014-08-19

181

300 AREA URANIUM CONTAMINATION  

SciTech Connect

{sm_bullet} Uranium fuel production {sm_bullet} Test reactor and separations experiments {sm_bullet} Animal and radiobiology experiments conducted at the. 331 Laboratory Complex {sm_bullet} .Deactivation, decontamination, decommissioning,. and demolition of 300 Area facilities

BORGHESE JV

2009-07-02

182

Selectivity enhancement in tritium isotope separation by multiple frequency multiple photon dissociation of the CTF 3 \\/CHF 3 System  

Microsoft Academic Search

Isotope separation of tritium by multiple photon dissociation process in multiple frequency fields of a TEA-CO2 laser is reported for the first time. A ten-fold improvement in the bulk selectivity was obtained in 8.5 Torr CTF3\\/CHF3 in the presence of buffer gas at room temperature using 9R(8) to 9R(14) CO2 laser lines compared to single frequency excitation. Investigations of various

R. S. Karve; A. K. Nayak; S. K. Sarlar; K. V. S. Rama Rao; J. P. Mittal

1989-01-01

183

Weak affinity ligands selection using quartz crystal microbalance biosensor: multi-hydroxyl amine ligands for protein separation.  

PubMed

Multi-hydroxyl amines including tris(hydroxymethyl)aminomethane (Tris), serinol and ethanolamine were selected as weak affinity ligands using a rapid screening by quartz crystal microbalance (QCM) biosensor. Based on the specific recognition between the ligands and two proteins, lysozyme (LZM) and cytochrome c (Cyt c), a weak affinity chromatography method was developed for specific separation of the two proteins. The frontal analysis results showed that the apparent dissociation constants (K(D)) of ligand-protein complexes were all in the order of weak affinity (10(-4) M). By weak affinity columns modified with the three multi-hydroxyl amines individually, LZM and Cyt c were baseline separated as retarded peaks from non-specific protein and each other in a single cycle of loading and eluting. Moreover, the Tris-modified column typically showed the satisfactory repeatability and stability as a new type of weak affinity columns. The present strategy composed of QCM selecting and affinity chromatography separating was promising to extend the variety of weak affinity ligands and develop inexpensive specific affinity methods for separation and purification of multiple proteins on one single column. PMID:21889642

Cao, Qing; Yin, Yueyan; Quan, Li; Li, Na; Li, Kean; Liu, Feng

2011-10-10

184

Selection of distinct populations of dentate granule cells in response to inputs as a mechanism for pattern separation in mice  

PubMed Central

The hippocampus is critical for episodic memory and computational studies have predicted specific functions for each hippocampal subregion. Particularly, the dentate gyrus (DG) is hypothesized to perform pattern separation by forming distinct representations of similar inputs. How pattern separation is achieved by the DG remains largely unclear. By examining neuronal activities at a population level, we revealed that, unlike CA1 neuron populations, dentate granule cell (DGC) ensembles activated by learning were not preferentially reactivated by memory recall. Moreover, when mice encountered an environment to which they had not been previously exposed, a novel DGC population—rather than the previously activated DGC ensembles that responded to past events—was selected to represent the new environmental inputs. This selection of a novel responsive DGC population could be triggered by small changes in environmental inputs. Therefore, selecting distinct DGC populations to represent similar but not identical inputs is a mechanism for pattern separation. DOI: http://dx.doi.org/10.7554/eLife.00312.001 PMID:23538967

Deng, Wei; Mayford, Mark; Gage, Fred H

2013-01-01

185

Use of ligand-modified micellar-enhanced ultrafiltration to selectively separate copper ions from wastewater streams  

SciTech Connect

The selective removal of target ions from an aqueous solution containing ions of like charge by ligand-modified micellar-enhanced ultrafiltration (LM-MEUF), is presented. In LM-MEUF, surfactant and specially tailored ligand are added to the contaminated stream. The surfactant forms aggregates called micelles, the hydrocarbon core of which the ligand complexed with the target species will solubilize. The surfactant is chosen to have the same charge type as the target ion; therefore, other ions (with similar charge) will not associate with the micelle, which makes the separation of the target ion selective. The solution is then processed by ultrafiltration, using a membrane with pore size small enough to block the passage of the micelles. In this study the divalent copper is the target ion in the solution containing divalent calcium. The surfactant is cetylpyridinium chloride (CPC) and the ligand is 4-hexadecyloxybenzyliminodiacetic acid (C{sub 16}BIDA). Experiments were conducted with batch stirred cells and the results have been compared to separation that take place under a variety of conditions in the LM-MEUF process. Rejections of copper of up to 99.8% are observed, with almost no rejection of calcium, showing that LM-MEUF has excellent selectivity and separation efficiency.

Shadizadeh, S.B.

1992-12-31

186

Effect of chromatographic conditions on the separation and system efficiency for HPLC of selected alkaloids on different stationary phases.  

PubMed

Retention parameters of alkaloid standards were determined on different stationary phases, i.e., octadecyl silica, base-deactivated octadecyl silica, cyanopropyl silica, preconditioned cyanopropyl silica, and pentafluorophenyl, using different aqueous eluant systems: acetonitrile-water mixtures; buffered aqueous mobile phases at pH 3 or 7.8; and aqueous eluants containing ion-pairing reagents (octane-1-sulfonic acid sodium salt and pentane-1-sulfonic acid sodium salt) or silanol blockers (tetrabutyl ammonium chloride and diethylamine). Improved peak symmetry and separation selectivity for basic solutes was observed when basic buffer, ion-pairing reagents, and, especially, silanol blockers as mobile phase additives were applied. The best separation selectivity and most symmetric peaks for the investigated alkaloids were obtained in systems containing diethylamine in the mobile phase. The influence of acetonitrile concentration and kind and concentration of ion-pairing reagents or silanol blockers on retention, peak symmetry, and system efficiency was also examined. The most efficient and selective systems were used for separation of the investigated alkaloids and analysis of Fumaria officinalis and Glaucium flavum plant extracts. PMID:21391483

Petruczynik, Anna

2011-01-01

187

Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method  

Microsoft Academic Search

More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste

F?rat Burat; Ali Gueney; M. Olgaç Kangal

2009-01-01

188

Selective separation and purification of highly polar basic compounds using a silica-based strong cation exchange stationary phase.  

PubMed

Compared to moderately and weakly hydrophilic bases, highly polar basic compounds are even more difficult to separate due to their poor retention in reversed phase (RP) mode. This study described the successful applications of a strong cation exchange (SCX) stationary phase to achieve symmetric peak shape, adequate retention and selectivity in the separation of very polar basic compounds. Salt and acetonitrile concentrations were adjusted to optimize the separation. Good correlations (R(2)=0.998-1.000) between the logarithm of the retention factor and the logarithm of salt or acetonitrile concentration were obtained. Gradients generated by changing salt or acetonitrile concentration were compared for the analysis of different highly polar bases. Although all of the analytes were eluted more quickly with an acetonitrile gradient, the effect of the gradients tested on peak width and peak shape varied with respect to analyte. In addition, the effects of different types of cation and anion additives were also investigated. After separation parameters were acquired, the SCX-based method was utilized to analyze highly hydrophilic alkaloids from Scopolia tangutica Maxim with high separation efficiency (plate numbers>32,000 m(-1)). Concurrently, one very polar alkaloid fraction was purified with symmetric peak shape using the current method. Our results suggest that SCX stationary phase can be used as an alternative to RP stationary phase in the analysis and purification of highly hydrophilic basic compounds. PMID:24267097

Long, Zhen; Guo, Zhimou; Xue, Xingya; Zhang, Xiuli; Nordahl, Lilly; Liang, Xinmiao

2013-12-01

189

Combination of solid phase extraction and dispersive liquid-liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination.  

PubMed

A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid-liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L(-1)) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid-liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L(-1), and a relative standard deviation of 4.1% (n=6) at 400 ng L(-1) were obtained. The method was successfully applied to the determination of uranium in mineral water, river water, well water, spring water and sea water samples. PMID:24231318

Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

2013-12-15

190

High-Dimensional Gaussian Graphical Model Selection: Walk Summability and Local Separation Criterion  

E-print Network

We consider the problem of high-dimensional Gaussian graphical model selection. We identify a set of graphs for which an efficient estimation algorithm exists, and this algorithm is based on thresholding of empirical ...

Willsky, Alan S.

191

Uranium purchases report 1992  

SciTech Connect

Data reported by domestic nuclear utility companies in their responses to the 1991 and 1992 ``Uranium Industry Annual Survey,`` Form EIA-858, Schedule B ``Uranium Marketing Activities,are provided in response to the requirements in the Energy Policy Act 1992. Data on utility uranium purchases and imports are shown on Table 1. Utility enrichment feed deliveries and secondary market acquisitions of uranium equivalent of US DOE separative work units are shown on Table 2. Appendix A contains a listing of firms that sold uranium to US utilities during 1992 under new domestic purchase contracts. Appendix B contains a similar listing of firms that sold uranium to US utilities during 1992 under new import purchase contracts. Appendix C contains an explanation of Form EIA-858 survey methodologies with emphasis on the processing of Schedule B data.

Not Available

1993-08-19

192

Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates.  

PubMed

The potential of microcristaline cellulose as sorbent in the separation of eight compounds: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin gallate (EGCg), procyanidin B1 and procyanidin B2 was studied. Cellulose HPTLC plates prewashed in water (not necessary, when water was used as developing solvent) and dried with a hair dryer, bandwise application and development in horizontal developing chamber (sandwich configuration) gave the best results. Detection was performed using vanillin-H3PO4 reagent. Four new developing solvent systems were proposed: water, 1-propanol-water (20:80, v/v), 1-propanol-water-acetic acid (4:2:1, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v), and at least two of them were needed for the differentiation between all eight compounds. Surprisingly, water enabled the separation of epimers C from EC and GC from EGC, as well as the dimers procianidin B1 and B2. Additionally, C, EGC, B1 and B2 were separated from all the other compounds. The best choice for developing solvent is given for each of the studied compounds. The best separation of the five main catechins (EC, GC, EGC, ECg, EGCg) present in green tea extract was achieved using 1-propanol-water-acetic acid (20:80:1, v/v). The chromatograms of oak bark extract developed in solvents with higher water content (1-propanol-water (1:4, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v)) showed less bands than chromatograms developed in solvents with higher organic modifier content (e.g. 1-propanol-water-acetic acid (4:2:1, v/v)). It was proved that such behavior was due to the presence of procyanidins beside the main component catechin. PMID:16001555

Vovk, Irena; Simonovska, Breda; Vuorela, Heikki

2005-06-10

193

Modified cyclodextrin polymers as selective ion carriers for Pb(II) separation across plasticized membranes  

Microsoft Academic Search

In the present work the hydrophobic ?-cyclodextrin (?-CD) polymers have been used as macrocyclic ion carriers for separation of Pb(II), Zn(II), and Cu(II) ions from dilute aqueous solutions by transport across polymer inclusion membranes. The ?-CD polymers were prepared by cross-linking of ?-CD with 2-(1-docosenyl)-succinic anhydride derivatives in anhydrous N,N-dimethylformamide in the presence of NaH. The metal ions were transported

Cezary A. Kozlowski; Wladys?aw Walkowiak; Tomasz Girek

2008-01-01

194

Selective separation of ferric and non-ferric forms of human transferrin by capillary micellar electrokinetic chromatography.  

PubMed

The previously published method allowing the separation of non-ferric (iron-free) and ferric (iron-saturated) forms of human serum transferrin via capillary electrophoresis has been further developed. Using a surface response methodology and a three-factorial Doehlert design we have established a new optimized running buffer composition: 50mM Tris-HCl, pH 8.5, 22.5% (v/v) methanol, 17.5mM SDS. As a result, two previously unobserved monoferric forms of protein have been separated and identified, moreover, the loss of ferric ions from transferrin during electrophoretic separation has been considerably reduced by methanol, and the method selectivity has been yet increased resulting in a total separation of proteins exerting only subtle or none difference in mass-to-charge ratio. The new method has allowed us to monitor the gradual iron saturation of transferrin by mixing the iron-free form of protein with the buffers with different concentrations of ferric ions. It revealed continuously changing contribution of monoferric forms, characterized by different affinities of two existing iron binding sites on N- and C-lobes of protein, respectively. Afterwards, the similar experiment has been conducted on-line, i.e. inside the capillary, comparing the effectiveness of two possible modes of the reactant zones mixing: diffusion mediated and electrophoretically mediated ones. Finally, the total time of separation has been decreased down to 4min, taking the advantage from a short-end injection strategy and maintaining excellent selectivity. PMID:24690308

Nowak, Pawe?; ?piewak, Klaudyna; Nowak, Julia; Brindell, Ma?gorzata; Wo?niakiewicz, Micha?; Stochel, Gra?yna; Ko?cielniak, Pawe?

2014-05-01

195

Selective comprehensive multi-dimensional separation for resolution enhancement in high performance liquid chromatography. Part I: principles and instrumentation.  

PubMed

An approach to enhancing the resolution of select portions of conventional one-dimensional high performance liquid chromatography (HPLC) separations was developed, which we refer to as selective comprehensive two-dimensional HPLC (sLC×LC). In this first of a series of two papers we describe the principles of this approach, which breaks the long-standing link in on-line multi-dimensional chromatography between the timescales of sampling the first dimension (¹D) separation and the separation of fractions of ¹D effluent in the second dimension. This allows rapid, high-efficiency separations to be used in the first dimension, while still adequately sampling ¹D peaks. Transfer, transient storage, and subsequent second dimension (²D) separations of multiple fractions of a particular ¹D peak produces a two-dimensional chromatogram that reveals the coordinates of the peak in both dimensions of the chromatographic space. Using existing valve technology we find that the approach is repeatable (%RSD of peak area <1.5%), even at very short first dimension sampling times--as low as 1s. We have also systematically studied the critical influence of the volume and composition of fractions transferred from the first to the second dimension of the sLC × LC system with reversed-phase columns in both dimensions, and the second dimension operated isocratically. We find that dilution of the transferred fraction, so that it contains 10-20% less organic solvent than the ²D eluent, generally mitigates the devastating effects of large transfer volumes on ²D performance in this type of system. Several example applications of the sLC × LC approach are described in the second part of this two-part series. We anticipate that future advances in the valve technology used here will significantly widen the scope of possible applications of the sLC × LC approach. PMID:21802089

Groskreutz, Stephen R; Swenson, Michael M; Secor, Laura B; Stoll, Dwight R

2012-03-01

196

Ethane selective IRMOF-8 and its significance in ethane-ethylene separation by adsorption.  

PubMed

The separation of ethylene from ethane is one of the most energy-intensive single distillations practiced. This separation could be alternatively made by an adsorption process if the adsorbent would preferentially adsorb ethane over ethylene. Materials that exhibit this feature are scarce. Here, we report the case of a metal-organic framework, the IRMOF-8, for which the adsorption isotherms of ethane and ethylene were measured at 298 and 318 K up to pressures of 1000 kPa. Separation of ethane/ethylene mixtures was achieved in flow experiments using a IRMOF-8 filled column. The interaction of gas molecules with the surface of IRMOF-8 was explored using density functional theory (DFT) methods. We show both experimentally and computationally that, as a result of the difference in the interaction energies of ethane and ethylene in IRMOF-8, this material presents the preferential adsorption of ethane over ethylene. The results obtained in this study suggest that MOFs with ligands exhibiting high aromaticity character are prone to adsorb ethane preferably over ethylene. PMID:25010787

Pires, João; Pinto, Moisés L; Saini, Vipin K

2014-08-13

197

pH dependent separation of uranium by chelation chromatography using pyridine 2,6-dimethanol as a chelator: single crystal X-ray structural confirmation of the chelated uranium complex.  

PubMed

A very effective sorbent material which exhibits exceptional capture of hexavalent uranium from other actinides and lanthanides at microg g(-1) level, features pyridine 2,6-dimethanol immobilized onto alumina. The maximum sorption capacity for dioxouranium(VI) was found as 1.96 mmol g(-1) at pH 3.0. The adsorbed uranium complex was eluted completely by 0.05 mol L(-1) (NH(4))(2)CO(3) solution and the concentration of hexavalent dioxouranium ion was monitored spectrophotometrically using Arsenazo III. The structure of the chelated uranium complex has been confirmed by single crystal X-ray structure analysis and Fourier transform infrared red (FTIR) spectroscopy. Thermo gravimetric analysis/differential thermo gravimetric analysis (TGA/DTG) of the chelated uranium complex was performed. The method is reproducible with a relative standard deviation (RSD) of 1.2% (N=10) and the three sigma detection limits (N=15) 1.2 microg mL(-1) respectively. A pre-concentration factor, almost 500, for uranium was achieved. Interferences from Th(4+), Mn(2+), Ni(2+) and Cu(2+) ions were masked with ethylene diamine tetra acetic acid (di-sodium salt) (Na(2)EDTA) in the aqueous phase. The developed method has been tested for uranium recovery and estimation in some certified reference materials and environmental samples. PMID:20510512

Saha, Raja; Das, Sudipta; Banerjee, Arnab; Sahana, Animesh; Sudarsan, M; Slawin, A M Z; Li, Yang; Das, Debasis

2010-09-15

198

Control of selectivity via nanochemistry: monolithic capillary column containing hydroxyapatite nanoparticles for separation of proteins and enrichment of phosphopeptides.  

PubMed

New monolithic capillary columns with embedded commercial hydroxyapatite nanoparticles have been developed and used for protein separation and selective enrichment of phosphopeptides. The rod-shaped hydroxyapatite nanoparticles were incorporated into the poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) monolith by simply admixing them in the polymerization mixture followed by in situ polymerization. The effect of percentages of monomers and hydroxyapatite nanoparticles in the polymerization mixture on the performance of the monolithic column was explored in detail. We found that the loading capacity of the monolith is on par with other hydroxyapatite separation media. However, the speed at which these columns can be used is higher due to the fast mass transport. The function of the monolithic columns was demonstrated with the separations of a model mixture of proteins including ovalbumin, myoglobin, lysozyme, and cytochrome c as well as a monoclonal antibody and its aggregates with protein A. Selective enrichment and MALDI/MS characterization of phosphopeptides fished-out from complex peptide mixtures of ovalbumin, ?-casein, and ?-casein digests were also achieved using the hydroxyapatite monolith. PMID:20806887

Krenkova, Jana; Lacher, Nathan A; Svec, Frantisek

2010-10-01

199

Selection of a hydride former for the separation of hydrogen isotopes from inerts  

SciTech Connect

The properties of four hydride-forming materials have been investigated to determine their applicability for use in a process to separate hydrogen isotopes from inerts. These materials are Zr{sub 0.8}Ti{sub 0.2}Ni, Zr{sub 0.65}Ti{sub 0.35}Co, NdCo{sub 3}, and ErFe{sub 2}. The properties investigated while surveying these materials include ease of activation, isotherm characteristics, kinetics, cycling stability, and oxygen stability. The results of the survey indicate NdCo{sub 3} to be the hydride former of choice for use in the inert separation process. It is the most easily activated and has the most favorable isotherm characteristics (the largest usable capacity, flat plateaux, small hysteresis, and negligible heel) as well as the fastest absorption kinetics of the materials tested. NdCo{sub 3} also has good cycling and oxygen stability. As with most intermetallic alloys NdCo{sub 3} decrepitates into a fine powder after only a few sorption cycles in hydrogen and therefore must be consolidated in order to be used in the fixed-bed absorber envisioned for the inert separation process. Consolidation was achieved through support of the NdCo{sub 3} in a sinter-bonded aluminum matrix. Stable compacts of NdCo{sub 3} have been made consisting of 40 wt % Al in NdCo{sub 3} pellets, pressed at 27 kpsi, sintered under vacuum for 2 hr at 450{degree}C. These compacts retained the full absorptive capacity of NdCo{sub 3} and remained 99 wt % intact after 15 sorption cycles in protium. 16 refs., 9 figs.

Fisher, I.A.

1990-01-01

200

Reversed phase extraction chromatographic separation of scandium with amberlite LA-1 from malonate solutions  

SciTech Connect

Scandium was extracted at pH 5.0 from 0.01 M malonic acid on silica gel column impregnated with Amberlite LA-1. Nickel, zinc, cadmium, mercury, lead, tin, aluminium, and lanthanum in binary mixtures passed through the cadmium because they could not form malonato complexes. It was separated by the process of selective elution from elements such as zirconium, thorium, uranium, iron(III), gallium, indium, cerium(III), and titanium by exploiting difference in stability of malonato complexes. Scandium was separated from multicomponent mixture containing yttrium, titanium, zirconium, thorium, uranium and aluminium by a process of selective sorbtion and selective elution.

Narayanan, P.; Khopkar, S.M.

1983-01-01

201

Selective Separation and Determination of Copper and Gold in Gold Alloy Using Ion Exchange Polyurethane Foam  

Microsoft Academic Search

A sensitive and selective determination of copper and gold in gold alloys was achieved using a strong anion exchange polyurethane foam (PUFIX) and polyurethane foam after hydrolysis (white?PUF). The total sorption capacity of the resin was 4.22 and 0.85 mmol g for copper and gold, respectively. The maximum sorption of Cu (II) and Au (III) were in 0.02–0.2 and 0.06 M HCl, respectively.

E. A. Moawed; N. Burham

2007-01-01

202

Selective separation of Cr(III) and Fe(III) from liquid effluents using a chelating resin.  

PubMed

This study aimed to assess the selective separation of Cr(III) from Fe(III) from liquid solutions by using a chelating ion exchange resin, Diaion CR 11, from Mitsubishi Chemical Corporation, in the H(+) form. Equilibrium experiments with synthetic solutions of iron and chromium were carried out in batch mode. For both metals favorable adsorption isotherms were obtained, and the experimental data were well described by the Langmuir model. However, the resin exhibited higher affinity for iron than for chromium. The regeneration experiments revealed that, for both metals, HCl provided higher removal efficiencies than H(2)SO(4) and HNO(3). Moreover, precipitation with NaOH allows selectively separate chromium and iron to be stripped from the resin. Experiments in fixed bed operation were carried out to assess the dynamic behavior of the sorption of Cr(III) and Fe(III) into the tested resin by using synthetic and industrial solutions. The experiments with industrial effluent showed that the resin can remove low levels of contaminant transition metal ions, and thus the effluent can be purified for reuse of chromium during periods of 20-25 min. The resin regeneration was achieved with a sequential treatment with HCl and NaOH/H(2)O(2). High efficiencies were observed for both monocomponent and multicomponent systems. A global strategy for separating and recovering Cr(III) from an effluent that also contains Fe(III) is presented, involving the integration of ion exchange (saturation and regeneration phases) and precipitation processes. In conclusion, our approach demonstrates that efficient separation of chromium and iron is possible if ion exchange operation in a fixed bed configuration is optimized and combined with conventional processes such as precipitation. PMID:22925871

Fernandes, Sandra; Romão, Inês S; Abreu, Carlos M R; Quina, Margarida J; Gando-Ferreira, Licínio M

2012-01-01

203

Ion imprinted polymeric nanoparticles for selective separation and sensitive determination of zinc ions in different matrices.  

PubMed

Preparation of Zn(2+) ion-imprinted polymer (Zn-IIP) nanoparticles is presented in this report. The Zn-IIP nanoparticles are prepared by dissolving stoichiometric amounts of zinc nitrate and selected chelating ligand, 3,5,7,20,40-pentahydroxyflavone, in 15 mL ethanol-acetonitrile (2:1; v/v) mixture as a porogen solvent in the presence of ethylene glycol-dimethacrylate (EGDMA) as cross-linking, methacrylic acid (MAA) as functional monomer, and 2,2-azobisisobutyronitrile (AIBN) as initiator. After polymerization, Cavities in the polymer particles corresponding to the Zn(2+) ions were created by leaching the polymer in HCl aqueous solution. The synthesized IIPs were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal analysis techniques. Also, the pH range for rebinding of Zn(2+) ion on the IIP and equilibrium binding time were optimized, using flame atomic absorption spectrometry. In selectivity study, it was found that imprinting results increased affinity of the material toward Zn(2+) ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIPs were repeatedly used and regenerated for six times without any significant decrease in polymer binding affinities. Finally, the prepared sorbent was successfully applied to the selective recognition and determination of zinc ion in different real samples. PMID:23981411

Shamsipur, Mojtaba; Rajabi, Hamid Reza; Pourmortazavi, Seied Mahdi; Roushani, Mahmoud

2014-01-01

204

Molecular imprinting-based separation methods for selective analysis of fluoroquinolones in soils.  

PubMed

Molecularly imprinted polymers (MIPs) for fluoroquinolone antibiotics (FQs) have been synthesised in one single preparative step by precipitation polymerisation using ciprofloxacin (CIP) as template. Combinations of methacrylic acid (MAA) or 4-vinylpyridine (VP) as functional monomers, ethylene glycol dimethacrylate as crosslinker and dichloromethane, methanol, acetonitrile or toluene as porogens were tested. The experiments carried out by molecularly imprinted solid-phase extraction (MISPE) in cartridges did not allow to detect any imprint effect in the VP-based polymers whereas it was clearly observed in the MAA-based polymers. Among them, the MIP prepared in methanol using MAA as monomer showed the best performance and was chosen for further experiments. The ability of the selected MIP for the selective recognition of other widely used FQs (enoxacin, norfloxacin, danofloxacin and enrofloxacin) and quinolones (Qs) (cinoxacin, flumequine, nalidixic acid and oxolinic acid) was evaluated. The obtained results revealed the high selectivity of the obtained polymer, which was able to distinguish between FQs, that were recognised and retained onto the MIP cartridge, and Qs, which were washed out during loading and washing steps. The MIP was then packed into a stainless steel column (50mmx4.6mm i.d.) and evaluated as chromatography column for screening of FQs in soil samples. The mobile phase composition, flow rate, and the elution profile were then optimised in order to improve peak shape without sacrifying imprinting factor. Finally, under optimised conditions, soil samples spiked with CIP or with a mixture of fluoroquinolones in concentration of 0.5microgg(-1) were successfully analysed by the developed MIP-based procedures. PMID:17961582

Turiel, Esther; Martín-Esteban, Antonio; Tadeo, José Luis

2007-11-23

205

Selectivity Sequence of Multivalent Lanthanides for Their Separation on Antimonate Based Exchangers  

Microsoft Academic Search

The adsorption of trivalent lanthanide ions, Ln (La, Pr, Nd, Gd, and Er), using two antimonate based exchangers, namely, silicon antimonate (SiSb) and poly(acrylamide titanium antimonate), PAmTA, was studied from their nitrate solutions at pH 3.5 ± 0.1. The formation constants in Ln\\/SiSb and Ln\\/PAmTA systems, logKS1 and logKS2, were calculated for the above mentioned lanthanides. The Kd values of the selected

G. M. Ibrahim; M. I. Ahmad; B. El-Gammal; I. M. El-Naggar

2011-01-01

206

Thermal band selection for the PRISM instrument: 1. Analysis of emissivity-temperature separation algorithms  

NASA Astrophysics Data System (ADS)

One of the missions being planned by the European Space Agency (ESA) within the framework of its Earth Observation Programme is the Processes Research by Imaging Space Mission (PRISM). The PRISM instrument consists of a thermal sensor whose main objective is to retrieve accurate land surface temperatures (LST) and whose band positions are 3.5-4.1 ?m, 8.1-9.5 ?m, 10.3-11.3 ?m, and 11.5-12.5 ?m. We have studied the optimal design of this instrument to retrieve accurate LSTs. First, we have analyzed several emissivity-temperature separation methods (part 1) and atmospheric and emissivity correction algorithms (part 2). Finally, we have identified the optimal band configuration (part 3). This paper is the first of a series of three and addresses the question of the emissivity-temperature separability. Among all the existing algorithms, we have studied the "absolute methods," which are able to estimate the absolute value of emissivity at satellite scale and can yield better results in the emissivity estimate. These methods are the algorithm based on the temperature-independent thermal infrared spectral index (TISI), the alpha coefficients method, and the algorithms which use visible, near-infrared, and shortwave infrared data to estimate the thermal emissivity (vegetation cover method (VCM)). The study consisted of an analysis of both random and systematic errors of each method. The results indicate that emissivity can be obtained with an error of ±1.7-5% using the alpha coefficients, ±1.7-3% using the TISIs, and ±0.5-1.4% using the VCM, depending on the spectral region. In all cases the error decreases with wavelength, and the lowest errors are achieved in the 10-12 ?m spectral region, due to small variability of emissivity. It is necessary that the two first methods use radiosondes simultaneous with the satellite overpass to perform the atmospheric corrections on the thermal data; in addition, they show important sources of systematic errors, which will increase the uncertainty in the emissivity estimate (even in the best possible case). The VCM does not use radiosondes and does not present important sources of systematic error. It appears to be the procedure with the most favorable error propagation characteristics. Thus the VCM could be the most adequate method for retrieving the land surface emissivity (LSE), within the framework of this work.

Caselles, Vicente; Valor, Enric; Coll, CéSar; Rubio, Eva

1997-05-01

207

WATER AND WASTEWATER POLISHING USING 3M SELECTIVE SEPARATION REMEDIATION CARTRIDGE TECHNOLOGY  

SciTech Connect

3M has developed technology for selectively removing trace levels of dissolved contaminant materials from liquids using systems operating at flow rates up to 50 gallons per minute. This technology combines active particle chemistries with a particle-loaded membrane to achieve a new medium for liquid waste processing--a spiral wound filter cartridge. This technology has shown success by generating high decontamination factors and reducing contaminants to part per trillion levels. The spiral wound cartridge offers simplified installation, convenient replacement, and clean, easy disposal of a concentrated waste. By incorporating small, high surface area particles (5 to 80 microns) into a sturdy, yet porous, membrane greater removal efficiencies of even trace contaminants can be achieved at higher flow rates than with conventional column systems. In addition, the captive-particle medium prevents channeling of liquids and insures uniform flow across the sorbing particle surface. The cartridges fit into standard, commercially-available housings and whole system capital costs are substantially lower than those of column or reverse osmosis systems. Developmental work at high degrees of water polishing have included removal of mercury from contaminated wastewater, various radionuclides from process water, and organometallic species from surface water discharges. Laboratory testing and on-site demonstration data of these applications show the levels of success that have been achieved thus far.

Hoffmann, K. M.; Scanlan, T. J.; Seely, D. C.

2002-02-25

208

Wide Angle, Single Screen, Gridded Square-Loop Frequency Selective Surface for Diplexing Two Closely Separated Frequency Bands  

NASA Technical Reports Server (NTRS)

The design and performance of a wide angle, single screen, frequency selective surface (FSS) with gridded square-loop path elements are described for diplexing closely separated signal bands, for example, X- and Ku-band signals in an Orbiting Very Long Baseline Interferometer (OVLBI) earth station reflector antenna system, as well as other applications such as military and commercial communications via satellites. Excellent agreement is obtained between the predicted and measured results of this FSS design using the gridded square-loop patch elements sandwiched between 0.0889 cm thick tetrafluoroethylene fluorocarbon polymer (PTFE) slabs. Resonant frequency drift is reduced by 1 GHz with an incidence angle from 0 deg normal to 40 deg from normal.

Wu, Te-Kao (Inventor)

1996-01-01

209

Evaluation of health risks associated with proposed ground water standards at selected inactive uranium mill-tailings sites  

SciTech Connect

The US Environmental Protection Agency (EPA) has proposed ground water standards applicable to all inactive uranium mill-tailings sites. The proposed standards include maximum concentration limits (MCL) for currently regulated drinking water contaminants, as well as the addition of standards for molybdenum, uranium, nitrate, and radium-226 plus radium-228. The proposed standards define the point of compliance to be everywhere downgradient of the tailings pile, and require ground water remediation to drinking water standards if MCLs are exceeded. This document presents a preliminary description of the Phase 2 efforts. The potential risks and hazards at Gunnison, Colorado and Lakeview, Oregon were estimated to demonstrate the need for a risk assessment and the usefulness of a cost-benefit approach in setting supplemental standards and determining the need for and level of restoration at UMTRA sites. 8 refs., 12 tabs.

Hamilton, L.D.; Medeiros, W.H.; Meinhold, A.; Morris, S.C.; Moskowitz, P.D.; Nagy, J.; Lackey, K.

1989-04-01

210

Mechanistic Investigation of Solvent Extraction Based on Anion-Functionalized Ionic Liquids for Selective Separation of Rare-Earth Ions  

SciTech Connect

In this study, solvation has been found to be a dominant mechanism in a comprehensive ionic liquid based extraction system for rare earth elements (REEs). Trioctylmethylammonium di(2-ethylhexyl)phosphate ([TOMA][DEHP]), an ionic-liquid extractant, was used in 1-alkyl-3-methylimidizolium bis[(trifluoromethyl)sulfonyl]imide ([Cnmim][NTf2], n = 4, 6, 8, 10) and 1-alkyl-3-methylimidizolium bis(perfluoroethanesulfonyl)imide ([Cnmim][BETI], n = 4, 6, 8, 10) for the separation of REEs. Surprisingly, a very similar extraction behavior was observed even as the carbon chain length on the ionic-liquid (IL) cation increased from butyl (C4) to hexyl (C6), to octyl (C8), to decyl (C10). This behavior is in sharp contrast to that exhibited by the conventional neutral extractants, whose extraction efficiencies are strongly dependent on the hydrophobicity of IL cations. Furthermore, the addition of IL cations ([Cnmim]+) or IL anions ([NTf2]- or [BETI]-) to the aqueous phase had little effect on the extraction behavior of the above extraction system, ruling out the strong involvement of the ion-exchange mechanism associated with traditional IL-based extraction systems. Results showed that the extractabilities and selectivities of REEs using [TOMA][DEHP] in [C10mim][NTf2]/[BETI] are several orders of magnitude better than those achieved using conventional organic solvent, diisopropylbenzene (DIPB). This study highlights the potential of developing a comprehensive IL-based extraction strategy for REEs separations.

Sun, Xiaoqi [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL

2013-01-01

211

Use of complexing reagents as additives to the eluent for optimization of separation selectivity in high-performance chelation ion chromatography  

Microsoft Academic Search

This paper details a study of the selectivity characteristics of high-performance chelation ion chromatography when separating a range of metal ions with a number of complexing eluents. It shows that exploitation of competitive metal complexation between ligands in the eluent and surface bonded chelating groups allows a wide range of control over the retention order and selectivity coefficients of groups

Phil Jones; Pavel N. Nesterenko

2008-01-01

212

Determination of ultratrace boron concentrations in uranium oxide by isotope dilution-thermal ionization mass spectrometry using a simplified separation procedure  

Microsoft Academic Search

Boron was determined at sub-ppm levels in uranium oxide by ID-TIMS. Following nitric acid dissolution, a solvent extraction\\u000a method was adapted for extraction of boron by 5% 2-ethylhexane-1,3-diol in chloroform followed by evaporation of the extractant\\u000a in presence of sodium carbonate and mannitol. This procedure allowed TIMS analysis of boron by monitoring the Na2BO2+ ions formed from the sodium borate

Radhika M. Rao; Ankush R. Parab; K. Sasi Bhushan; Suresh K. Aggarwal

2010-01-01

213

Novel microorganism for selective separation of coal from ash and pyrite. Seventh quarterly technical progress report, April 1, 1995--June 30, 1995  

SciTech Connect

The selective separation of pyrite and ash-forming minerals from coal can be accomplished by flotation, agglomeration and selective flocculation. The methods currently used for selective flocculation of coals include addition of natural or synthetic polymeric flocculants along with precise pH control. In some cases, these flocculants are nonselective or work imperfectly. It is known that many highly charged planktonic algae and bacteria will adhere to certain solid surfaces if the charge or hydrophobic interaction between the organism and the solids are favorable for adhesion. The resultant microorganism-mineral entities, if formed, can flocculate and can be separated. In addition, many living organisms produce extracellular biopolymers that can also cause flocculation. The microorganism, M. phlei, has the properties of being both highly charged and highly hydrophobic. The aim of the present investigation is to study the effectiveness of M. phlei and biopolymers derived from the organism for selective flocculation and separation of fine coal from pyrite and ash.

Misra, M.; Smith, R.W.; Raichur, A.M.

1996-12-31

214

Preserving Ultra-Pure Uranium233  

Microsoft Academic Search

Uranium-233 (²³³U) is a synthetic isotope of uranium formed under reactor conditions during neutron capture by natural thorium (²³²Th). At high purities, this synthetic isotope serves as a crucial reference material for accurately quantifying and characterizing uranium-bearing materials assays and isotopic distributions for domestic and international nuclear safeguards. Separated, high purity ²³³U is stored in vaults at Oak Ridge National

Alan M Krichinsky; Steven A. Goldberg; Ian D. Hutcheon

2011-01-01

215

Uranium droplet core nuclear rocket  

NASA Technical Reports Server (NTRS)

Uranium droplet nuclear rocket is conceptually designed to utilize the broad temperature range ofthe liquid phase of metallic uranium in droplet configuration which maximizes the energy transfer area per unit fuel volume. In a baseline system dissociated hydrogen at 100 bar is heated to 6000 K, providing 2000 second of Isp. Fission fragments and intense radian field enhance the dissociation of molecular hydrogen beyond the equilibrium thermodynamic level. Uranium droplets in the core are confined and separated by an axisymmetric vortex flow generated by high velocity tangential injection of hydrogen in the mid-core regions. Droplet uranium flow to the core is controlled and adjusted by a twin flow nozzle injection system.

Anghaie, Samim

1991-01-01

216

Rational development of a selection model for solvent gradients in single-step separation of ginsenosides from Panax ginseng using high-speed counter-current chromatography.  

PubMed

A new model of solvent gradients selection was rationally developed for the preparative separation of target compounds. The solvent gradients were selected based on a three-stage screening process where stationary phase retention was ensured by introducing a new parameter termed as the phase ratio. The phase ratio was calculated after mixing the upper phase of a solvent system with the lower phase of a different solvent system (1:1, v/v). The developed model was applied to the one-step separation of eight ginsenosides from Panax ginseng. Three gradients were selected on the basis of new model and eight ginsenosides, Rb(1), Rb(2), Rc, Rd, Re, Rg(1), Rf, and Rh(1), were efficiently separated by high-speed counter-current chromatography coupled with evaporative light scattering detector. The structures of all compounds were characterized by electrospray-ionization mass spectrometry and nuclear magnetic resonance spectroscopy. PMID:22740255

Shehzad, Omer; Khan, Salman; Ha, In Jin; Park, Youmie; Kim, Yeong Shik

2012-06-01

217

Effect of interwire separation on growth kinetics and properties of site-selective GaAs nanowires  

NASA Astrophysics Data System (ADS)

We report tuning of the growth kinetics, geometry, and properties of autocatalytic GaAs nanowires (NW) by precisely controlling their density on SiO2-mask patterned Si (111) substrates using selective area molecular beam epitaxy. Using patterned substrates with different mask opening size (40-120 nm) and pitch (0.25-3 ?m), we find that the NW geometry (length, diameter) is independent of the opening size, in contrast to non-catalytic GaAs NWs, whereas the NW geometry strongly depends on pitch, i.e., interwire separation and NW density. In particular, two distinct growth regimes are identified: a diffusion-limited regime for large pitches (low NW density) and a competitive growth regime for smaller pitches (high NW density), where axial and radial NW growth rates are reduced. The transition between these two regimes is significantly influenced by the growth conditions and shifts to smaller pitches with increasing As/Ga flux ratio. Ultimately, the pitch-dependent changes in growth kinetics lead to distinctly different photoluminescence properties, highlighting that mask template design is a very critical parameter for tuning intrinsic NW properties.

Rudolph, D.; Schweickert, L.; Morkötter, S.; Loitsch, B.; Hertenberger, S.; Becker, J.; Bichler, M.; Abstreiter, G.; Finley, J. J.; Koblmüller, G.

2014-07-01

218

Removal of uranium from aqueous HF solutions  

DOEpatents

This invention is a simple and effective method for removing uranium from aqueous HF solutions containing trace quantities of the same. The method comprises contacting the solution with particulate calcium fluoride to form uranium-bearing particulates, permitting the particulates to settle, and separting the solution from the settled particulates. The CaF.sub.2 is selected to have a nitrogen surface area in a selected range and is employed in an amount providing a calcium fluoride/uranium weight ratio in a selected range. As applied to dilute HF solutions containing 120 ppm uranium, the method removes at least 92% of the uranium, without introducing contaminants to the product solution.

Pulley, Howard (West Paducah, KY); Seltzer, Steven F. (Paducah, KY)

1980-01-01

219

Uranium and thorium occurrences in New Mexico: distribution, geology, production, and resources, with selected bibliography. Open-file report OF183. [Over 1300 uranium and thorium occurrences are described  

Microsoft Academic Search

Over 1300 uranium and thorium occurrences are found in over 100 formational units in all but two counties, in all 1- by 2-degree topographic quadrangles, and in all four geographic provinces in New Mexico. Uranium production in New Mexico has surpassed yearly production from all other states since 1956. Over 200 mines in 18 counties in New Mexico have produced

McLemore

1983-01-01

220

Seperation of neptunium from irradiated uranium targets  

Microsoft Academic Search

A new chemical method based in two separation steps was developed to isolate235Np from uranium targets irradiated with charged particles. Neptunium and plutonium are separated from uranium and most of the fission products by ion exchange. Then, neptunium is isolated from plutonium and remaining contaminants by extraction chromatography with tributyl phosphate in hydrochloric acid solution. High decontamination was achieved.

L. F. Bellido; V. J. Robinson; H. E. Sims

1993-01-01

221

Chelating polymers and related supports for separation and preconcentration of trace metals.  

PubMed

This review is concerned mainly with the applications of chelating polymeric resins for the separation and concentration of trace metals from oceans, rivers, streams and other natural systems. Commercially available resins, specially prepared polymers and a selection of other sorbents are described and their uses outlined. Special emphasis is placed on the preconcentration of uranium from sea-water. PMID:18964972

Kantipuly, C; Katragadda, S; Chow, A; Gesser, H D

1990-05-01

222

The selection of suitable columns for a reversed-phase liquid chromatographic separation of beta-lactam antibiotics and related substances via chromatographic column parameters.  

PubMed

The selection of RP-LC columns suitable for a particular analysis in official compendia is difficult as only a general description of the stationary phase in the description of a LC method is given. General methods to characterize RP-LC columns often assume that each of the column parameters is equally important. This can cause the user to select columns inappropriate for particular analyses. This paper focuses on the relationship between the critical peak pairs and the column parameters (H, S, A, B, and C) in the Snyder/Dolan column characterization methodology to find the key parameters influencing real separations. Some varieties of ?-lactam antibiotics and their related compounds were used as test compounds. We found column parameter A to be the most important factor affecting their separation. Parameters B and C also played an important role in some separation processes. This indicated that the hydrogen bonding of column and solute can directly affect the separation of ?-lactam antibiotics. Choosing columns for which column parameter A is near 0.1 can facilitate the ideal separations of impurities from ?-lactam antibiotics. The most suitable column for any common pharmaceutical analysis could be selected easily if the key column parameters would be given in the description of the chromatographic method. For these reasons, key column parameters should be listed in the monographs of official compendia. PMID:24304649

Zhang, Wei-qing; Hu, Qiu-xin; Zhang, Xia; Li, Ya-ping; Wang, Ming-juan; Hu, Chang-qin

2014-01-01

223

ANTHEM BLUE CROSS AND BLUE SHIELD You may select from two separate dental care plans to meet your individual needs. Premium cost  

E-print Network

- 34 - ANTHEM BLUE CROSS AND BLUE SHIELD You may select from two separate dental care plans to meet two choices are: Anthem Blue Dental PPO Plus Anthem Blue Dental PPO NOTE: Children are eligible in retirement. PERA retirement benefits are based on your highest three years of earnings. Anthem Blue Dental

224

Differential geochemical mobility of uranium, thorium, and potassium used as geologic environment indicators and explorations tools  

Microsoft Academic Search

Uranium and potassium are easily leached from tuffaceous rocks, although thorium is not. Transport efficiency is higher for potassium than uranium. Uranium is immobilized by reduction or complexing. Potassium tends to be more thoroughly flushed, although it may be retained on clays and stabilized during diagenesis. Uranium and potassium tend to be separated during uranium precipitation. Organic-rich shales and uraniferous

Philip C. Goodell

1986-01-01

225

Neutron-Rich Isotope Production Using a Uranium Carbide Carbon Nanotubes SPES Target Prototype  

SciTech Connect

The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community.

Corradetti, Stefano [ORNL; Biasetto, Lisa [INFN, Laboratori Nazionali di Legnaro, Italy; Manzolaro, Mattia [INFN, Laboratori Nazionali di Legnaro, Italy; Scarpa, Daniele [ORNL; Carturan, S. [INFN, Laboratori Nazionali di Legnaro, Italy; Andrighetto, Alberto [INFN, Laboratori Nazionali di Legnaro, Italy; Prete, Gianfranco [ORNL; Vasquez, Jose L [ORNL; Zanonato, P. [Dipartimento di Scienze Chimiche, Padova, Italy; Colombo, P. [Dipartimento di Ingegneria Meccanica, Padova, Italy; Jost, Carola [University of Tennessee, Knoxville (UTK); Stracener, Daniel W [ORNL

2013-01-01

226

Neutron-rich isotope production using a uranium carbide - carbon nanotubes SPES target prototype  

NASA Astrophysics Data System (ADS)

The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community.

Corradetti, S.; Biasetto, L.; Manzolaro, M.; Scarpa, D.; Carturan, S.; Andrighetto, A.; Prete, G.; Vasquez, J.; Zanonato, P.; Colombo, P.; Jost, C. U.; Stracener, D. W.

2013-05-01

227

Battery separators.  

PubMed

The ideal battery separator would be infinitesimally thin, offer no resistance to ionic transport in electrolytes, provide infinite resistance to electronic conductivity for isolation of electrodes, be highly tortuous to prevent dendritic growths, and be inert to chemical reactions. Unfortunately, in the real world the ideal case does not exist. Real world separators are electronically insulating membranes whose ionic resistivity is brought to the desired range by manipulating the membranes thickness and porosity. It is clear that no single separator satisfies all the needs of battery designers, and compromises have to be made. It is ultimately the application that decides which separator is most suitable. We hope that this paper will be a useful tool and will help the battery manufacturers in selecting the most appropriate separators for their batteries and respective applications. The information provided is purely technical and does not include other very important parameters, such as cost of production, availability, and long-term stability. There has been a continued demand for thinner battery separators to increase battery power and capacity. This has been especially true for lithiumion batteries used in portable electronics. However, it is very important to ensure the continued safety of batteries, and this is where the role of the separator is greatest. Thus, it is essential to optimize all the components of battery to improve the performance while maintaining the safety of these cells. Separator manufacturers should work along with the battery manufacturers to create the next generation of batteries with increased reliability and performance, but always keeping safety in mind. This paper has attempted to present a comprehensive review of literature on separators used in various batteries. It is evident that a wide variety of separators are available and that they are critical components in batteries. In many cases, the separator is one of the major factors limiting the life and/or performance of batteries. Consequently, development of new improved separators would be very beneficial for the advanced high capacity batteries. PMID:15669158

Arora, Pankaj; Zhang, Zhengming John

2004-10-01

228

Uranium and thorium occurrences in New Mexico: distribution, geology, production, and resources, with selected bibliography. Open-file report OF-183. [Over 1300 uranium and thorium occurrences are described  

SciTech Connect

Over 1300 uranium and thorium occurrences are found in over 100 formational units in all but two counties, in all 1- by 2-degree topographic quadrangles, and in all four geographic provinces in New Mexico. Uranium production in New Mexico has surpassed yearly production from all other states since 1956. Over 200 mines in 18 counties in New Mexico have produced 163,010 tons (147,880 metric tons) of U/sub 3/O/sub 8/ from 1948 to 1982, 40% of the total uranium production in the United States. More than 99% of this production has come from sedimentary rocks in the San Juan Basin area in northwestern New Mexico; 96% has come from the Morrison Formation alone. All of the uranium reserves and the majority of the potential uranium resources in New Mexico are in the Grants uranium district. About 112,500 tons (102,058 metric tons) of $30 per pound of U/sub 3/O/sub 8/ reserves are in the San Juan Basin, about 55% of the total $30 reserves in the United States. Thorium reserves and resources in New Mexico have not been adequately evaluated and are unknown. Over 1300 uranium and thorium occurrences are described in this report, about 400 of these have been examined in the field by the author. The occurrence descriptions include information on location, commodities, production, development, geology, and classification. Over 1000 citations are included in the bibliography and referenced in the occurrence descriptions. Production statistics for uranium mines that operated from 1948 to 1970 are also included. Mines that operated after 1970 are classified into production categories. 43 figures, 9 tables.

McLemore, V.T.

1983-09-01

229

APPLICATION OF CYCLODEXTRIN-MODIFIED MICELLAR ELECTRONKINETIC CHROMATOGRAPHY TO THE SEPARATIONS OF SELECTED NEUTRAL PESTICIDES AND THEIR ENANTIOMERS  

EPA Science Inventory

The environmental chemistry of chiral pesticides is receiving increased attention - enantiomeric ratios are being measured and enantioselective degradation processes are being reported. The requisite analysis involves separation of the various enantiomers. Mixtures of three class...

230

Uranium determination by 133 Xe in mineral separates from igneous rocks comparative study with fission track and thermal release characters of 133 Xe  

Microsoft Academic Search

Samples of an andesite (Asama-yama, Japan) and a basalt (Kilauea, Hawaii) were finely fractioned by density and the U distributions\\u000a among the separates were determined by homogenized fission track method. Groundmass was found to be enriched with U; one half\\u000a of the andesite U and almost all of the basalt U are accounted for by the groundmass U. Cerium and

K. Sakamoto; Y. Hamajima; S. Yamaguchi; T. Takashima; K. Itoh

1980-01-01

231

Synthesis of highly methanol selective membranes for separation of methyl tertiary butyl ether (MTBE)–methanol mixtures by pervaporation  

Microsoft Academic Search

Methyl tertiary butyl ether (MTBE) is now being extensively used as a lead-free octane enhancer for green fuel. Pervaporative separation process is used for separation of methanol–MTBE mixtures encountered during manufacturing of MTBE. Three different copolymers of acrylamide with increasing amount of 2-hydroxyethyl methacrylate (HEMA), i.e. PAMHEMA-1, -2 and -3 were synthesized and the cross-linked (gelled) copolymer membranes made from

S. Ray

2006-01-01

232

Flash chromatography on cartridges for the separation of plant extracts: rules for the selection of chromatographic conditions and comparison with medium pressure liquid chromatography.  

PubMed

Empirical rules for the selection of chromatographic conditions on flash chromatography cartridges were developed, with an emphasis on gradient mode. These rules were then tested with separation of extracts from important medicinal plants including Curcuma xanthorrhiza, Piper nigrum and Salvia milthiorrhiza. Sepacore® cartridges enabled a good separation of compounds with a broad range of polarity, as typically found in plant extracts. The chromatographic resolution remained, however, lower than that achieved on classical columns packed with material of smaller particle size. For poorly soluble extracts, solid introduction gave better results than liquid injection. PMID:20804823

Weber, Petra; Hamburger, Matthias; Schafroth, Nina; Potterat, Olivier

2011-03-01

233

Toward understanding the influence of ethylbenzene in p-xylene selectivity of the porous titanium amino terephthalate MIL-125(Ti): adsorption equilibrium and separation of xylene isomers.  

PubMed

The potential of the porous crystalline titanium dicarboxylate MIL-125(Ti) in powder form was studied for the separation in liquid phase of xylene isomers and ethylbenzene (MIL stands for Materials from Institut Lavoisier). We report here a detailed experimental study consisting of binary and multi-component adsorption equilibrium of xylene isomers in MIL-125(Ti) powder at low (?0.8 M) and bulk (?0.8 M) concentrations. A series of multi-component breakthrough experiments was first performed using n-heptane as the eluent at 313 K, and the obtained selectivities were compared, followed by binary breakthrough experiments to determine the adsorption isotherms at 313 K, using n-heptane as the eluent. MIL-125(Ti) is a para-selective material suitable at low concentrations to separate p-xylene from the other xylene isomers. Pulse experiments indicate a separation factor of 1.3 for p-xylene over o-xylene and m-xylene, while breakthrough experiments using a diluted ternary mixture lead to selectivity values of 1.5 and 1.6 for p-xylene over m-xylene and o-xylene, respectively. Introduction of ethylbenzene in the mixture results however in a decrease of the selectivity. PMID:22260425

Moreira, Mariana A; Santos, João C; Ferreira, Alexandre F P; Loureiro, José M; Ragon, Florence; Horcajada, Patricia; Yot, Pascal G; Serre, Christian; Rodrigues, Alírio E

2012-02-21

234

Depleted Uranium  

MedlinePLUS

... Toll Free Numbers VA » Health Care » Public Health » Military Exposures » Depleted Uranium Public Health Public Health Public Health Home Military Exposures Military Exposures Home 4 Ways to Find ...

235

Study of leachable uranium, thorium, and radium isotopes and associated radon emanations from selected samples of fly ash  

Microsoft Academic Search

The leachability of U, Th, and Ra isotopes from selected samples of fly ash generated in coal-fired power plants was measured by the Column method, the proposed ASTM Batch method, and the Long-term Batch method. The activities of Ra-226, Ra-228, U-234, U-235, U-238, and Th-232 in the fly ash used in the leaching tests were determined to be 1.96, 1.63,

1982-01-01

236

Pregnancy outcome in mares following insemination deep in the uterine horn with low numbers of sperm selected by glass wool/Sephadex filtration, Percoll separation or absolute number.  

PubMed

Mares were inseminated deep in the uterine horn with 25 million sperm selected by glass wool/Sephadex (GWS) filtration, Percoll separation (PS) or absolute number (AN). Deep-horn insemination using a low-volume, smooth tipped, flexible pipette/catheter delivery system allowed more efficient use of stallion sperm and reduced post-breeding uterine reaction in mares. Mares were pregnant in 15/30, 13/30 and 10/30 cycles for GWS, PS and AN selection methods, respectively. Sperm selection method did not effect pregnancy outcome (P=0.422). However, sperm selected for deep-horn insemination by filtration through a glass wool/Sephadex column tended to improve fertility over simply using an absolute number of sperm (P=0.105). PMID:12853183

Nie, Gary J; Johnson, Kristina E; Wenzel, James G W

2003-11-20

237

INFORMATION: Management Alert on Environmental Management's Select Strategy for Disposition of Savannah River Site Depleted Uranium Oxides  

SciTech Connect

The Administration and the Congress, through policy statements and passage of the American Recovery and Reinvestment Act of 2009 (Recovery Act), have signaled that they hope that proactive actions by agency Inspectors General will help ensure that Federal Recovery Act activities are transparent, effective and efficient. In that context, the purpose of this management alert is to share with you concerns that have been raised to the Office of Inspector General regarding the planned disposition of the Savannah River Site's (SRS) inventory of Depleted Uranium (DU) oxides. This inventory, generated as a by-product of the nuclear weapons production process and amounting to approximately 15,600 drums of DU oxides, has been stored at SRS for decades. A Department source we deem reliable and credible recently came to the Office of Inspector General expressing concern that imminent actions are planned that may not provide for the most cost effective disposition of these materials. During April 2009, the Department chose to use funds provided under the Recovery Act to accelerate final disposition of the SRS inventory of DU oxides. After coordination with State of Utah regulators, elected officials and the U.S. Nuclear Regulatory Commission, the Department initiated a campaign to ship the material to a facility operated by EnergySolutions in Clive, Utah. Although one shipment of a portion of the material has already been sent to the EnergySolutions facility, the majority of the product remains at SRS. As had been planned, both for the shipment already made and those planned in the near term, the EnergySolutions facility was to have been the final disposal location for the material. Recently, a member of Congress and various Utah State officials raised questions regarding the radioactive and other constituents present in the DU oxides to be disposed of at the Clive, Utah, facility. These concerns revolved around the characterization of the material and its acceptability under existing licensing criteria. As a consequence, the Governor of Utah met with Department officials to voice concerns regarding further shipments of the material and to seek return of the initial shipment of DU oxides to SRS. Utah's objections and the Department's agreement to accede to the State's demands effectively prohibit the transfer of the remaining material from South Carolina to Utah. In response, the Department evaluated its options and issued a draft decision paper on March 1, 2010, which outlined an alternative for temporary storage until the final disposition issue could be resolved. Under the terms of the proposed option, the remaining shipments from SRS are to be sent on an interim basis to a facility owned by Waste Control Specialists (WCS) in Andrews, Texas. Clearly, this choice carries with it a number of significant logistical burdens, including substantial additional costs for, among several items, repackaging at SRS, transportation to Texas, storage at the interim site, and, repackaging and transportation to the yet-to-be-determined final disposition point. The Department source expressed the concern that the proposal to store the material on an interim basis in Texas was inefficient and unnecessary, asserting: (1) that the materials could remain at SRS until a final disposition path is identified, and that this could be done safely, securely and cost effectively; and, (2) that the nature of the material was not subject to existing compliance agreements with the State of South Carolina, suggesting the viability of keeping the material in storage at SRS until a permanent disposal site is definitively established. We noted that, while the Department's decision paper referred to 'numerous project and programmatic factors that make it impractical to retain the remaining inventory at Savannah River,' it did not outline the specific issues involved nor did it provide any substantive economic or environmental analysis supporting the need for the planned interim storage action. The only apparent driver in this case was a Recovery Act-related goal esta

None

2010-04-01

238

Highly Selective Adsorption and Separation of Aniline/Phenol from Aqueous Solutions by Microporous MIL-53(Al): A Combined Experimental and Computational Study.  

PubMed

Experimental measurements have been combined with molecular simulations to investigate the adsorption and separation of aniline/phenol mixtures from aqueous solutions by the aluminum terephthalate MIL-53. The results show that the framework flexibility of this material plays a crucial role in the adsorption process and thus can greatly enhance the separation of the aniline/phenol mixture from their solutions. Compared with the conventional adsorbents, MIL-53(Al) shows the best performance for such systems of interest, from the points of view of both the adsorption capacities and the selectivities for aniline. The findings obtained in this work may facilitate more investigations in connection with the application of flexible nanoporous materials for the separation of organic compounds from liquid-phase environments. PMID:25251810

Xiao, Yuanlong; Han, Tongtong; Xiao, Gang; Ying, Yunpan; Huang, Hongliang; Yang, Qingyuan; Liu, Dahuan; Zhong, Chongli

2014-10-21

239

Enhanced Control of PWR Primary Coolant Water Chemistry Using Selective Separation Systems for Recovery and Recycle of Enriched Boric Acid  

SciTech Connect

The objective of this project is to develop systems that will allow for increased nuclear energy production through the use of enriched fuels. The developed systems will allow for the efficient and selective recover of selected isotopes that are additives to power water reactors' primary coolant chemistry for suppression of corrosion attack on reactor materials.

Ken Czerwinski; Charels Yeamans; Don Olander; Kenneth Raymond; Norman Schroeder; Thomas Robison; Bryan Carlson; Barbara Smit; Pat Robinson

2006-02-28

240

Separations of corticosteroids using electrochemically modulated liquid chromatography: Selectivity enhancements at a porous graphitic carbon stationary phase  

SciTech Connect

Electrochemically modulated liquid chromatography has been applied to the separation of a mixture of structurally similar corticosteroids (i.e., prednisone, prednisolone, cortisone, and hydrocortisone) using a porous graphitic carbon stationary phase. Changes in the voltage applied to the column markedly affected the efficiency as well as the elution order of the separation, with the mixture fully resolved at large negative values of applied potential. Mechanistic aspects in terms of the influence of changes in the applied voltage on the extent of the interactions between these analytes and the stationary phase are briefly discussed. 19 refs., 2 figs.

Ting, E.Y.; Porter, M.D. [Ames Lab., IA (United States)] [Ames Lab., IA (United States); [Iowa State Univ., Ames, IA (United States)

1997-02-15

241

Selective Separation of Nickel (II) and Cobalt (II) from Waste Water by Using Continuous Cross-Flow Micellar Enhanced Ultrafiltration with Addition of Chelating Agent  

Microsoft Academic Search

The performance of continuous cross-flow micellar enhanced ultrafiltration (MEUF) is evaluated for the selective separation of nickel (Ni) and cobalt (Co) from the aqueous stream using anionic surfactant sodiumdodecyl sulfate (SDS) and mixture of anionic and nonionic surfactant (SDS+TritonX-100) with addition of iminodiacetic acid (IDA) as a chelating agent. Operating parameters like operating time (upto 100 min), cross flow rate (100-175 ml\\/min.),

P. N. Patil; K. V. Marathe

2012-01-01

242

Micro-column solid phase extraction to determine uranium and thorium in environmental samples.  

PubMed

Extraction chromatographic separation techniques based on U/TEVA and TEVA resins were utilized to separate uranium and thorium isotopes in complex matrices from environmental samples. This approach has the advantages of ease of quantitative analysis, small sample size, an absence of mixed waste solvents, complete separation of U/Th isotopes, acceptable chemical yields and good energy resolution in the alpha spectrum. The procedure for analyzing alpha-emitting isotopes of uranium and thorium in geothermal water from Peito, Taiwan, is illustrated in detail. It involves sample pre-concentration, filtration and separation by highly selective extraction chromatographic resins, followed by electroplating and alpha-spectroscopy. The analytical results show a chemical recovery exceeding 55% for U and 65% for Th, respectively, under optimized conditions. The efficient and cost-effective use of recyclable columns makes the analytical methods simple, accurate, rapid, reliable and robust. PMID:18430577

Tsai, Tsuey-Lin; Lin, Chun-Chih; Chu, Tieh-Chi

2008-08-01

243

Selectivity of bis-triazinyl bipyridine ligands for americium(III) in Am/Eu separation by solvent extraction. Part 1. Quantum mechanical study on the structures of BTBP complexes and on the energy of the separation.  

PubMed

Theoretical studies were carried out on two pairs of americium and europium complexes formed by tetra-N-dentate lipophilic BTBP ligands, neutral [ML(NO(3))(3)] and cationic [ML(2)](3+) where M = Am(III) or Eu(III), and L = 6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (C2-BTBP). Molecular structures of the complexes have been optimized at the B3LYP/6-31G(d) level and total energies of the complexes in various media were estimated using single point calculations performed at the B3LYP/6-311G(d,p) and MP2/6-311G(d,p) levels of theory. In the calculations americium and europium ions were treated using pseudo-relativistic Stuttgart-Dresden effective core potentials and the accompanying basis sets. Selectivity in solvent extraction separation of two metal ions is a co-operative function of contributions from all extractable metal complexes, which depend on physico-chemical properties of each individual complex and on its relative amount in the system. Semi-quantitative analysis of BTBP selectivity in the Am/Eu separation process, based on the contributions from the two pairs of Am(III) and Eu(III) complexes, has been carried out. To calculate the energy of Am/Eu separation, a model of the extraction process was used, consisting of complex formation in water and transfer of the formed complex to the organic phase. Under the assumptions discussed in the paper, this simple two-step model results in reliable values of the calculated differences in the energy changes for each pair of the Am/Eu complexes in both steps of the process. The greater thermodynamic stability (in water) of the Am-BTBP complexes, as compared with the analogous Eu species, caused by greater covalency of the Am-N than Eu-N bonds, is most likely the main reason for BTBP selectivity in the separation of the two metal ions. The other potential reason, i.e. differences in lipophilic properties of the analogous complexes of Am and Eu, is less important with regard to this selectivity. PMID:23104258

Narbutt, Jerzy; Oziminski, Wojciech P

2012-12-21

244

Liquid chromatography on silica using mobile phases containing tetraalkylammonium hydroxides. I. General separation selectivity and behavior of polar compounds typically in fuels  

SciTech Connect

The known selectivity of base-modified silicas for acidic solutes led to development of the in-situ tetraalkylammonium hydroxide (TAAH)-modified silica HPLC systems described here. These systems are generated by adding small concentrations of TAAH to normal phase eluents pumped through conventional silica columns. The in-situ approach has the following advantages: the type and concentration of TAAH can be varied to control separation behavior and selectivity; greater column-to-column consistency and separation reproducibility is achieved; commercially available columns and packings are used; and the TAAH in the mobile phase also serves as an electrolyte for electrochemical detection of solutes, if desired. Retention of 180 solutes spanning several classes of compounds is measured in four different systems; the applicability of this approach to separation of acid concentrates from fuels as well as its compatibility with electrochemical detectors is demonstrated; and in addition, general chromatographic parameters such as the effect of the mobile phase composition on retention and selectivity are discussed. 23 refs., 5 figs., 6 tabs.

Green, J.B.

1985-06-01

245

Bioassay measurements for uranium using Sputter Initiated Resonance Ionization Spectroscopy  

SciTech Connect

It was determined earlier in a feasibility study that Sputter Initiated Resonance Ionization Spectroscopy (SIRIS) would be feasible as an ultrasensitive analytical method for the detection of uranium, plutonium, and thorium in urine and other bioassay samples. SIRIS is a method which uses sputtering to atomize a sample, tunable dye lasers to selectively ionize the element of interest, and a mass spectrometer to detect the separated isotopes of the selected element. We report here demonstration measurements for the analysis of uranium in simple aqueous solution and in synthetic urine to a detection limit of 1 g/l. Sample preparation procedures are discussed. The technique of isotope dilution was used for calibration. The results of the measurements are reported and discussed. Steps to lower the detection limit to 0.05 g/l are reported. Cost estimates for routine analyses are reviewed. 4 refs., 2 figs., 2 tabs.

Parks, J.E.; Taylor, E.H.; Beekman, D.W.; Spaar, M.T.

1986-01-01

246

A new MOF-5 homologue for selective separation of methane from C2 hydrocarbons at room temperature  

NASA Astrophysics Data System (ADS)

A new MOF-5 homologue compound UTSA-10 has been obtained under solvothermal conditions from a mixture of Zn(NO3)2?6H2O and commercially available linker, 2-methylfumaric acid, in N,N-dimethylformamide. The moderate surface area and suitable pore sizes enable the activated UTSA-10a to separate methane from C2 hydrocarbons at room temperature.

He, Yabing; Song, Chengling; Ling, Yajing; Wu, Chuande; Krishna, Rajamani; Chen, Banglin

2014-12-01

247

Corrosion-resistant uranium  

DOEpatents

The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

Hovis, Jr., Victor M. (Kingston, TN); Pullen, William C. (Knoxville, TN); Kollie, Thomas G. (Oak Ridge, TN); Bell, Richard T. (Knoxville, TN)

1983-01-01

248

Uranium reduction.  

PubMed

The dramatic decrease in solubility accompanying the reduction of U(VI) to U(IV), producing the insoluble mineral uraninite, has been viewed as a potential mechanism for sequestration of environmental uranium contamination. In the past 15 years, it has been firmly established that a variety of bacteria exhibit this reductive capacity. To obtain an understanding of the microbial metal metabolism, to develop a practical approach for the acceleration of in situ bioreduction, and to predict the long-term fate of environmental uranium, several aspects of the microbial process have been experimentally explored. This review briefly addresses the research to identify specific uranium reductases and their cellular location, competition between uranium and other electron acceptors, attempts to stimulate in situ reduction, and mechanisms of reoxidation of reduced uranium minerals. PMID:16704344

Wall, Judy D; Krumholz, Lee R

2006-01-01

249

Uranium-Lead Zircon Ages and Sr, Nd, and Pb Isotope Geochemistry of Selected Plutonic Rocks from Western Idaho  

USGS Publications Warehouse

Across the Salmon River suture in western Idaho, where allochthonous Permian to Cretaceous oceanic rocks are juxtaposed against Proterozoic North American rocks, a wide variety of plutonic rocks are exposed. Available data indicate much variation in composition, source, and structural state of these plutons. The plutonic rocks were long described as the western border zone of the Cretaceous Idaho batholith but limited pre-existing age data indicate more complicated origins. Because the affinity and age of the plutonic rocks cannot be reliably determined from field relations, TIMS U-Pb dating in conjunction with Sr, Nd, and Pb isotopic studies of selected plutons across the suture in western Idaho were undertaken. The data indicate three general groups of plutons including (1) those that intruded the island arc terranes during the Triassic and Jurassic, those that intruded near the western edge of oceanic rocks along the suture in the Early Cretaceous, and the plutons of the Idaho batholith that intruded Proterozoic North American rocks in the Late Cretaceous. Plutons that intruded Proterozoic North American rocks commonly include xenocrystic zircons and in several cases, ages could not be determined. The least radiogenic Sr and most radiogenic Nd are found among the Blue Mountains superterrane island arc samples. Suture-zone plutons have isotopic characteristics that span the range between Idaho batholith and island arc samples but mostly follow island arc signatures. Plutons of the Idaho batholith have the most radiogenic initial Pb and Sr ratios and the least radiogenic Nd of the samples analyzed.

Unruh, Daniel M.; Lund, Karen; Kuntz, Mel A.; Snee, Lawrence W.

2008-01-01

250

Diffusive gradient in thin FILMS (DGT) compared with soil solution and labile uranium fraction for predicting uranium bioavailability to ryegrass.  

PubMed

The usefulness of uranium concentration in soil solution or recovered by selective extraction as unequivocal bioavailability indices for uranium uptake by plants is still unclear. The aim of the present study was to test if the uranium concentration measured by the diffusive gradient in thin films (DGT) technique is a relevant substitute for plant uranium availability in comparison to uranium concentration in the soil solution or uranium recovered by ammonium acetate. Ryegrass (Lolium perenne L. var. Melvina) is grown in greenhouse on a range of uranium spiked soils. The DGT-recovered uranium concentration (C(DGT)) was correlated with uranium concentration in the soil solution or with uranium recovered by ammonium acetate extraction. Plant uptake was better predicted by the summed soil solution concentrations of UO(2)(2+), uranyl carbonate complexes and UO(2)PO(4)(-). The DGT technique did not provide significant advantages over conventional methods to predict uranium uptake by plants. PMID:19822385

Duquène, L; Vandenhove, H; Tack, F; Van Hees, M; Wannijn, J

2010-02-01

251

Uranium Transport Modeling  

SciTech Connect

Uranium contamination is prevalent at many of the U.S. DOE facilities and at several civilian sites that have supported the nuclear fuel cycle. The potential off-site mobility of uranium depends on the partitioning of uranium between aqueous and solid (soil and sediment) phases. Hexavalent U (as uranyl, UO{sub 2}{sup 2+}) is relatively mobile, forming strong complexes with ubiquitous carbonate ion which renders it appreciably soluble even under mild reducing conditions. In the presence of carbonate, partition of uranyl to ferri-hydrate and select other mineral phases is usually maximum in the near-neutral pH range {approx} 5-8. The surface complexation reaction of uranyl with iron-containing minerals has been used as one means to model subsurface migration, used in conjunction with information on the site water chemistry and hydrology. Partitioning of uranium is often studied by short-term batch 'equilibrium' or long-term soil column testing ; MCLinc has performed both of these methodologies, with selection of method depending upon the requirements of the client or regulatory authority. Speciation of uranium in soil may be determined directly by instrumental techniques (e.g., x-ray photoelectron spectroscopy, XPS; x-ray diffraction, XRD; etc.) or by inference drawn from operational estimates. Often, the technique of choice for evaluating low-level radionuclide partitioning in soils and sediments is the sequential extraction approach. This methodology applies operationally-defined chemical treatments to selectively dissolve specific classes of macro-scale soil or sediment components. These methods recognize that total soil metal inventory is of limited use in understanding bioavailability or metal mobility, and that it is useful to estimate the amount of metal present in different solid-phase forms. Despite some drawbacks, the sequential extraction method can provide a valuable tool to distinguish among trace element fractions of different solubility related to mineral phases. Four case studies are presented: Water and Soil Characterization, Subsurface Stabilization of Uranium and other Toxic Metals, Reductive Precipitation (in situ bioremediation) of Uranium, and Physical Transport of Particle-bound Uranium by Erosion.

Bostick, William D. [Materials and Chemistry Laboratory, Inc. (MCLinc), East Tennessee Technology Park, Building K-1006, 2010 Highway 58, Suite 1000, Oak Ridge, Tennessee 37830-1702 (United States)

2008-01-15

252

Transuranic separation using organophophorus extractants adsorbed onto superparamagnetic carriers.  

SciTech Connect

Polymeric coated ferromagnetic carriers with an absorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted by tributyl phosphate (TBP) are being evaluated for application in the separation and the recovery of low concentrations of americium, plutonium, and uranium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles and the complexed particles can be recovered from the solution using a magnet. Physical and chemical characterization of the extractant-absorbed particles were performed by gamma and liquid scintillation counting, scanning electron microscopic (SEM) micrograph, and other physical measurements. Plutonium, americium, and uranium separations have been performed at various HNO{sub 3} and HCl concentrations. Parameters were studied to determine the limitations and capacity of the process. The status of the chemistry and application of the process to Department of Energy (DOE) remediation efforts for actinide decontamination are discussed.

Nunez, L.

1998-10-07

253

A highly permeable and selective amino-functionalized MOF CAU-1 membrane for CO2-N2 separation.  

PubMed

A thin tubular CAU-1 membrane of 2-3 ?m exhibiting a high CO2 permeance of up to 1.34 × 10(-6) mol m(-2) s(-1) Pa(-1) and a CO2-N2 selectivity of 17.4-22.8 for CO2-N2 mixtures was achieved, demonstrating for the first time that amino-functionalized MOF membranes can provide high CO2-N2 selectivity and possess the potential for CO2 capture from flue gas. PMID:24573544

Yin, Huimin; Wang, Jinqu; Xie, Zhong; Yang, Jianhua; Bai, Ju; Lu, Jinming; Zhang, Yan; Yin, Dehong; Lin, Jerry Y S

2014-04-11

254

A new tetrazolate zeolite-like framework for highly selective CO2/CH4 and CO2/N2 separation.  

PubMed

A new tetrazolate zeolite-like framework with a diamond topology, UTSA-49, was synthesized. UTSA-49 shows high selectivity for CO2/CH4 and CO2/N2 indicating a synergistic effect of the suitable pore size/shape and functional groups. PMID:25168357

Xiong, Shunshun; Gong, Youjin; Wang, Hongxia; Wang, Hailong; Liu, Qiang; Gu, Mei; Wang, Xiaolin; Chen, Banglin; Wang, Zhiyong

2014-10-18

255

Uranium chloride extraction of transuranium elements from LWR fuel  

SciTech Connect

A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products is disclosed. The oxide fuel is reduced with Ca metal in the presence of Ca chloride and a U-Fe alloy which is liquid at about 800{degrees}C to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein. The U-Fe alloy having dissolved therein reduced metals from the spent nuclear fuel is contacted with a mixture of one or more alkali metal or alkaline earth metal halides selected from the class consisting of alkali metal or alkaline earth metal and Fe or U halide or a combination thereof to transfer transuranium actinide metals and rare earth metals to the halide salt leaving the uranium and some noble metal fission products in the U-Fe alloy and thereafter separating the halide salt and the transuranium metals dissolved therein from the U-Fe alloy and the metals dissolved therein.

Miller, W.E.; Ackerman, J.P.; Battles, J.E.; Johnson, T.R.; Pierce, R.D.

1991-12-31

256

Uranium chloride extraction of transuranium elements from LWR fuel  

DOEpatents

A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products is disclosed. The oxide fuel is reduced with Ca metal in the presence of Ca chloride and a U-Fe alloy which is liquid at about 800 C to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein. The U-Fe alloy having dissolved therein reduced metals from the spent nuclear fuel is contacted with a mixture of one or more alkali metal or alkaline earth metal halides selected from the class consisting of alkali metal or alkaline earth metal and Fe or U halide or a combination thereof to transfer transuranium actinide metals and rare earth metals to the halide salt leaving the uranium and some noble metal fission products in the U-Fe alloy and thereafter separating the halide salt and the transuranium metals dissolved therein from the U-Fe alloy and the metals dissolved therein. 1 figure.

Miller, W.E.; Ackerman, J.P.; Battles, J.E.; Johnson, T.R.; Pierce, R.D.

1992-08-25

257

Selective CO[sub 2] separation from CO[sub 2]-N[sub 2] mixtures by immobilized carbonate-glycerol membranes  

SciTech Connect

Acid gases present in numerous industrial waste gas streams have caused increasing global environmental concerns. To alleviate the pollution problems, acid gases in such streams need to be removed. The increased demand for acid gas treating and the cost of purification by conventional processes suggest a need for energy-efficient and selective gas-treating technology. Recent application of membrane separation of CO[sub 2] has been attracting attention due to its inherent simplicity, ease of control, compact modular nature, and great potential for lower cost and energy efficiency compared to traditional separation methods. These attractive features have stimulated significant research in gas separation using polymeric as well as liquid membranes. Separation of carbon dioxide from a humid mixture of CO[sub 2]-N[sub 2] through membranes containing immobilized solutions of Na[sub 2]CO[sub 3]-glycerol in porous and hydrophilic poly(vinylidene fluoride) (PVDF) substrate was experimentally studied. The effects of Na[sub 2]CO[sub 3] concentration, CO[sub 2] partial pressure, and feed stream relative humidity (RH) were investigated.

Chen, H.; Kovvali, A.S.; Majumdar, S.; Sirkar, K.K. (New Jersey Inst. of Tech., Newark, NJ (United States))

1999-09-01

258

Selective CO{sub 2} separation from CO{sub 2}-N{sub 2} mixtures by immobilized carbonate-glycerol membranes  

SciTech Connect

Acid gases present in numerous industrial waste gas streams have caused increasing global environmental concerns. To alleviate the pollution problems, acid gases in such streams need to be removed. The increased demand for acid gas treating and the cost of purification by conventional processes suggest a need for energy-efficient and selective gas-treating technology. Recent application of membrane separation of CO{sub 2} has been attracting attention due to its inherent simplicity, ease of control, compact modular nature, and great potential for lower cost and energy efficiency compared to traditional separation methods. These attractive features have stimulated significant research in gas separation using polymeric as well as liquid membranes. Separation of carbon dioxide from a humid mixture of CO{sub 2}-N{sub 2} through membranes containing immobilized solutions of Na{sub 2}CO{sub 3}-glycerol in porous and hydrophilic poly(vinylidene fluoride) (PVDF) substrate was experimentally studied. The effects of Na{sub 2}CO{sub 3} concentration, CO{sub 2} partial pressure, and feed stream relative humidity (RH) were investigated.

Chen, H.; Kovvali, A.S.; Majumdar, S.; Sirkar, K.K. [New Jersey Inst. of Tech., Newark, NJ (United States)] [New Jersey Inst. of Tech., Newark, NJ (United States)

1999-09-01

259

MOFs for CO2 capture and separation from flue gas mixtures: the effect of multifunctional sites on their adsorption capacity and selectivity.  

PubMed

Microporous metal-organic frameworks (MOFs) have attracted tremendous attention because of their versatile structures and tunable porosity that allow almost unlimited ways to improve their properties and optimize their functionality, making them very promising for a variety of important applications, especially in the adsorption and separation of small gases and hydrocarbons. Numerous studies have demonstrated that MOFs with multifunctional groups, such as open metal sites (OMSs) and Lewis basic sites (LBSs), interact strongly with carbon dioxide and are particularly effective in its capture and separation from binary mixtures of CO(2) and N(2). In this feature article, we briefly review the current state of MOF development in this area, with an emphasis on the effect of multifunctional groups on the selectivity and capacity of MOFs for the CO(2) capture from flue gas mixtures. PMID:23150882

Zhang, Zhijuan; Zhao, Yonggang; Gong, Qihan; Li, Zhong; Li, Jing

2013-01-25

260

Achieving Diameter-Selective Separation of Single-Walled Carbon Nanobutes by Using Polymer Conformation-Confined Helical Cavity.  

SciTech Connect

A water-soluble poly[(m-phenylenevinylene)-alt-(p-phenylenevinylene)] (PmPV) 2 has been synthesized, which exhibits an unsymmetrical substitution pattern on the para-phenylene unit. With one substituent being hydrophilic while the other being hydrophobic, the polymer chain has a higher tendency to fold in aqueous solution, thereby promoting the helical conformation. The polymer is found to selectively disperse the SWNTs of small diameters (d=0.75-0.84 nm), in sharp contrast to PmPV 1 with a symmetrical substitution pattern. The intriguing diameter-based selectivity is believed to be associated with the confined helical conformation, which provides a suitable cavity to host the SWNT of proper sizes. The study thus provides a useful demonstration that the polymer conformation can have a profound impact on the SWNT sorting.

Chen, Yusheng [University of Akron; Xu, Yongqian [University of Akron; Perry, Kelly A [ORNL; Sokolov, Alexei P [ORNL; More, Karren Leslie [ORNL; Pang, Yi [University of Akron

2012-01-01

261

Battery separator  

Microsoft Academic Search

A battery separator comprises a microporous sheet formed substantially of a mixture of polymeric constituents. One of the polymeric constituents is an ultrahigh-molecular-weight polyolefin having a standard load melt index of substantially 0 and an intrinsic viscosity greater than about 3.0. The other polymeric constituent is either a copolymer of an olefin and an ethylenically unsaturated monocarboxylic acid selected from

Versteegh

1977-01-01

262

Long-gradient separations coupled with selected reaction monitoring for highly sensitive, large scale targeted protein quantification in a single analysis  

PubMed Central

Long-gradient separations coupled to tandem MS were recently demonstrated to provide a deep proteome coverage for global proteomics; however, such long-gradient separations have not been explored for targeted proteomics. Herein, we investigate the potential performance of the long-gradient separations coupled with selected reaction monitoring (LG-SRM) for targeted protein quantification. Direct comparison of LG-SRM (5 h gradient) and conventional LC-SRM (45 min gradient) showed that the long-gradient separations significantly reduced background interference levels and provided an 8- to 100-fold improvement in LOQ for target proteins in human female serum. Based on at least one surrogate peptide per protein, an LOQ of 10 ng/mL was achieved for the two spiked proteins in non-depleted human serum. The LG-SRM detection of seven out of eight endogenous plasma proteins expressed at ng/mL or sub-ng/mL levels in clinical patient sera was also demonstrated. A correlation coefficient of >0.99 was observed for the results of LG-SRM and ELISA measurements for prostate-specific antigen (PSA) in selected patient sera. Further enhancement of LG-SRM sensitivity was achieved by applying front-end IgY14 immunoaffinity depletion. Besides improved sensitivity, LG-SRM potentially offers much higher multiplexing capacity than conventional LC-SRM due to an increase in average peak widths (~3-fold) for a 300-min gradient compared to a 45-min gradient. Therefore, LG-SRM holds great potential for bridging the gap between global and targeted proteomics due to its advantages in both sensitivity and multiplexing capacity. PMID:24004026

Shi, Tujin; Fillmore, Thomas L.; Gao, Yuqian; Zhao, Rui; He, Jintang; Schepmoes, Athena A.; Nicora, Carrie D.; Wu, Chaochao; Chambers, Justin L.; Moore, Ronald J.; Kagan, Jacob; Srivastava, Sudhir; Liu, Alvin Y.; Rodland, Karin D.; Liu, Tao; Camp, David G.; Smith, Richard D.; Qian, Wei-Jun

2013-01-01

263

Long-Gradient Separations Coupled with Selected Reaction Monitoring for Highly Sensitive, Large Scale Targeted Protein Quantification in a Single Analysis  

SciTech Connect

Long-gradient separations coupled to tandem MS were recently demonstrated to provide a deep proteome coverage for global proteomics; however, such long-gradient separations have not been explored for targeted proteomics. Herein, we investigate the potential performance of the long-gradient separations coupled with selected reaction monitoring (LG-SRM) for targeted protein quantification. Direct comparison of LG-SRM (5 h gradient) and conventional LC-SRM (45 min gradient) showed that the long-gradient separations significantly reduced background interference levels and provided an 8- to 100-fold improvement in LOQ for target proteins in human female serum. Based on at least one surrogate peptide per protein, an LOQ of 10 ng/mL was achieved for the two spiked proteins in non-depleted human serum. The LG-SRM detection of seven out of eight endogenous plasma proteins expressed at ng/mL or sub-ng/mL levels in clinical patient sera was also demonstrated. A correlation coefficient of >0.99 was observed for the results of LG-SRM and ELISA measurements for prostate-specific antigen (PSA) in selected patient sera. Further enhancement of LG-SRM sensitivity was achieved by applying front-end IgY14 immunoaffinity depletion. Besides improved sensitivity, LG-SRM offers at least 3 times higher multiplexing capacity than conventional LC-SRM due to ~3-fold increase in average peak widths for a 300-min gradient compared to a 45-min gradient. Therefore, LG-SRM holds great potential for bridging the gap between global and targeted proteomics due to its advantages in both sensitivity and multiplexing capacity.

Shi, Tujin; Fillmore, Thomas L.; Gao, Yuqian; Zhao, Rui; He, Jintang; Schepmoes, Athena A.; Nicora, Carrie D.; Wu, Chaochao; Chambers, Justin L.; Moore, Ronald J.; Kagan, Jacob; Srivastava, Sudhir; Liu, Alvin Y.; Rodland, Karin D.; Liu, Tao; Camp, David G.; Smith, Richard D.; Qian, Weijun

2013-10-01

264

Selective Separation of Scandium(III) and Yttrium(III) from other Rare Earth Elements using Cyanex302 as an Extractant  

Microsoft Academic Search

Liquid?liquid extraction and selective separation of scandium(III) and yttrium(III) with Cyanex302 (bis(2,4,4?trimethylpentyl)monothiophosphinic acid) has been carried out by controlling the aqueous phase pH. Scandium(III) and yttrium(III) were completely recovered from the organic phase using 5.0 M and 4.0 M nitric acid respectively and determined spectrophotometrically as their complexes with Arsenazo(III). The influence of extractant concentration, equilibration time, nature of diluents, stripping agents,

Manjusha Karve; Bhagyashree Vaidya

2008-01-01

265

Magnetic affinity microspheres with meso-/macroporous shells for selective enrichment and fast separation of phosphorylated biomolecules.  

PubMed

The flowerlike multifunctional affinity microspheres prepared by a facile solvothermal synthesis and subsequent calcination process consist of magnetic cores and hierarchical meso-/macroporous TiO2 shells. The hierarchical porous structure of the flowerlike affinity microspheres is constructed by the macroporous shell from the stacked mesoporous nanopetals which are assembled by small crystallites. The affinity microspheres have a relatively large specific surface area of 50.45 m(2) g(-1) and superparamagnetism with a saturation magnetization (Ms) value of 30.1 emu g(-1). We further demonstrate that they can be applied for rapid and effective purification of phosphoproteins, in virtue of their selective affinity, porous structure, and strong magnetism. In addition, the affinity microspheres can also be used for enrichment of phosphopeptides, and the selectivity is greatly improved due to the increase of mass transport and prevention of the possible "shadow effect" resulting from the smaller and deeper pores by taking advantage of the unique porous structure. Overall, this work will be highly beneficial for future applications in the isolation and identification of phosphorylated biomolecules. PMID:23514605

Cheng, Gong; Wang, Zhi-Gang; Liu, Yan-Lin; Zhang, Ji-Lin; Sun, De-Hui; Ni, Jia-Zuan

2013-04-24

266

Selective Separation of Cs and Sr from LiCl-Based Salt for Electrochemical Processing of Oxide Spent Nuclear Fuel  

SciTech Connect

Electrochemical processing technology is currently being used for the treatment of metallic spent fuel from the Experimental Breeder Reactor-II at Idaho National Laboratory. The treatment of oxide-based spent nuclear fuel via electrochemical processing is possible provided there is a front-end oxide reduction step. During this reduction process, certain fission products, including Cs and Sr, partition into the salt phase and form chlorides. Both solid state and molten LiCl-zeolite-A ion exchange tests were conducted for selectively removing Cs and Sr from LiCl-based salt. The solid-state tests produced in excess of 99% removal of Cs and Sr. The molten state tests failed due to phase transformation of the zeolite structure when in contact with the molten LiCl salt.

P Sachdev

2008-07-01

267

Shape-selective separation of polycyclic aromatic hydrocarbons by reversed-phase liquid chromatography on tetraphenylporphyrin-based stationary phases.  

PubMed

The reversed-phase chromatographic behavior of planar and non-planar polycyclic aromatic hydrocarbons (PAHs) is investigated on tetraphenylporphyrin and two metallotetraphenylporphyrin [Sn(IV), In(III)] bonded stationary phases using methanol-water and acetonitrile-water as mixed solvent mobile phases. Large differences in the capacity factors of aromatic solute pairs having the same number of carbon atoms, but differing in three-dimensional shape (e.g., triphenylene/o-terphenyl and perylene/alpha, alpha'-binaphthyl), suggest that the three tetraphenylporphyrin-based supports possess shape selectivity toward small planar aromatic solutes. Capacity factors for planar PAH solutes on these supports are significantly greater than for non-planar polyaryls having the same number of carbon atoms. PMID:8349741

Kibbey, C E; Meyerhoff, M E

1993-07-01

268

Selective ionic liquid ferrofluid based dispersive-solid phase extraction for simultaneous preconcentration/separation of lead and cadmium in milk and biological samples.  

PubMed

For the first time, a selective ionic liquid ferrofluid has been used in dispersive solid phase extraction (IL-FF-D-SPE) for simultaneous preconcentration and separation of lead and cadmium in milk and biological samples combined with flame atomic absorption spectrometry. To improve the selectivity of the ionic liquid ferrofluid, the surface of TiO2 nanoparticles with a magnetic core as sorbent was modified by loading 1-(2-pyridylazo)-2-naphtol. Due to the rapid injection of an appropriate amount of ionic liquid ferrofluid into the aqueous sample by a syringe, extraction can be achieved within a few seconds. In addition, based on the attraction of the ionic liquid ferrofluid to a magnet, no centrifugation step is needed for phase separation. The experimental parameters of IL-FF-D-SPE were optimized using a Box-Behnken design (BBD) after a Plackett-Burman screening design. Under the optimum conditions, the relative standard deviations of 2.2% and 2.4% were obtained for lead and cadmium, respectively (n=7). The limit of detections were 1.21µgL(-1) for Pb(II) and 0.21µgL(-1) for Cd(II). The preconcentration factors were 250 for lead and 200 for cadmium and the maximum adsorption capacities of the sorbent were 11.18 and 9.34mgg(-1) for lead and cadmium, respectively. PMID:25281121

Fasih Ramandi, Negin; Shemirani, Farzaneh

2015-01-01

269

Radiochemical scheme for the determination of molybdenum and uranium in biological materials by NAA  

Microsoft Academic Search

A new universal radiochemical separation scheme for selective and quantitative isolation of molybdenum and neptunium (formed from uranium), from neutron irradiated biological materials has been elaborated. The procedure is based on ion exchange and extraction chromatography with final fixation of molybdenum on a column with -benzoinoxime supported on Bio-Beads SM2 and neptunium on Dowex 1-X8 [No\\u000a3\\u000a–\\u000a]. The

B. Danko; R. Dybczy?ski

1995-01-01

270

Extraction of Uranium, Neptunium and Plutonium from Caustic Media  

SciTech Connect

5 Fundamental research on uranium, neptunium and plutonium separation from alkaline media using solvent extraction is being conducted. Specific extractants for these actinides from alkaline media have been synthesized to investigate the feasibility of selective removal of these elements. Two families of extractants have been studied: terephthalamide and tetra(hydroxybenzyl)ethylene diamine derivatives. Fundamental studies were conducted to characterize their extraction behavior from a wide variety of aqueous conditions. The terephthalamide derivatives exhibit a significant extraction strength along with a discriminatory behavior among the actinides, plutonium being extracted the most strongly. Quantitative extraction of plutonium and moderate extraction of neptunium and uranium was achieved from a simple caustic solution. Interestingly, strontium is also quantitatively extracted by these derivatives. However, their stability to highly caustic solutions still needs to be imp roved. Tetra(hydroxybenzyl)ethylene diamine derivatives exhibit a very good stability to caustic conditions and are currently being studied.

Delmau, Laetitia H.; Bonnesen, Peter V.; Engle, Nancy L.; Raymond, Kenneth N.; Xu, Jade

2004-03-28

271

Collision-Induced Release, Ion Mobility Separation, and Amino Acid Sequence Analysis of Subunits from Mass-Selected Noncovalent Protein Complexes  

NASA Astrophysics Data System (ADS)

In recent years, mass spectrometry has become a valuable tool for detecting and characterizing protein-protein interactions and for measuring the masses and subunit stoichiometries of noncovalent protein complexes. The gas-phase dissociation of noncovalent protein assemblies via tandem mass spectrometry can be useful in confirming subunit masses and stoichiometries; however, dissociation experiments that are able to yield subunit sequence information must usually be conducted separately. Here, we furnish proof of concept for a method that allows subunit sequence information to be directly obtained from a protein aggregate in a single gas-phase analysis. The experiments were carried out using a quadrupole time-of-flight mass spectrometer equipped with a traveling-wave ion mobility separator. This instrument configuration allows for a noncovalent protein assembly to be quadrupole selected, then subjected to two successive rounds of collision-induced dissociation with an intervening stage of ion mobility separation. This approach was applied to four model proteins as their corresponding homodimers: glucagon, ubiquitin, cytochrome c, and ?-lactoglobulin. In each case, b- and y-type fragment ions were obtained upon further collisional activation of the collisionally-released subunits, resulting in up to 50% sequence coverage. Owing to the incorporation of an ion mobility separation, these results also suggest the intriguing possibility of measuring complex mass, complex collisional cross section, subunit masses, subunit collisional cross sections, and sequence information for the subunits in a single gas-phase experiment. Overall, these findings represent a significant contribution towards the realization of protein interactomic analyses, which begin with native complexes and directly yield subunit identities.

Rathore, Deepali; Dodds, Eric D.

2014-09-01

272

Selective adsorption and separation of chromium (VI) on the magnetic iron-nickel oxide from waste nickel liquid.  

PubMed

The selective adsorption of Cr (VI) from the wastewater of Cr (VI)-Ni (II) by magnetically iron-nickel oxide was investigated in this study. Synthetic iron-nickel oxide magnetic particles in the co-sedimentation method were used as adsorbent to remove hexavalent chromium ions. The characteristic of adsorption was evaluated by Langmuir, Freundlich isotherm and Dubinin-Kaganer-Radushkevich (DKR) equations in the simulation wastewater of Cr (VI)-Ni (II) bi-system. The energy spectra and FT-IR analysis were used to test adsorbent before and after adsorption. The obtained results suggest that the uptake of chromium (VI) effect is obvious from phosphate anions and that from others is unobvious. The maximum adsorption capacity of hexavalent chromium is about 30 mg/g at pH 5.00+/-0.02, and it was reduced by increasing the total dissolved substance (TDS) of system. Adsorption energies E are about 10.310-21.321 kJ/mol which were obtained from DKR equation in difference TDS conditions. The regeneration shows that the iron-nickel oxide has good reuse performance and the hexavalent chromium was recycled. The major adsorption mechanism proposed was the ions exchange; however the surface coordination was a main role in the condition of TDS less than 200mg/L. PMID:18954940

Wei, Linsen; Yang, Gang; Wang, Ren; Ma, Wei

2009-05-30

273

Determination of suspended and dissolved uranium in water  

Microsoft Academic Search

Individual droplets of water can be analyzed for uranium down to less than 0.01 ..mu..g\\/l. using readily available neutron doses. By separately counting randomly arrayed and clustered tracks, the dissolved uranium can be separated from that which is suspended in particulate matter. (auth)

R. L. Fleischer; A. C. Delany

1976-01-01

274

Sensitive and selective flow injection analysis of hydrogen sulfite/sulfur dioxide by fluorescence detection with and without membrane separation by gas diffusion.  

PubMed

Highly sensitive and selective FIA flow injection analysis procedures for the determination of sulfite/hydrogen sulfite/sulfur dioxide were developed on the basis of an in situ-generated o-phthalaldehyde (OPA)/ammonium reagent and fluorescence detection. The highest sensitivity was achieved at an excitation wavelength of 330 nm, an emission wavelength of 390 nm, and at pH 6.5. Sulfite concentrations between 2.5 nM and 5 microM can be determined with relative standard deviations between 10.5 and 1.0% (n = 5, confidence level alpha = 0.05) by utilization of a reagent that contains 0.2 mM OPA and 0.4 M NH4Cl in 50 mM potassium phosphate buffer. A concentration of 0.1 mM sulfite can be selectively detected in the presence of thiosulfate, thioglycolate, tetrathionate, cysteine, and ascorbate. The fluorometric sulfite detection was combined with a membrane gas diffusion step to improve the selectivity with respect to nonvolatile fluorescing substances. The total sulfite content can be quantitatively separated as sulfur dioxide into an acceptor solution before its flow detection. Between 40 nM and 0.1 mM sulfite can be determined. After 1,000-fold dilution, the total sulfite content can be determined in white and red wines. PMID:11467572

Mana, H; Spohn, U

2001-07-01

275

Machining of uranium and uranium alloys  

SciTech Connect

Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures.

Morris, T.O.

1981-12-14

276

Uranium uptake by hydroponically cultivated crop plants.  

PubMed

Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC(50) value about 0.1mM. Cucumis sativa represented the most resistant plant to uranium (EC(50)=0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1mM or 0.5mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation. PMID:21486682

Soudek, Petr; Petrová, Sárka; Benešová, Dagmar; Dvo?áková, Marcela; Van?k, Tomáš

2011-06-01

277

A Geostatistical Study of the Uranium Deposit at Kvanefjeld,  

E-print Network

this problem appears to be a selective type of kriging. The overall uranium reserves are estimated as approx are identified by the discriminating effect of the individual variable. INIS descriptors; URANIUM ORES? RESERVESRisa-R-468 A Geostatistical Study of the Uranium Deposit at Kvanefjeld, The Ilimaussaq Intrusion

278

Establishment of a search library about benzylisoquinoline alkaloids based on selective separation on the binaphthyl column and standard analysis on C18 column.  

PubMed

A search library about benzylisoquinoline alkaloids was established based on preparation of alkaloid fractions from Rhizoma coptidis, Cortex phellodendri, and Rhizoma corydalis. In this work, two alkaloid fractions from each herbal medicine were first prepared based on selective separation on the "click" binaphthyl column. And then these alkaloid fractions were analyzed on C18 column by liquid chromatography coupled with tandem mass spectrometry. Many structure-related compounds were included in these alkaloids fractions, which led to easy separation and good MS response in further work. Therefore, a search library of 52 benzylisoquinoline alkaloids was established, which included eight aporphine, 19 tetrahydroprotoberberine, two protopine, two benzyltetrahydroisoquinoline, and 21 protoberberine alkaloids. The information of the search library contained compound names, structures, retention times, accurate masses, fragmentation pathways of benzylisoquionline alkaloids, and their sources from three herbal medicines. Using such a library, the alkaloids, especially those trace and unknown components in some herbal medicine could be accurately and quickly identified. In addition, the distribution of benzylisoquinoline alkaloids in the herbal medicines could be also summarized by searching the source samples in the library. PMID:23109405

Liu, Qiaoxia; Zhou, Binbin; Wang, Xinliang; Ke, Yanxiong; Jin, Yu; Yin, Lihui; Liang, Xinmiao

2012-12-01

279

Yolk-Shell Nanostructured Fe3O4@NiSiO3 for Selective Affinity and Magnetic Separation of His-Tagged Proteins.  

PubMed

Recent developments of nanotechnology encourage novel materials for facile separations and purifications of recombinant proteins, which are of great importance in disease diagnoses and treatments. We find that Fe3O4@NiSiO3 with yolk-shell nanostructure can be used to specifically purify histidine-tagged (His-tagged) proteins from mixtures of lysed cells with a recyclable process. Each individual nanoparticle composes by a mesoporous nickel silicate shell and a magnetic Fe3O4 core in the hollow inner, which is featured by its great loading efficiency and rapid response toward magnetic fields. The abundant Ni(2+) cations on the shell provide docking sites for selective coordination of histidine and the reversible release is induced by excess imidazole solution. Because of the Fe3O4 cores, the separation, concentration, and recycling of the nanocomposites become feasible under the controls of magnets. These characteristics would be highly beneficial in nanoparticle-based biomedical applications for targeted-drug delivery and biosensors. PMID:25303145

Wang, Yang; Wang, Guangchuan; Xiao, Yun; Yang, Yuling; Tang, Ruikang

2014-11-12

280

Uranium industry annual 1996  

SciTech Connect

The Uranium Industry Annual 1996 (UIA 1996) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1996 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. Data on uranium raw materials activities for 1987 through 1996 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2006, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. A feature article, The Role of Thorium in Nuclear Energy, is included. 24 figs., 56 tabs.

NONE

1997-04-01

281

Uranium industry annual, 1991  

SciTech Connect

In the Uranium Industry Annual 1991, data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2. A feature article entitled ``The Uranium Industry of the Commonwealth of Independent States`` is included in this report.

Not Available

1992-10-01

282

Uranium industry annual, 1991  

SciTech Connect

In the Uranium Industry Annual 1991, data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2. A feature article entitled The Uranium Industry of the Commonwealth of Independent States'' is included in this report.

Not Available

1992-10-01

283

Plant-Uptake of Uranium: Hydroponic and Soil System Studies  

Microsoft Academic Search

Limited information is available on screening and selection of terrestrial plants for uptake and translocation of uranium from soil. This article evaluates the removal of uranium from water and soil by selected plants, comparing plant performance in hydroponic systems with that in two soil systems (a sandy-loam soil and an organic-rich soil). Plants selected for this study were Sunflower (Helianthus

Anu Ramaswami; Paul Carr; Mark Burkhardt

2001-01-01

284

Uranium Ore Uranium is extracted  

E-print Network

reaction. Generation of Electricity at Nuclear Power Plants Electricity is generated by nuclear power is concentrated in a solid substance called"yellowcake." Chemical Conversion Plants convert the uranium plants with reactors that use water for moderating nuclear reactions and cooling. Spent Nuclear Fuel Used

285

Geometallurgy of uranium deposits  

Microsoft Academic Search

Mineralogical controls exert significant control over the extraction of uranium from its ores. Uranium speciation, associated mineralogy, deportment and uranium mineral availability are all factors for consideration when assessing leachability. This study presents data from laboratory uranium extractions undertaken on several contrasting uranium ores from a wide range of orebodies. The results provide insight into the mineralogical factors of importance

R. J. Bowell; J. Grogan; M. Hutton-Ashkenny; C. Brough; K. Penman; D. J. Sapsford

2011-01-01

286

A separability parameter for dielectrophoretic cell separation.  

PubMed

In this study, a separability parameter is introduced to determine the selection of optimum operating parameters for DEP separation of a cell pair. The separability parameter is defined as a function of cells' Clausius-Mossotti (CM) factors. T-cell leukemia Jurkat and mouse melanoma B16 cells are tested to validate the separability parameter. CM factors of cells are measured using a recently developed microfluidic impedance spectroscopy device. Separability maps are generated for varying values of field frequency and buffer conductivity. Cell separation is tested using a planar interdigitated electrode array at different buffer conductivities. Impedance measurements of the DEP device are performed at various buffer conductivities. Electrode polarization effects and energy allocation for dielectrophoretic manipulation of cells are computed from the impedance data utilizing an equivalent circuit model. Cell separation results are explained in the light of the impedance measurements. PMID:23348751

Sabuncu, Ahmet C; Beskok, Ali

2013-04-01

287

Selective separation of uranyl ion from TRU`s in a combined solvent extraction process using tetrahydrofuran-2,3,4,5-tetracarboxylic acid  

SciTech Connect

Selective partitioning of uranyl from transuranic elements in a solvent extraction system which employs a neutral organophosphorus extractant and an aqueous complexant has been demonstrated in a previous report. The extractant solution combines octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO), diamyl(amyl)phosphonate (or tributylphosphate), and di(t-butylcyclohexano)-18-crown-6 in Isopar L, and is designed for simultaneous removal of strontium, technetium, lanthanides and actinides from radioactive wastes. The aqueous complexant is tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA). In this report, the separation of UO{sub 2}{sup 2+} from Np(IV), Eu(III), Am(III), and Pu(IV) using the Combined Process Solvent has been optimized. Potentiometric titration and NMR spectroscopic results describe the distribution of THFTCA into the organic phase as a function of acidity and [THFTCA]. Further potentiometric titration experiments have determined the stoichiometry and stability of uranyl complexes in the aqueous phase. The thermodynamic data indicate that the uranyl complexes are anomalously weak which partially accounts for the selectivity. Ternary complexes involving UO{sub 2}{sup 2+}, CMPO, and THFTCA in the extractant phase also appear to play a role. 13 refs., 6 figs., 1 tab.

Nash, K.L.; Horwitz, E.P.; Diamond, H.; Rickert, P.G.; Muntean, J.V.; Mendoza, M.D.; Giuseppe, G. di [Argonne National Lab., IL (United States)

1996-01-01

288

Novel microorganism for selective separation of coal from ash and pyrite. Sixth quarterly technical progress report, January 1, 1995--March 31, 1995  

SciTech Connect

The objective of this research project is to study the effectiveness of a novel hydrophobic microorganism, Mycobacterium phlei (M. phlei), for the selective flocculation of coal from pyrite and ash forming minerals. During the reporting period, the flocculation efficiencies of Illinois No. 6 and KY No. 9 coal in the presence of whole and ruptured cells of M. phlei were studied. The effect of synthetic flocculants were also studied for comparison at selected pH values. Results showed that the whole cells of M. phlei can flocculate coal very effectively and rapidly for both the coal samples. However, with ruptured cells of M. phlei the flocculation efficiency is significantly less which can be attributed to the loss of extracellular surfactants during rupturing. Separation of flocs using column flotation was studied for both the coal samples in the acidic pH range. Results indicated that excellent rejection of pyritic sulfur and ash could be obtained with a high combustible recovery. DLVO calculations were performed for all the minerals used in this study to calculate the interaction energies in the presence of whole cells and ruptured cells of M. phlei. A minimum in interaction energy is observed between coal and whole cells of M. phlei at pH 4 which is probably responsible for the higher adhesion and flocculation efficiencies at the pH. However, with ruptured cells the interaction energy increases thus decreasing the amount of M. phlei cells adhering to the surface.

Misra, M.; Smith, R.W.; Raichur, A.M.

1995-08-01

289

Method development and validation for optimized separation of quercetin derivatives in selected Potentilla species using high-performance thin-layer chromatography photodensitometry method.  

PubMed

A novel HPTLC-densitometry method was developed for separation and quantitative determination of four flavonoids: quercetin 3-O-?-d-glucuropyranoside (miquelianin; QG), quercetin 3-O-?-d-glucopyranoside (isoquercitrin; IQ), quercetin 3-O-?-d-galactopyranoside (hyperoside; HYP) and quercetin 3-O-?-d-(6?-?-l-rhamnosylo)-glucopyranoside (rutin; RUT) in ethyl acetate fractions from aerial parts of selected Potentilla species: P. argentea, P. erecta, Dasiphora fruticosa (syn. P. fruticosa), Drymocallis rupestris (syn. P. rupestris), P. nepalensis var. 'Miss Wilmott' and P. thuringiaca. For the first time, separation of this type of flavonoids was achieved on a HPTLC DIOL F(254) plates using a mixture consisting of ethyl acetate/methyl ethyl ketone/diisopropyl ether/formic acid (3:10:4:1, v/v/v/v). QG, IQ, HYP and RUT were determined by densitometry at 363 nm. Sensitivity, accuracy (recovery rates were between 95.0 and 101.4%) and precision (in both cases intra-day precision and inter-day precision were ? 8.0%) of the method were determined. Their amounts were calculated using the regression equations of the calibration curves which were linear in a range of 0.025-0.200 ?g/spot for all investigated compounds. The amounts of marker compounds in ethyl acetate extracts of Potentilla species measured by the method ranged between 16.7 ± 1.1 and 41.7 ± 0.6 mg/g for QG, 15.8 ± 1.3 and 36.7 ± 1.0mg/g for IQ, 14.5 ± 0.5mg/g for HYP and 6.7 ± 0.3 and 27.8 ± 2.1mg/g for RUT. The method was found to be relatively simple, specific, precise and accurate and may be used for the quality control of simultaneous determination of quercetin derivatives in Potentilla extracts but also in other similar plant materials. PMID:22209482

Tomczyk, Micha?; Bazylko, Agnieszka; Bonarewicz, Jessica

2012-03-01

290

Laser separation of medical isotopes  

Microsoft Academic Search

There is an increasing demand for different separated isotopes as feed material for reactor and cyclotron-produced radioisotopes used by a fast-growing radiopharmaceutical industry. One new technology that may meet future demands for medical isotopes is molecular laser isotope separation (MLIS). This method was investigated for the enrichment of uranium in the 1970`s and 1980s by Los Alamos National Laboratory, Isotope

J. W. Eerkens; D. A. Puglishi; W. H. Miller

1996-01-01

291

URANIUM IN ALKALINE ROCKS  

E-print Network

GENERAL Significant reserves of uranium have been identifieduranium deposit at Kvanefjeld, the Ilimaussaq intrusion, South Greenland, geology, reservesreserves well in excess of ten thousand tons of uranium

Murphy, M.

2011-01-01

292

Investigation of matrix effects and isotope dilution in SIMS measurement of uranium in soils  

NASA Astrophysics Data System (ADS)

The characteristics of sputter-initiated resonance ionization spectroscopy (SIRIS) for determining trace uranium concentrations in soils are investigated. Although, presently, the most formidable problem in the assay of environmental materials with SIRIS is the low sensitivity of the system, we have chosen to focus on matrix effects as possible limiting factors in this paper. Separate active efforts are being made to improve sensitivity and isotopic selectivity in RIS systems. Electrically conducting solid samples compatible with high vacuum are made by compacting soil with 15% or greater graphite binder. It is found that matrix effects on the absolute uranium SIRIS signals can be as large as two orders of magnitude, precluding a direct comparison of uranium concentrations through uranium SIRIS signal levels. The method of isotope dilution is also explored. Systematic errors caused by different molecular forms or different microscopic physical locations of the two isotopes are less than 30% in this method. It is found that for samples in which these effects are minimized, the capability of the instrument is such that uranium concentrations can be determined successfully to better than 10% accuracy.

Hutchinson, J. M. R.; Inn, K. G. W.; Parks, J. E.; Beekman, D. W.; Spaar, M. T.; Fairbank, W. M.

1987-06-01

293

Diffusion and Leaching of Selected Radionuclides (Iodine-129, Technetium-99, and Uranium) Through Category 3 Waste Encasement Concrete and Soil Fill Material  

SciTech Connect

An assessment of long-term performance of Category 3 waste-enclosing cement grouts requires data about the leachability/diffusion of radionuclide species (iodine-129, technetium-99, and uranium) when the waste forms come in contact with groundwater. Leachability data were collected by conducting dynamic (ANS-16.1) and static leach tests on radionuclide-containing cement specimens. The diffusivity of radionuclides in soil and concrete media was collected by conducting soil-soil and concrete-soil half-cell experiments.

Mattigod, Shas V.; Whyatt, Greg A.; Serne, R. Jeffrey; Martin, P. F.; Schwab, Kristen E.; Wood, Marcus I.

2001-09-24

294

Interplay of metalloligand and organic ligand to tune micropores within isostructural mixed-metal organic frameworks (M'MOFs) for their highly selective separation of chiral and achiral small molecules.  

PubMed

Four porous isostructural mixed-metal-organic frameworks (M'MOFs) have been synthesized and structurally characterized. The pores within these M'MOFs are systematically tuned by the interplay of both the metalloligands and organic ligands which have enabled us not only to direct their highly selective separation of chiral alcohols 1-phenylethanol (PEA), 2-butanol (BUT), and 2-pentanol (2-PEN) with the highest ee up to 82.4% but also to lead highly selective separation of achiral C(2)H(2)/C(2)H(4) separation. The potential application of these M'MOFs for the fixed bed pressure swing adsorption (PSA) separation of C(2)H(2)/C(2)H(4) has been further examined and compared by the transient breakthrough simulations in which the purity requirement of 40 ppm in the outlet gas can be readily fulfilled by the fixed bed M'MOF-4a adsorber at ambient conditions. PMID:22545712

Das, Madhab C; Guo, Qunsheng; He, Yabing; Kim, Jaheon; Zhao, Cong-Gui; Hong, Kunlun; Xiang, Shengchang; Zhang, Zhangjing; Thomas, K Mark; Krishna, Rajamani; Chen, Banglin

2012-05-23

295

Advanced reactor design study. Assessing nonbackfittable concepts for improving uranium utilization in light water reactors  

SciTech Connect

The objective of the Advanced Reactor Design Study (ARDS) is to identify and evaluate nonbackfittable concepts for improving uranium utilization in light water reactors (LWRs). The results of this study provide a basis for selecting and demonstrating specific nonbackfittable concepts that have good potential for implementation. Lead responsibility for managing the study was assigned to the Pacific Northwest Laboratory (PNL). Nonbackfittable concepts for improving uranium utilization in LWRs on the once-through fuel cycle were selected separately for PWRs and BWRs due to basic differences in the way specific concepts apply to those plants. Nonbackfittable concepts are those that are too costly to incorporate in existing plants, and thus, could only be economically incorporated in new reactor designs or plants in very early stages of construction. Essential results of the Advanced Reactor Design Study are summarized.

Fleischman, R.M.; Goldsmith, S.; Newman, D.F.; Trapp, T.J.; Spinrad, B.I.

1981-09-01

296

Uranium(VI) organoimido complexes  

SciTech Connect

Complexes containing multiply bonded alkylidene, alkylidyne, imido, nitrido, and oxo ligands, and selected combinations thereof, are part of the tapestry of tungsten(VI) chemistry. Aside from uranyl complexes, the only reported molecular coordination compounds of U(VI) are UF{sub 6}, UCl{sub 6}, and the binary alkoxides, U(OR){sub 6}. Uranium(VI) compounds containing the other functional groups listed above have never been reported. Here the authors describe the synthesis and structural characterization of the first uranium(VI) systems containing a multiple bond to nitrogen.

Burns, C.J.; Smith, W.H.; Sattelberger, A.P. (Los Alamos National Lab., NM (USA)); Huffman, J.C. (Indiana Univ., Bloomington (USA))

1990-04-11

297

Dynamic Properties of Shock Loaded Uranium Foils  

NASA Astrophysics Data System (ADS)

A series of spall experiments have been completed with thin depleted uranium targets. The samples were nominally 0.1 mm thick. The first set of uranium spall targets were rolled to final thickness from low purity uranium. Samples for the second set were cut and ground to their final thickness from high purity (electro-refined) cast uranium. The impactors for these experiments were laser-launched 0.05 mm thick copper flyers, which were 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium spall targets, from deformation to complete spall or separation at higher velocities. Dynamic measurements of the uranium targets free surface velocity were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles and spall strengths (estimated from the magnitude of the pull-back signals), are discussed and compared with the micro-structural evidence of spall from the sectioned uranium targets.

Robbins, David; Alexander, David; Hanrahan, Robert; Kelly, Ann; Snow, Ronny; Stahl, David; Sheffield, Stephen; Gehr, Russell; Rupp, Ted

2001-06-01

298

Plutonium recovery from spent reactor fuel by uranium displacement  

SciTech Connect

This report discusses a process for separating uranium values and transuranic values from fission products containing rare earth values when the values which are contained together in a molten chloride salt electrolyte. A molten chloride salt electrolyte with a first ratio of plutonium chloride to uranium chloride is contacted with both a solid cathode and an anode having values of uranium and fission products including plutonium. A voltage is applied across the anode and cathode electrolytically to transfer uranium and plutonium from the anode to the electrolyte while uranium values in the electrolyte electrolytically deposit as uranium metal on the solid cathode in an amount equal to the uranium and plutonium transferred from the anode causing the electrolyte to have a second ratio of plutonium chloride to uranium chloride. Then the solid cathode with the uranium metal deposited thereon is removed and molten cadmium having uranium dissolved therein is brought into contact with the electrolyte resulting in chemical transfer of plutonium values from the electrolyte to the molten cadmium and transfer of uranium values from the molten cadmium to the electrolyte until the first ratio of plutonium chloride to uranium chloride is re-established.

Ackerman, J.P.

1991-01-01

299

HYDROXYLAMINE DERIVATIVE IN PUREX PROCESS. VI. STUDY ON THE PARTITION OF URANIUM\\/NEPTUNIUM AND URANIUM\\/PLUTONIUM WITH N,N-DIETHYLHYDROXYLAMINE IN THE PURIFICATION CYCLE OF URANIUM CONTACTOR  

Microsoft Academic Search

Cascade extraction of uranium and cascade extraction-separation of uranium\\/neptunium and uranium\\/plutonium with 6 extraction stages and 6 stripping stages have been studied in the presence of N,N-diethylhydroxylamine (abbreviated as DEHAN) in nitric acid medium according to the experimental conditions of the purification cycle of uranium (referred to as contactor 2D) of the second cycle of the Purex Process. The percent

Zhang Anyun; Hu Jingxin; Zhang Xianye; Wang Fangding

2001-01-01

300

Issues in uranium availability  

Microsoft Academic Search

The purpose of this publication is to show the process by which information about uranium reserves and resources is developed, evaluated and used. The following three papers in this volume have been abstracted and indexed for the Energy Data Base: (1) uranium reserve and resource assessment; (2) exploration for uranium in the United States; (3) nuclear power, the uranium industry,

J. J. Jr. Schanz; S. S. Adams; R. L. Gordon

1982-01-01

301

Method for fabricating laminated uranium composites  

DOEpatents

The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

Chapman, L.R.

1983-08-03

302

Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Slick Rock, Colorado: Remedial Action Selection Report. Preliminary final  

SciTech Connect

This proposed remedial action plan incorporates the results of detailed investigation of geologic, geomorphic, and seismic conditions at the proposed disposal site. The proposed remedial action will consist of relocating the uranium mill tailings, contaminated vicinity property materials, demolition debris, and windblown/waterborne materials to a permanent repository at the proposed Burro Canyon disposal cell. The proposed disposal site will be geomorphically stable. Seismic design parameters were developed for the geotechnical analyses of the proposed cell. Cell stability was analyzed to ensure long-term performance of the disposal cell in meeting design standards, including slope stability, settlement, and liquefaction potential. The proposed cell cover and erosion protection features were also analyzed and designed to protect the RRM (residual radioactive materials) against surface water and wind erosion. The location of the proposed cell precludes the need for permanent drainage or interceptor ditches. Rock to be used on the cell top-, side-, and toeslopes was sized to withstand probable maximum precipitation events.

Not Available

1994-03-01

303

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

SciTech Connect

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

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

1983-01-01

304

Separations inside a cube  

E-print Network

Two points are randomly selected inside a three-dimensional euclidian cube. The value l of their separation lies somewhere between zero and the length of a diagonal of the cube. The probability density P(l) of the separation is obtained analytically. Also a Monte Carlo computer simulation is performed, showing good agreement with the formulas obtained.

A. F. F. Teixeira

2001-12-28

305

Morphologies of uranium and uranium zirconium electrodeposits  

NASA Astrophysics Data System (ADS)

Uranium and uranium-zirconium electrodeposits produced in the Fuel Cycle Facility at Argonne National Laboratory-West were examined using standard metallurgical techniques. Substantial differences in the morphologies of the two types of deposits were observed. Samples from pure uranium deposits were comprised of chains of uranium crystals with a characteristic rhomboidal shape, while the morphologies of samples from deposits containing zirconium in excess of approximately 0.5 wt% showed more polycrystalline features. Zirconium was found to be present as a second, zirconium metal phase at or very near the uranium-zirconium dendrite surfaces. Higher collection efficiencies and total deposit weights were observed for the uranium-zirconium deposits; this performance increase is likely a result of better mechanical properties exhibited by the uranium-zirconium dendrite morphology.

Totemeier, Terry C.; Mariani, Robert D.

1997-12-01

306

New separators for battery systems  

Microsoft Academic Search

The reported study takes into consideration separators for miniature cells, such as silver\\/zinc button cells, and separators for aircraft nickel\\/cadmium batteries. It is pointed out that separators for energy systems having an aqueous electrolyte, either acid or basic, can be prepared by selective modification of radiation grafting parameters. A new family of separators, known as the 'SC' series, has been

J. Lee; V. Dagostino

1981-01-01

307

Process modeling of in-situ electrochemical partitioning of uranium and plutonium in purex process: benchmark results with uranium reduction  

Microsoft Academic Search

In-situ reduction of plutonium and uranium for the separation of U\\/Pu is suitable for plutonium-rich fuels such as FBR fuels. The mathematical basis for a computer program PUSEP (Plutonium Uranium Solvent Extraction Program) for the analysis of partitioning cycle of PUREX process involving in-situ electrochemical reduction of uranium and plutonium is described in the present investigation. Model equations have been

V. Reshmi; N. K. Pandey; R. Sivasubramanian; S. Ganesh; M. K. Ahmed; U. Kamachi Mudali; R. Natarajan

2012-01-01

308

Magnetic separation for soil decontamination  

SciTech Connect

High gradient magnetic separation (HGMS) is a physical separation process that is used to extract magnetic particles from mixtures. The technology is used on a large scale in the kaolin clay industry to whiten or brighten kaolin clay and increase its value. Because all uranium and plutonium compounds are slightly magnetic, HGMS can be used to separate these contaminants from non-magnetic soils. A Cooperative Research and Development Agreement (CRADA) was signed in 1992 between Los Alamos National Laboratory (LANL) and Lockheed Environmental Systems and Technologies Company (LESAT) to develop HGMS for soil decontamination. This paper reports progress and describes the HGMS technology.

Avens, L.R.; Worl, L.A.; deAguero, K.J.; Padilla, D.D.; Prenger, F.C.; Stewart, W.F.; Hill, D.D. [Los Alamos National Lab., NM (United States); Tolt, T.L. [Lockheed Environmental Systems and Technologies (United States)

1993-02-01

309

Magnetic separation for soil decontamination  

SciTech Connect

High gradient magnetic separation (HGMS) is a physical separation process that is used to extract magnetic particles from mixtures. The technology is used on a large scale in the kaolin clay industry to whiten or brighten kaolin clay and increase its value. Because all uranium and plutonium compounds are slightly magnetic, HGMS can be used to separate these contaminants from non-magnetic soils. A Cooperative Research and Development Agreement (CRADA) was signed in 1992 between Los Alamos National Laboratory (LANL) and Lockheed Environmental Systems and Technologies Company (LESAT) to develop HGMS for soil decontamination. This paper reports progress and describes the HGMS technology.

Avens, L.R.; Worl, L.A.; deAguero, K.J.; Padilla, D.D.; Prenger, F.C.; Stewart, W.F.; Hill, D.D. (Los Alamos National Lab., NM (United States)); Tolt, T.L. (Lockheed Environmental Systems and Technologies (United States))

1993-01-01

310

Process for recovering niobium from uranium-niobium alloys  

DOEpatents

Niobium is recovered from scrap uranium-niobium alloy by melting the scrap with tin, solidifying the billet thus formed, heating the billet to combine niobium with tin therein, placing the billet in hydrochloric acid to dissolve the uranium and leave an insoluble residue of niobium stannide, then separating the niobium stannide from the acid.

Wallace, Steven A. (Knoxville, TN); Creech, Edward T. (Oak Ridge, TN); Northcutt, Walter G. (Oak Ridge, TN)

1983-01-01

311

Whole-rock uranium analysis by fission track activation  

NASA Technical Reports Server (NTRS)

We report a whole-rock uranium method in which the polished sample and track detector are separated in a vacuum chamber. Irradiation with thermal neutrons induces uranium fission in the sample, and the detector records the integrated fission track density. Detection efficiency and geometric factors are calculated and compared with calibration experiments.

Weiss, J. R.; Haines, E. L.

1974-01-01

312

separationsNOW.com  

NSDL National Science Digital Library

This separation science and chromatography Web portal from publisher John Wiley and Sons expects "to become the definitive separation science resource on the Internet, offering a wealth of valuable information, resources, and services." separationsNOW addresses electrophoresis, chromatography, and other separation techniques with frequently-updated news, Web links, conference announcements, technique-specific discussion forums, educational features, and much more. Free registration is required to access advanced features, such as a selection of free full-text articles in the online library.

2003-01-01

313

separationsNOW.com  

NSDL National Science Digital Library

This separation science and chromatography Web portal from publisher John Wiley and Sons expects "to become the definitive separation science resource on the Internet, offering a wealth of valuable information, resources, and services." separationsNOW addresses electrophoresis, chromatography, and other separation techniques with frequently-updated news, Web links, conference announcements, technique-specific discussion forums, educational features, and much more. Free registration is required to access advanced features, such as a selection of free full-text articles in the online library.

2005-12-05

314

Uranium mineralization in southern Victoria Land, Antarctica  

SciTech Connect

For the past 10 antarctic field seasons, an airborne gamma-ray spectrometric survey has been conducted over widely separated parts of the continent. Localized accumulations of both primary and secondary uranium minerals have been discovered at several localities scattered along the Transantarctic Mountains from the Scott Glacier to northern Victoria Land. A number of highly significant radiation anomalies have been discovered in the area between the Koettlitz Glacier and the Pyramid Trough. The occurrences consist of pegmatite vein complexes which contain an association of primary uranium and thorium minerals. Of still greater significance is the fact that abundant secondary uranium minerals were found in association with the primary deposits, and they indicate clearly that uranium is geochemically mobile under the conditions imposed by the arid polar climate that now exists in southern Victoria Land. Preliminary results of a uranium analysis performed by neutron activation indicate a concentration of 0.12% uranium in a composite sample from the two veins. Even higher levels of thorium are present. The nature of the primary uranium mineralization is currently under investigation. Preliminary results are discussed.

Dreschhoff, G.A.M.; Zeller, E.J.

1986-01-01

315

Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Slick Rock, Colorado. Remedial action selection report, Appendix B  

SciTech Connect

The Slick Rock uranium mill tailings sites are located near the small town of Slick Rock, in San Miguel County, Colorado. There are two designated UMTRA sites at Slick Rock, the Union Carbide (UC) site and the North Continent (NC) site. Both sites are adjacent to the Dolores River. The UC site is approximately 1 mile (mi) [2 kilometers (km)] downstream of the NC site. Contaminated materials cover an estimated 55 acres (ac) [22 hectares (ha)] at the UC site and 12 ac (4.9 ha) at the NC site. The sites contain former mill building concrete foundations, tailings piles, demolition debris, and areas contaminated by windblown and waterborne radioactive materials. The total estimated volume of contaminated materials is approximately 620, 000 cubic yards (yd{sup 3}) [470,000 cubic meters (m{sup 3})]. In addition to the contamination at the two processing site areas, four vicinity properties were contaminated. Contamination associated with the UC and NC sites has leached into groundwater.

Not Available

1993-07-01

316

Detection of depleted uranium in urine of veterans from the 1991 Gulf War.  

PubMed

American soldiers involved in "friendly fire" accidents during the 1991 Gulf War were injured with depleted-uranium-containing fragments or possibly exposed to depleted uranium via other routes such as inhalation, ingestion, and/or wound contamination. To evaluate the presence of depleted uranium in these soldiers eight years later, the uranium concentration and depleted uranium content of urine samples were determined by inductively coupled plasma mass spectrometry in (a) depleted uranium exposed soldiers with embedded shrapnel, (b) depleted uranium exposed soldiers with no shrapnel, and (c) a reference group of deployed soldiers not involved in the friendly fire incidents. Uranium isotopic ratios measured in many urine samples injected directly into the inductively coupled plasma mass spectrometer and analyzed at a mass resolution m/delta m of 300 appeared enriched in 235U with respect to natural abundance (0.72%) due to the presence of an interference of a polyatomic molecule of mass 234.81 amu that was resolved at a mass resolution m/delta m of 4,000. The 235U abundance measured on uranium separated from these urines by anion exchange chromatography was clearly natural or depleted. Urine uranium concentrations of soldiers with shrapnel were higher than those of the two other groups, and 16 out of 17 soldiers with shrapnel had detectable depleted uranium in their urine. In depleted uranium exposed soldiers with no shrapnel, depleted uranium was detected in urine samples of 10 out of 28 soldiers. The median uranium concentration of urines with depleted uranium from soldiers without shrapnel was significantly higher than in urines with no depleted uranium, though substantial overlap in urine uranium concentrations existed between the two groups. Accordingly, assessment of depleted uranium exposure using urine must rely on uranium isotopic analyses, since urine uranium concentration is not an unequivocal indicator of depleted uranium presence in soldiers with no embedded shrapnel. PMID:14695004

Gwiazda, R H; Squibb, K; McDiarmid, M; Smith, D

2004-01-01

317

Processes for extraction of uranium and radium from uranium-containing ores using ferric nitrate  

SciTech Connect

A process is described for the extraction of both uranium and radium from uranium ores in the presence of an interfering sulfate ion resulting from the presence of sulfide therein by use of an aqueous ferric nitrate leachant including the steps of: (a) mechanically treating the finely ground ore for the removal of sulfide therefrom; (b) leaching the mechanically treated finely ground ore with aqueous acidic ferric nitrate solution in a concentration from 0.01 to 0.1M for the removal of uranium and radium therefrom to result in a liquid ferric nitrate leachate containing radium and uranium and a wet cake containing radium, uranium and ferric nitrate; (c) treating the ferric nitrate leachate to separate uranium and radium therefrom; (d) separately treating the wet cake for removal of retained ferric nitrate and the residual radium and uranium therefrom; and (e) recirculating a major portion of the ferric nitrate leachate from step (c) for the leaching of more of the mechanically treated finely ground ore.

Nirdosh, I.

1987-03-10

318

The Recovery of Trace Thorium from Large Quantities of Uranium  

Microsoft Academic Search

This work describes the chromatographic separation of trace amounts of Thorium (mg or less) from large quantities of Uranium (g or kg). The separation method employs extraction chromatographic materials containing tetra(n?octyl)diglycolamide (TODGA) and quaternary amine extractants. Applications of this separation include isolation of Th from U and Th from U. Th could be a useful radiotracer, providing a continuous supply

E. Philip Horwitz; Daniel R. McAlister

2009-01-01

319

Determination of rare-earth elements in uranium-bearing materials by inductively coupled plasma mass spectrometry.  

PubMed

A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-earth elements) in uranium-bearing materials by inductively coupled plasma sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg g(-1) range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology. PMID:20152406

Varga, Zsolt; Katona, Róbert; Stefánka, Zsolt; Wallenius, Maria; Mayer, Klaus; Nicholl, Adrian

2010-03-15

320

Battery separators  

Microsoft Academic Search

A novel, improved battery separator and process for making the separator. Essentially, the separator carries a plurality of polymeric ribs bonded to at least one surface and the ribs have alternating elevated segments of uniform maxiumum heights and depressed segments along the length of the ribs.

R. Le Bayon; R. Faucon; J. Legrix

1984-01-01

321

Battery separator  

Microsoft Academic Search

A battery separator is described that is embossed with a configuration that is neither vertical corrugation or vertical rib and yet in which all of the surface areas of the two separator faces open or slant upwardly except the portions actually directly engaged against a battery plate. Thus all intended recesses in the faces of the battery separator are open

N. J. Lin; D. D. ORell

1980-01-01

322

Battery separator  

Microsoft Academic Search

The instant invention is directed to a sheet product capable of forming an improved battery separator. The present sheet product is formed from a thin, acid-stable, porous material and has a first and a second major face with a plurality of separate, continuous, open channels on each face such that each channel on each major face defines a separation between

N. J. Lin; D. D. Orell

1983-01-01

323

Pattern recognition applied to uranium prospecting  

Microsoft Academic Search

PATTERN recognition techniques provide one way of uniting quantitative and descriptive geologic data for mineral prospecting. A quantified decision process using computer-selected patterns of geologic data has the potential of selecting areas with undiscovered deposits of uranium or other minerals. When a natural resource is mined more rapidly than it is discovered, its continued production becomes increasingly difficult. For example,

P. L. Briggs

1977-01-01

324

Mineralogical analysis and uranium distribution of the sediments from the upper Jackson formation, Karnes County, Texas  

E-print Network

and illite. Moreover, smectite in the samples is relatively highly expandable; thus, the adsorption of uranium by smectite into interlayer positions could have played a significant role in uranium mineralization. ACKNOWLEDGMENTS I would like to thank..., mineralogy and stratigraphy of uranium ore bodies. Finally, an analysis of the separate areas to determine if there is any correlation between them is needed. Some uranium ores in South Texas show disequilibrium between gamma radioactivity of the non...

Fishman, Paul Harold

2012-06-07

325

Uranium stripping from tertiary amine loaded solution by ammonium sulfate  

Microsoft Academic Search

Uranium in sulfuric acid medium is selectively extracted by tertiary amine. Uranium stripping from the loaded solvent (tertiary amine) can be carried out by many salt and acid solutions. The stripping agent choice depends on several factors, such as organic composition and economic viability. In the present work, the uranium stripping by (NH4)2SO4 was investigated in order to substitute the

Carlos A. Morais; Luiz A. Gomiero

2005-01-01

326

The Navajo Uranium Mining Experience, 2003-1952  

NSDL National Science Digital Library

This bibliography, compiled by the Southwest Research and Information Center, contains resources related to Navajo uranium issues and communities affected by uranium mining impacts since the mid-1970s. Entries were selected for their relevancy to Navajo community concerns, Navajo Nation policies, and health and environmental effects of uranium development on Navajo lands. Topics for resources include articles, books, policy statements, reports, presentations, testimony, and published medical, scientific and sociological literature.

Shuey, Chris; Center, Southwest R.

327

Rapid removal of uranium from aqueous solutions using magnetic Fe3O4@SiO2 composite particles.  

PubMed

Rapid removal of U(VI) from aqueous solutions was investigated using magnetic Fe(3)O(4)@SiO(2) composite particles as the novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, shaking time and initial U(VI) concentrations on uranium sorption efficiency as well as the desorbing of U(VI). The sorption of uranium on Fe(3)O(4)@SiO(2) composite particles was pH-dependent, and the optimal pH was 6.0. In kinetics studies, the sorption equilibrium can be reached within 180 min, and the experimental data were well fitted by the pseudo-second-order model, and the equilibrium sorption capacities calculated by the model were almost the same as those determined by experiments. The Langmuir sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 20-200 mg/L. The maximum uranium sorption capacity onto magnetic Fe(3)O(4)@SiO(2) composite particles was estimated to be about 52 mg/g at 25 °C. The highest values of uranium desorption (98%) was achieved using 0.01 M HCl as the desorbing agent. Fe(3)O(4)@SiO(2) composite particles showed a good selectivity for uranium from aqueous solution with other interfering cation ions. Present study suggested that magnetic Fe(3)O(4)@SiO(2) composite particles can be used as a potential adsorbent for sorption uranium and also provided a simple, fast separation method for removal of heavy metal ion from aqueous solution. PMID:22304999

Fan, Fang-Li; Qin, Zhi; Bai, Jing; Rong, Wei-Dong; Fan, Fu-You; Tian, Wei; Wu, Xiao-Lei; Wang, Yang; Zhao, Liang

2012-04-01

328

The selective conversion of glutamic acid in amino acid mixtures using glutamate decarboxylase--a means of separating amino acids for synthesizing biobased chemicals.  

PubMed

Amino acids (AAs) derived from hydrolysis of protein rest streams are interesting feedstocks for the chemical industry due to their functionality. However, separation of AAs is required before they can be used for further applications. Electrodialysis may be applied to separate AAs, but its efficiency is limited when separating AAs with similar isoelectric points. To aid the separation, specific conversion of an AA to a useful product with different charge behavior to the remaining compounds is desired. Here the separation of L-aspartic acid (Asp) and L-glutamic acid (Glu) was studied. L-Glutamate ?-decarboxylase (GAD, Type I, EC 4.1.1.15) was applied to specifically convert Glu into ?-aminobutyric acid (GABA). GABA has a different charge behavior from Asp therefore allowing a potential separation by electrodialysis. Competitive inhibition and reduced operational stability caused by Asp could be eliminated by maintaining a sufficiently high concentration of Glu. Immobilization of GAD does not reduce the enzyme's initial activity. However, the operational stability was slightly reduced. An initial study on the reaction operating in a continuous mode was performed using a column reactor packed with immobilized GAD. As the reaction mixture was only passed once through the reactor, the conversion of Glu was lower than expected. To complete the conversion of Glu, the stream containing Asp and unreacted Glu might be recirculated back to the reactor after GABA has been removed. Overall, the reaction by GAD is specific to Glu and can be applied to aid the electrodialysis separation of Asp and Glu. PMID:24616376

Teng, Yinglai; Scott, Elinor L; Sanders, Johan P M

2014-01-01

329

Performance of a uranium liquid argon calorimeter  

SciTech Connect

We present results on the performance of a uranium and liquid argon calorimeter in the NW test beam at Fermilab. We describe the calorimeter, and discuss its performance with electrons, pions and muons from 10 GeV to 150 GeV. The performance perameters measured include response, linearity, resolution, compensation, and e/..pi.. separation.

Tuts, P.M.

1986-01-01

330

Chiral Separations  

NASA Astrophysics Data System (ADS)

The main goal of this review is to provide a brief overview of chiral separations to researchers who are versed in the area of analytical separations but unfamiliar with chiral separations. To researchers who are not familiar with this area, there is currently a bewildering array of commercially available chiral columns, chiral derivatizing reagents, and chiral selectors for approaches that span the range of analytical separation platforms (e.g., high-performance liquid chromatography, gas chromatography, supercritical-fluid chromatography, and capillary electrophoresis). This review begins with a brief discussion of chirality before examining the general strategies and commonalities among all of the chiral separation techniques. Rather than exhaustively listing all the chiral selectors and applications, this review highlights significant issues and differences between chiral and achiral separations, providing salient examples from specific classes of chiral selectors where appropriate.

Stalcup, A. M.

2010-07-01

331

Plant-uptake of uranium: Hydroponic and soil system studies  

USGS Publications Warehouse

Limited information is available on screening and selection of terrestrial plants for uptake and translocation of uranium from soil. This article evaluates the removal of uranium from water and soil by selected plants, comparing plant performance in hydroponic systems with that in two soil systems (a sandy-loam soil and an organic-rich soil). Plants selected for this study were Sunflower (Helianthus giganteus), Spring Vetch (Vicia sativa), Hairy Vetch (Vicia villosa), Juniper (Juniperus monosperma), Indian Mustard (Brassica juncea), and Bush Bean (Phaseolus nanus). Plant performance was evaluated both in terms of the percent uranium extracted from the three systems, as well as the biological absorption coefficient (BAC) that normalized uranium uptake to plant biomass. Study results indicate that uranium extraction efficiency decreased sharply across hydroponic, sandy and organic soil systems, indicating that soil organic matter sequestered uranium, rendering it largely unavailable for plant uptake. These results indicate that site-specific soils must be used to screen plants for uranium extraction capability; plant behavior in hydroponic systems does not correlate well with that in soil systems. One plant species, Juniper, exhibited consistent uranium extraction efficiencies and BACs in both sandy and organic soils, suggesting unique uranium extraction capabilities.

Ramaswami, A.; Carr, P.; Burkhardt, M.

2001-01-01

332

DYNAMIC PROPERTIES OF SHOCK LOADED THIN URANIUM FOILS  

SciTech Connect

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium spall targets, from deformation to complete spall or separation at the higher velocities. Dynamic measurements of the uranium target free surface velocities were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles were similar for the two types of uranium, but spall strengths (estimated from the magnitude of the pull-back signal) are higher for the high-purity cast uranium. Velocity profiles and microstructural evidence of spall from the sectioned uranium targets are presented.

Robbins, D. L. (David L.); Kelly, A. M. (Anna Marie); Alexander, D. J. (David J.); Hanrahan, R. J. (Robert J.); Snow, R. C. (Ronny C.); Gehr, R. J. (Russell J.); Rupp, Ted Dean,; Sheffield, S. A. (Stephen A.); Stahl, D. B. (David B.)

2001-01-01

333

Dynamic Properties of Shock Loaded Thin Uranium Foils  

NASA Astrophysics Data System (ADS)

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium targets, from deformation to complete spall or separation at the higher velocities. Dynamic measurements of the uranium target free surface velocities were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles were similar for the two types of uranium, but spall strengths (estimated from the magnitude of the pull-back signal) are higher for the high-purity cast uranium. Velocity profiles and microstructural evidence of spall from the sectioned uranium targets are presented.

Robbins, David L.; Kelly, Ann M.; Alexander, David J.; Hanrahan, Robert J.; Snow, Ronny C.; Gehr, Russell J.; Rupp, Ted D.; Sheffield, Stephen A.; Stahl, David B.

2002-07-01

334

Water separator  

NASA Technical Reports Server (NTRS)

An apparatus for separating liquids from gases or gaseous fluids is described. Features of the apparatus include: (1) the collection and removal of the moisture in the fluid is not dependent upon, or affected by gravity; (2) all the collected water is cyclically drained from the apparatus irrespective of the attitude of the separator; and (3) a fluid actuator is utilized to remove the collected water from the separator.

Dunn, W. F.; Austin, I. G. (inventors)

1964-01-01

335

Separation Anxiety  

NSDL National Science Digital Library

In this activity, learners discover the primary physical properties used to separate pure substances from mixtures. Learners use test tubes, beakers, magnets, and other tools to separate a mixture of sand, iron filings, salt, popcorn kernels, and poppyseeds. This activity introduces learners to the basic properties of size, magnetism, density and solubility while emphasizing that chemistry involves separating out substances either to understand what they are or to use the pure components to create new substances.

Yu, Julie

2007-01-01

336

Separating Mixtures  

NSDL National Science Digital Library

Students learn how to classify materials as mixtures, elements or compounds and identify the properties of each type. The concept of separation of mixtures is also introduced since nearly every element or compound is found naturally in an impure state such as a mixture of two or more substances, and it is common that chemical engineers use separation techniques to separate mixtures into their individual components. For example, the separation of crude oil into purified hydrocarbons such as natural gas, gasoline, diesel, jet fuel and/or lubricants.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

337

Characterization of streamflow, water quality, and instantaneous dissolved solids, selenium, and uranium loads in selected reaches of the Arkansas River, southeastern Colorado, 2009-2010  

USGS Publications Warehouse

As a result of continued water-quality concerns in the Arkansas River, including metal contamination from historical mining practices, potential effects associated with storage and movement of water, point- and nonpoint-source contamination, population growth, storm-water flows, and future changes in land and water use, the Arkansas River Basin Regional Resource Planning Group (RRPG) developed a strategy to address these issues. As such, a cooperative strategic approach to address the multiple water-quality concerns within selected reaches of the Arkansas River was developed to (1) identify stream reaches where stream-aquifer interactions have a pronounced effect on water quality and (or) where reactive transport, and physical and (or) chemical alteration of flow during conveyance, is occurring, (2) quantify loading from point sources, and (3) determine source areas and mass loading for selected constituents. (To see the complete abstract, open Report PDF.)

Ivahnenko, Tamara; Ortiz, Roderick F.; Stogner, Robert W., Sr.

2013-01-01

338

Inorganic separator technology program  

NASA Technical Reports Server (NTRS)

Testing and failure analyses of silver zinc cells with largely inorganic separators were performed. The results showed that the wet stand and cycle life objective of the silver-zinc cell development program were essentially accomplished and led to recommendations for cell composition, design, and operation that should yield further improvement in wet and cycle life. A series of advanced inorganic materials was successfully developed and formulated into rigid and semiflexible separator samples. Suitable screening tests for evaluation of largely inorganic separators were selected and modified for application to the separator materials. The results showed that many of these formulations are potentially superior to previously used materials and permitted selection of three promising materials for further evaluation in silver-zinc cells.

Smatko, J. S.; Weaver, R. D.; Kalhammer, F. R.

1973-01-01

339

An equilibrium model for ligand-modified micellar-enhanced ultrafiltration, selective separation of metal ions using iminoacetic substituted polyamines and a theoretical model for the titration behavior of polyamines  

SciTech Connect

This thesis consists of three chapters. Chapter 1, An equilibrium model for ligand-modified micellar-enhanced ultrafiltration, describes a theoretical model and experimental investigations which used the semi-equilibrium-dialysis method with N-n-dodecyl iminodiacetic acid as the ligand. In Chapter 2, Selective separation of metal ions using iminoacetic substituted polyamines, polyamines with a substituted ligand group are synthesized and used in investigating selective separation of copper ions from aqueous solution. In Chapter 3, A theoretical model for the titration behavior of polyamines, a novel approach to explain the titration behavior of polymeric amines based on the binding behavior of counterions is described. The application of this study is to the investigation of inexpensive and efficient methods of industrial waste water treatment.

Dharmawardana, U.R.

1992-12-31

340

Layered metal sulfides capture uranium from seawater.  

PubMed

Uranium is the main source for nuclear energy but also one of the most toxic heavy metals. The current methods for uranium removal from water present limitations, such as narrow pH operating range, limited tolerance to high salt concentrations, or/and high cost. We show here that a layered sulfide ion exchanger K(2)MnSn(2)S(6) (KMS-1) overcomes these limitations and is exceptionally capable in selectively and rapidly sequestering high (ppm) as well as trace (ppb) quantities of UO(2)(2+) under a variety of conditions, including seawater. KMS-1 can efficiently absorb the naturally occurring U traces in seawater samples. The results presented here reveal the exceptional potential of sulfide-based ion-exchangers for remediating of uranium-containing wastes and groundwater and for extracting uranium from the sea. PMID:23009164

Manos, Manolis J; Kanatzidis, Mercouri G

2012-10-01

341

The effects of solid rocket motor effluents on selected surfaces and solid particle size, distribution, and composition for simulated shuttle booster separation motors  

NASA Technical Reports Server (NTRS)

A series of three tests was conducted using solid rocket propellants to determine the effects a solid rocket plume would have on thermal protective surfaces (TPS). The surfaces tested were those which are baselined for the shuttle vehicle. The propellants used were to simulate the separation solid rocket motors (SSRM) that separate the solid rocket boosters (SRB) from the shuttle launch vehicle. Data cover: (1) the optical effects of the plume environment on spacecraft related surfaces, and (2) the solid particle size, distribution, and composition at TPS sample locations.

Jex, D. W.; Linton, R. C.; Russell, W. M.; Trenkle, J. J.; Wilkes, D. R.

1976-01-01

342

Selective Separation of Rare Earth Metals by Solvent Extraction in the Presence of New Hydrophilic Chelating Polymers Functionalized with Ethylenediaminetetraacetic Acid. I. Development of New Hydrophilic Chelating Polymers and Their Adsorption Properties for Rare Earth Metals  

Microsoft Academic Search

New hydrophilic chelating polymers were synthesized by introducing ethylene-diaminetetraacetic acid (EDTA) onto water-soluble polyallylamine. The selective separation of rare earth metals by solvent extraction including these chelating polymers in the aqueous phase is the goal of this work. The polymers were characterized by IR analysis, elemental analysis, gel permeation chromatography (GPC) measurement, and pH titration. Two kinds of polymers with

Hideto Matsuyama; Yoshikazu Miyamoto; Masaaki Teramoto; Masahiro Goto; Fumiyuki Nakashio

1996-01-01

343

Interplay of Metalloligand and Organic Ligand to Tune Micropores within Isostructural Mixed-Metal Organic Frameworks (M MOFs) for Their Highly Selective Separation of Chiral and Achiral Small Molecules  

SciTech Connect

Four porous isostructural mixed-metal-organic frameworks (M'MOFs) have been synthesized and structurally characterized. The pores within these M'MOFs are systematically tuned by the interplay of both the metalloligands and organic ligands which have enabled us not only to direct their highly selective separation of chiral alcohols 1-phenylethanol (PEA), 2-butanol (BUT), and 2-pentanol (2-PEN) with the highest ee up to 82.4% but also to lead highly selective separation of achiral C{sub 2}H{sub 2}/C{sub 2}H{sub 4} separation. The potential application of these M'MOFs for the fixed bed pressure swing adsorption (PSA) separation of C{sub 2}H{sub 2}/C{sub 2}H{sub 4} has been further examined and compared by the transient breakthrough simulations in which the purity requirement of 40 ppm in the outlet gas can be readily fulfilled by the fixed bed M'MOF-4a adsorber at ambient conditions.

Madhab, Das [University of Texas at San Antonio (UTSA); He, Yabing [University of Texas at San Antonio (UTSA); Kim, Jaheon [Soongsil University, Korea; Guo, Qunsheng [University of Texas at San Antonio (UTSA); Zhao, Cong-Gui [University of Texas at San Antonio (UTSA); Hong, Kunlun [ORNL; Xiang, Sheng-Chang [University of Texas at San Antonio (UTSA); Zhang, Zhangjing [University of Texas at San Antonio (UTSA); Thomas, K Mark [University of Newcastle upon Tyne; Krishna, Rajamani [Universitate Amsterdam; Chen, Banglin [University of Texas at San Antonio (UTSA)

2012-01-01

344

Tetravalent uranium in calcite  

PubMed

X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducing conditions. This result validates uranium-series dating methods (including uranium/lead dating) for ancient calcite and shows that calcite provides a sink for uranium in deep groundwater aquifers and anoxic lacustrine and marine basins. PMID:9703507

Sturchio; Antonio; Soderholm; Sutton; Brannon

1998-08-14

345

Tetravalent uranium in calcite.  

SciTech Connect

X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducing conditions. This result validates uranium-series dating methods (including uranium/lead dating) for ancient calcite and shows that calcite provides a sink for uranium in deep groundwater aquifers and anoxic lacustrine and marine basins.

Sturchio, N. C.; Antonio, M. R.; Soderholm, L.; Sutton, S. R.; Brannon, J. C.; Univ. of Chicago; Washington Univ.

1998-08-14

346

Thermodynamic properties of selected uranium compounds and aqueous species at 298.15 K and 1 bar and at higher temperatures; preliminary models for the origin of coffinite deposits  

USGS Publications Warehouse

Thermodynamic values for 110 uranium-bearing phases and 28 aqueous uranium solution species (298.15 K and l bar) are tabulated based upon evaluated experimental data (largely from calorimetric experiments) and estimated values. Molar volume data are given for most of the solid phases. Thermodynamic values for 16 uranium-bearing phases are presented for higher temperatures in the form of and as a supplement to U.S. Geological Survey Bulletin 1452 (Robie et al., 1979). The internal consistency of the thermodynamic values reported herein is dependent upon the reliability of the experimental results for several uranium phases that have been used as secondary calorimetric reference phases. The data for the reference phases and for those phases evaluated with respect to the secondary reference phases are discussed. A preliminary model for coffinite formation has been proposed together with an estimate of the free energy of formation of coffinite. Free energy values are estimated for several other uranium-bearing silicate phases that have been reported as secondary uranium phases associated with uranium ore deposits and that could be expected to develop wherever uranium is leached by groundwaters.

Hemingway, B.S.

1982-01-01

347

Separation and Analytical Chemistry of the Actinides  

SciTech Connect

The determination of low levels of actinides from water samples and aqueous waste streams involves a lengthy and complicated process which is characterized by low recoveries and poor precision. The objective of this work was to evaluate the use of a Photon Electron Rejecting Alpha Liquid Scintillation Spectrometer (PERALS{reg_sign}), in combination with extractive scintillators, for the detection of actinides. The results of the application of this method to aqueous samples containing uranium, thorium, plutonium, and americium, both individually and in mixtures showed promising results. Using a commercially available extractant, ALPHAEX{reg_sign}, recoveries of plutonium and americium were > 98.4% in individual samples and in mixtures with activities ranging from 6 pci to 500 pci. The separation of these two elements was accomplished by selective extraction after adjusting the acidity of the aqueous sample. The application of this technique to a raw waste sample showed reasonable recoveries when combined with classical anion exchange separation techniques. Efforts to develop an extractive scintillator using a recently synthesized tetradentate extractant were only moderately successful since solubility problems limit the extractant's efficiency in the scintillator. The application of a curve fitting program, PEAKFIT{reg_sign}, to spectra obtained using the PERALS{reg_sign} spectrometer provided useful isotropic information.

Ensor, D.D.

1998-06-30

348

Battery separators  

Microsoft Academic Search

A description is given of a synthetic pulp separator for a lead acid battery, the separator having two or more plies and a ribbed profile the surface adapted to face the positive having a higher content of synthetic pulp than the other surface.

G. A. Clegg; E. J. Pearson

1981-01-01

349

Battery separators  

SciTech Connect

A description is given of a synthetic pulp separator for a lead acid battery, the separator having two or more plies and a ribbed profile the surface adapted to face the positive having a higher content of synthetic pulp than the other surface.

Clegg, G.A.; Pearson, E.J.

1981-01-13

350

Lead isotopes as seepage indicators around a uranium tailings dam  

Microsoft Academic Search

Lead isotope ratios and lead concentrations have been measured in water from 26 bores around the Ranger uranium tailings dam, Northern Territory, Australia, and from the dam itself to determine possible migration of lead derived from the radioactive decay of uranium. Lead isotope compositions have also been measured for the particulates retained on selected filters. The concentration of lead in

Brian L. Gulson; Karen J. Mizon; Michael J. Korsch; Barry N. Noller

1989-01-01

351

MICRONUCLEI IN EPITHELIAL CELLS FROM SPUTUM OF URANIUM WORKERS  

EPA Science Inventory

The exfoliated-cell micronucleus (MN) assay was used to assess cytogenetic effects of exposure to radon progeny and cigarette smoke among 99 Colorado plateau uranium workers. ubjects were selected at random from employees in underground and open-pit uranium mines, ore mills, labo...

352

Amidoxime-grafted multiwalled carbon nanotubes by plasma techniques for efficient removal of uranium(VI)  

NASA Astrophysics Data System (ADS)

A novel solid-phase extractant, amidoxime-grafted multiwalled carbon nanotubes (AO-g-MWCNTs), has been synthesized using plasma techniques to selectively separate uranium from nuclear industrial effluents. The adsorbent was characterized by Fourier transform infrared spectra (FT-IR), elemental analysis, Raman, scanning electron microscopy (SEM), and thermal gravity analysis (TGA). Sorption behaviors of uranium(VI) on AO-g-MWCNTs were investigated by varying pH, contact time, initial uranium concentration, and temperature. An optimum sorption capacity of 145 mg g-1 (0.61 mmol g-1) for U(VI) was obtained at pH 4.5. X-ray photoelectron spectroscopy (XPS) has been used to explore the sorption mechanism of U(VI) on AO-g-MWCNTs. Furthermore, AO-g-MWCNTs could selectively adsorb U(VI) in aqueous solution containing co-existing ions (Mn2+, Co2+, Ni2+, Zn2+, Sr2+, Ba2+ and Cs+). This study shows that AO-g-MWCNTs are potential adsorbent for effective removal of U(VI) from aqueous solution.

Wang, Yun; Gu, Zexing; Yang, Jijun; Liao, Jiali; Yang, Yuanyou; Liu, Ning; Tang, Jun

2014-11-01

353

Depleted-uranium recovery from and cleaning of target sands  

SciTech Connect

This patent describes a method of removing uranium and its oxidation products from target sands and consists of: (a) providing a container means which can be heated; (b) adding uranium-containing target sands to the container; (c) adding a salt mixture comprising at least 70 weight percent of a salt selected from the group consisting of nitrates of magnesium, calcium, potassium, sodium, and lithium to the container; (d) heating the target sands and the salt mixture together to fuse the salt to convert the uranium to uranium oxidation products; (e) adding water to dissolve the salt component into aqueous solution and removing the aqueous solution; (f) adding nitric acid to dissolve the uranium oxidation products into aqueous nitric acid solution; and (g) rinsing the target sands with water washing out the dissolved uranium oxidation products.

Elliott, G.R.B.

1986-02-04

354

Selective separation of nickel and cadmium from sulfate solutions of spent nickel-cadmium batteries using mixtures of D2EHPA and Cyanex 302  

NASA Astrophysics Data System (ADS)

The synergistic effect of Cyanex 302 on solvent extraction of nickel and cadmium from sulfate solution with D2EHPA diluted in kerosene has been investigated with the aim of increasing separation efficiency. Experiments are carried out using the sole D2EHPA and also D2EHPA-Cyanex 302 mixtures in different ratios. As a result, satisfactory separation has been found with a Cyanex 302 to D2EHPA ratio of 0.1 M:0.5 M. The extraction equilibrium constants, enthalpy change, and entropy change of the cadmium extraction are also determined. The stoichiometric coefficient of cadmium for the sole D2EHPA and three different D2EHPA to Cyanex 302 ratios has been determined by applying the slope analysis method. The experimental data of cadmium extraction have been employed to model the distribution coefficient of cadmium by multiple linear regression.

Babakhani, Ataollah; Rashchi, Fereshteh; Zakeri, Alireza; Vahidi, Ehsan

2014-02-01

355

Stationary phases in the screening of drug\\/impurity profiles and in their separation method development: Identification of columns with different and similar selectivities  

Microsoft Academic Search

The classification or characterization of stationary phases based on chromatographic parameters, in general, requires different test solutes\\/mixtures and several mobile phases. To simplify the classification\\/characterization of reversed-phase liquid chromatographic columns, to be used in separating drug\\/impurity profiles, a new test procedure was proposed. It consists of injecting two mixtures of relatively similar active substances applying a standard gradient. The aim

E. Van Gyseghem; M. Jimidar; R. Sneyers; M. De Smet; E. Verhoeven; Y. Vander Heyden

2006-01-01

356

Cationic and anionic polymeric additives for wall deactivation and selectivity control in the capillary electrophoretic separation of proteins in food samples  

Microsoft Academic Search

Both cationic and anionic polymeric additives were used for the capillary electrophoretic separation of proteins in food samples. The cationic polyelectrolyte polydiallyldimethylammonium chloride was more effective in minimizing protein–wall interactions at pH 3 than at pH 7, presumably due to greater repulsion between the adsorbed polymer and proteins. Improved resolution was observed in the presence of the co-additive sodium octanesulphonate,

Costas Stathakis; Edgar A. Arriaga; Darren F. Lewis; Norman J. Dovichi

1998-01-01

357

Stereoisomers Separation  

NASA Astrophysics Data System (ADS)

The use of capillary electrophoresis for enantiomer separation and optical purity determination is presented. The contents start with basic information about the nature of stereoizomers and the mechanism of enantioseparation using capillary electrophoresis techniques. The molecules to be separated show identical chemical structure and electrochemical behavior. Therefore, the chiral recognition of enantiomers is possible only by bonding to chiral selector and the separation based on very small differences in complexation energies of diastereomer complexes formed. This method is useful for this purpose due to the fact that different compounds can be used as chiral selectors. The mostly used chiral selectors like cyclodextrins, crown ethers, chiral surfactants, macrocyclic antibiotics, transition metal complexes, natural, and synthetic polymers and their application for this purpose is also discussed. Finally, examples of practical applications of electromigration techniques for enantiomers separation and determination are presented.

Wieczorek, Piotr

358

Fault Separation  

NSDL National Science Digital Library

Students use gestures to explore the relationship between fault slip direction and fault separation by varying the geometry of faulted layers, slip direction, and the perspective from which these are viewed.

Ormand, Carol

359

Battery separator  

Microsoft Academic Search

A battery separator and a method of forming the same is described. The separator has good electrical conductivity and a high degree of inhibition to dendrite formation, and is in the form of a thin sheet formed from a substantially uniform mixture of a thermoplastic rubber and a filler in a volume ratio of from about 1:0.15 to 1:0.6. The

R. A. Balouskus; S. C. Feinberg; J. T. Lundquist; C. B. Lundsager

1980-01-01

360

Uranium hexafluoride public risk  

SciTech Connect

The limiting value for uranium toxicity in a human being should be based on the concentration of uranium (U) in the kidneys. The threshold for nephrotoxicity appears to lie very near 3 {mu}g U per gram kidney tissue. There does not appear to be strong scientific support for any other improved estimate, either higher or lower than this, of the threshold for uranium nephrotoxicity in a human being. The value 3 {mu}g U per gram kidney is the concentration that results from a single intake of about 30 mg soluble uranium by inhalation (assuming the metabolism of a standard person). The concentration of uranium continues to increase in the kidneys after long-term, continuous (or chronic) exposure. After chronic intakes of soluble uranium by workers at the rate of 10 mg U per week, the concentration of uranium in the kidneys approaches and may even exceed the nephrotoxic limit of 3 {mu}g U per gram kidney tissue. Precise values of the kidney concentration depend on the biokinetic model and model parameters assumed for such a calculation. Since it is possible for the concentration of uranium in the kidneys to exceed 3 {mu}g per gram tissue at an intake rate of 10 mg U per week over long periods of time, we believe that the kidneys are protected from injury when intakes of soluble uranium at the rate of 10 mg U per week do not continue for more than two consecutive weeks. For long-term, continuous occupational exposure to low-level, soluble uranium, we recommend a reduced weekly intake limit of 5 mg uranium to prevent nephrotoxicity in workers. Our analysis shows that the nephrotoxic limit of 3 {mu}g U per gram kidney tissues is not exceeded after long-term, continuous uranium intake at the intake rate of 5 mg soluble uranium per week.

Fisher, D.R.; Hui, T.E.; Yurconic, M.; Johnson, J.R.

1994-08-01

361

Synthesis of Uranium Trichloride for the Pyrometallurgical Processing of Used Nuclear Fuel  

SciTech Connect

The pyroprocessing of used nuclear fuel via electrorefining requires the continued addition of uranium trichloride to sustain operations. Uranium trichloride is utilized as an oxidant in the system to allow separation of uranium metal from the minor actinides and fission products. The inventory of uranium trichloride had diminished to a point that production was necessary to continue electrorefiner operations. Following initial experimentation, cupric chloride was chosen as a reactant with uranium metal to synthesize uranium trichloride. Despite the variability in equipment and charge characteristics, uranium trichloride was produced in sufficient quantities to maintain operations in the electrorefiner. The results and conclusions from several experiments are presented along with a set of optimized operating conditions for the synthesis of uranium trichloride.

B.R. Westphal; J.C. Price; R.D. Mariani

2011-11-01

362

Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Falls City, Texas. Remedial action selection report, attachment 2, geology report; attachment 3, groundwater hydrology report; and attachment 4, water resources protection strategy. Final report  

SciTech Connect

The uranium processing site near Falls City, Texas, was one of 24 inactive uranium mill sites designated to be remediated by the U.S. Department of Energy (DOE) under Title I of the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). The UMTRCA requires that the U.S. Nuclear Regulatory Commission (NRC) concur with the DOE`s remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the U.S. Environmental Protection Agency (EPA). The RAP, which includes this summary remedial action selection report (RAS), serves a two-fold purpose. First, it describes the activities proposed by the DOE to accomplish long-term stabilization and control of the residual radioactive materials at the inactive uranium processing site near Falls City, Texas. Second, this document and the remainder of the RAP, upon concurrence and execution by the DOE, the State of Texas, and the NRC, becomes Appendix B of the Cooperative Agreement between the DOE and the State of Texas.

NONE

1992-09-01

363

31 CFR 540.317 - Uranium feed; natural uranium feed.  

... 3 2014-07-01 2014-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2014-07-01

364

Separation of C70 over C60 and selective extraction and resolution of higher fullerenes by syndiotactic helical poly(methyl methacrylate).  

PubMed

A one-handed helical polymer, syndiotactic poly(methyl methacrylate) (st-PMMA), recognizes the size and chirality of higher fullerenes through an induced-fit mechanism and can selectively extract enantiomers of the higher fullerenes, such as C(76), C(80), C(84), C(86), C(88,) C(90), C(92), C(94), and C(96). This discovery will generate a practical and valuable method for selectively extracting the elusive higher fullerenes and their enantiomers and opens the way to developing novel carbon cage materials with optical activities. PMID:20715869

Kawauchi, Takehiro; Kitaura, Atsushi; Kawauchi, Mariko; Takeichi, Tsutomu; Kumaki, Jiro; Iida, Hiroki; Yashima, Eiji

2010-09-01

365

Accumulation of uranium by immobilized persimmon tannin  

SciTech Connect

We have discovered that the extracted juice of unripe astringent persimmon fruit, designated as kakishibu or shibuol, has an extremely high affinity for uranium. To develop efficient adsorbents for uranium, we tried to immobilize kakishibu (persimmon tannin) with various aldehydes and mineral acids. Persimmon tannin immobilized with glutaraldehyde can accumulate 1.71 g (14 mEq U) of uranium per gram of the adsorbent. The uranium accumulating capacity of this adsorbent is several times greater than that of commercially available chelating resins (2-3 mEq/g). Immobilized persimmon tannin has the most favorable features for uranium recovery; high selective adsorption ability, rapid adsorption rate, and applicability in both column and batch systems. The uranium retained on immobilized persimmon tannin can be quantitatively and easily eluted with a very dilute acid, and the adsorbent can thus be easily recycled in the adsorption-desorption process. Immobilized persimmon tannin also has a high affinity for thorium. 23 refs., 13 figs., 7 tabs.

Sakaguchi, Takashi; Nakajima, Akira (Miyazaki Medical College (Japan))

1994-01-01

366

Microbial transformation of uranium in wastes  

SciTech Connect

Contamination of soils, water, and sediments by radionuclides and toxic metals from the disposal of uranium processing wastes is a major national concern. Although much is known about the physico- chemical aspects of U, we have little information on the effects of aerobic and anaerobic microbial activities on the mobilization or immobilization of U and other toxic metals in mixed wastes. In order to understand the mechanisms of microbial transformations of uranium, we examined a contaminated pond sediment and a sludge sample from the uranium processing facility at Y-12 Plant, Oak Ridge, TN. The uranium concentration in the sediment and sludge samples was 923 and 3080 ug/g dry wt, respectively. In addition to U, the sediment and sludge samples contained high levels of toxic metals such as Cd, Cr, Cu, Hg, Pb, Ni, and Zn. The association of uranium with the various mineral fractions of the sediment and sludge was determined by selective chemical extraction techniques. Uranium was associated to varying degrees with the exchangeable carbonate, iron oxide, organic, and inert fractions in both samples. Initial results in samples amended with carbon and nitrogen indicate immobilization of U due to enhanced indigenous microbial activity under anaerobic conditions. 23 refs., 4 figs., 5 tabs.

Francis, A.J.; Dodge, C.J.; Gillow, J.B.; Cline, J.E. (Brookhaven National Lab., Upton, NY (USA); Oak Ridge Y-12 Plant, TN (USA))

1989-01-01

367

Fine tuning of the PCDTBT-OR:PC71BM blend nanoscale phase separation via selective solvent annealing toward high-performance polymer photovoltaics.  

PubMed

Solution-processable polymer solar cells show great promise for providing a cost-effective route to create lightweight and flexible solar energy conversion devices. The photoactive layer comprising the conjugated polymer donor and fullerene derivative acceptor must be optimized to form bicontinuous nanoscale phase separation in order for efficient exciton dissociation and charge collection due to the short exciton diffusion length of organic semiconductors. The donor polymer poly[9-(heptadecan-9-yl)-9H-carbazole- 2,7-diyl-alt-(5,6-bis(hexyloxy)-4,7-di(thiophen-2- yl)benzo[c][1,2,5]thiadiazole)-5,5-diyl] (PCDTBT-OR) has a deeper highest occupied molecular orbital level compared to its counterpart PCDTBT, and shows promise in increasing the open-circuit voltage and power conversion efficiency (PCE) of polymer solar cells. The phase separation evolution of the PCDTBT-OR:PC71BM blend with various weight ratios under tetrahydrofuran (THF) vapor annealing and its influence on the photovoltaic performance is investigated in detail. It is found that THF vapor annealing can promote the acceptor PC71BM aggregation from the donor PCDTBT-OR matrix to form nanoscale donor/acceptor phase separation for efficient exciton dissociation and charge collection depending on the donor/acceptor weight ratio and the annealing time. The THF vapor-annealed PCDTBT-OR:PC71BM solar cells exhibit remarkable enhancement, with a PCE of 7.01% compared to 3.25% of the as-cast solar cells with the same active layer thickness. This work provides a general methodology to construct nano-interpenetrating networks for homogeneous polymer/fullerene blends and is potentially applicable to the roll-to-roll manufacturing of polymer solar cells. PMID:24196394

Meng, Bin; Fang, Gang; Fu, Yingying; Xie, Zhiyuan; Wang, Lixiang

2013-12-01

368

Fine tuning of the PCDTBT-OR:PC71BM blend nanoscale phase separation via selective solvent annealing toward high-performance polymer photovoltaics  

NASA Astrophysics Data System (ADS)

Solution-processable polymer solar cells show great promise for providing a cost-effective route to create lightweight and flexible solar energy conversion devices. The photoactive layer comprising the conjugated polymer donor and fullerene derivative acceptor must be optimized to form bicontinuous nanoscale phase separation in order for efficient exciton dissociation and charge collection due to the short exciton diffusion length of organic semiconductors. The donor polymer poly[9-(heptadecan-9-yl)-9H-carbazole- 2,7-diyl-alt-(5,6-bis(hexyloxy)-4,7-di(thiophen-2- yl)benzo[c][1,2,5]thiadiazole)-5,5-diyl] (PCDTBT-OR) has a deeper highest occupied molecular orbital level compared to its counterpart PCDTBT, and shows promise in increasing the open-circuit voltage and power conversion efficiency (PCE) of polymer solar cells. The phase separation evolution of the PCDTBT-OR:PC71BM blend with various weight ratios under tetrahydrofuran (THF) vapor annealing and its influence on the photovoltaic performance is investigated in detail. It is found that THF vapor annealing can promote the acceptor PC71BM aggregation from the donor PCDTBT-OR matrix to form nanoscale donor/acceptor phase separation for efficient exciton dissociation and charge collection depending on the donor/acceptor weight ratio and the annealing time. The THF vapor-annealed PCDTBT-OR:PC71BM solar cells exhibit remarkable enhancement, with a PCE of 7.01% compared to 3.25% of the as-cast solar cells with the same active layer thickness. This work provides a general methodology to construct nano-interpenetrating networks for homogeneous polymer/fullerene blends and is potentially applicable to the roll-to-roll manufacturing of polymer solar cells.

Meng, Bin; Fang, Gang; Fu, Yingying; Xie, Zhiyuan; Wang, Lixiang

2013-12-01

369

Politics of Uranium  

SciTech Connect

Uranium is the most political of all the elements, the material for the production of both the large amounts of electricity and the most destructive weapons in the world. The problems that its dual potential creates are only now beginning to become evident. Author Norman Moss looks at this situation and sheds light on many of the questions that emerge. The nuclear issue always comes back to how much uranium there is, what can be done with it, and which countries have it. Starting with a concise history of uranium and explaining its technology in terms the nonspecialist can understand, The Politics of Uranium considers the political issues that technical arguments obscure. It tells the little-known story of the international uranium cartel, explains the entanglements of governments with the uranium trade, and describes the consequences of wrong decisions and blunders-especially the problems of nuclear waste. It also examines the intellectual and emotional roots of the anti-nuclear movement.

Moss, N.

1982-01-01

370

Selective extraction, separation and speciation of iron in different samples using 4-acetyl-5-methyl-1-phenyl-1 H-pyrazole-3-carboxylic acid  

Microsoft Academic Search

A method for speciation, preconcentration and separation of Fe(II) and Fe(III) in different matrices was developed using solvent extraction and flame atomic absorption spectrometry. 4-Acetyl-5-methyl-1-phenyl-1H-pyrazole-3-carboxylic acid (AMPC) was used as a new complexing reagent for Fe(III). The Fe(III)–AMPC complex was extracted into methyl isobutyl ketone (MIBK) phase in the pH range 1.0–2.5, and Fe(II) ion remained in aqueous phase at

?erife Saçmac?; ?enol Kartal

2008-01-01

371

Uranium geochemistry, mineralogy, geology, exploration and resources  

Microsoft Academic Search

This book comprises papers on the following topics: history of radioactivity; uranium in mantle processes; transport and deposition of uranium in hydrothermal systems at temperatures up to 300°C: Geological implications; geochemical behaviour of uranium in the supergene environment; uranium exploration techniques; uranium mineralogy; time, crustal evolution and generation of uranium deposits; uranium exploration; geochemistry of uranium in the hydrographic network;

De Vivo

1984-01-01

372

Preparation of uranium compounds  

DOEpatents

UI.sub.3(1,4-dioxane).sub.1.5 and UI.sub.4(1,4-dioxane).sub.2, were synthesized in high yield by reacting turnings of elemental uranium with iodine dissolved in 1,4-dioxane under mild conditions. These molecular compounds of uranium are thermally stable and excellent precursor materials for synthesizing other molecular compounds of uranium including alkoxide, amide, organometallic, and halide compounds.

Kiplinger, Jaqueline L; Montreal, Marisa J; Thomson, Robert K; Cantat, Thibault; Travia, Nicholas E

2013-02-19

373

SEPARATION OF METAL SALTS BY ADSORPTION  

Microsoft Academic Search

It has been found that certain metal salts, particularly the halides of ; iron, cobalt, nickel, and the actinide metals, arc readily absorbed on aluminum ; oxide, while certain other salts, particularly rare earth metal halides, are not ; so absorbed. Use is made of this discovery to separate uranium from the rare ; earths. The metal salts are first

Gruen

1959-01-01

374

Rapid separation of fresh fission products (draft)  

Microsoft Academic Search

The fission of highly eruiched uranium by thermal neutrons creates dozens of isotopic products. The Isotope and Nuclear Chemistry Group participates in programs that involve analysis of 'fiesh' fission products by beta counting following radiochemical separations. This is a laborious and time-consuming process that can take several days to generate results. Gamma spectroscopy can provide a more immediate path to

D. E. Dry; E. Bauer; L. A. Petersen

2003-01-01

375

Uranium provinces of North America; their definition, distribution, and models  

USGS Publications Warehouse

Uranium resources in North America are principally in unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits. Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate and unconformity-related deposits are, respectively, in the Blind River?Elliot Lake (BRELUP) and the Athabasca Basin (ABUP) Uranium Provinces in Canada. Sandstone uranium deposits are of two principal subtypes, tabular and roll-front. Tabular sandstone uranium deposits are mainly in upper Paleozoic and Mesozoic rocks in the Colorado Plateau Uranium Province (CPUP). Roll-front sandstone uranium deposits are in Tertiary rocks of the Rocky Mountain and Intermontane Basins Uranium Province (RMIBUP), and in a narrow belt of Tertiary rocks that form the Gulf Coastal Uranium Province (GCUP) in south Texas and adjacent Mexico. Volcanic uranium deposits are concentrated in the Basin and Range Uranium Province (BRUP) stretching from the McDermitt caldera at the Oregon-Nevada border through the Marysvale district of Utah and Date Creek Basin in Arizona and south into the Sierra de Pe?a Blanca District, Chihuahua, Mexico. Uraniferous phosphorite occurs in Tertiary sediments in Florida, Georgia, and North and South Carolina and in the Lower Permian Phosphoria Formation in Idaho and adjacent States, but only in Florida has economic recovery been successful. The Florida Phosphorite Uranium Province (FPUP) has yielded large quantities of uranium as a byproduct of the production of phosphoric acid fertilizer. Economically recoverable quantities of copper, gold, molybdenum, nickel, silver, thorium, and vanadium occur with the uranium deposits in some provinces. Many major epochs of uranium mineralization occurred in North America. In the BRELUP, uranium minerals were concentrated in placers during the Early Proterozoic (2,500?2,250 Ma). In the ABUP, the unconformity-related deposits were most likely formed initially by hot saline formational water related to diagenesis (?1,400 to 1,330 Ma) and later reconcentrated by hydrothermal events at ?1,280??1,000, ?575, and ?225 Ma. Subsequently in North America, only minor uranium mineralization occurred until after continental collision in Permian time (255 Ma). Three principal epochs of uranium mineralization occurred in the CPUP: (1) ??210?200 Ma, shortly after Late Triassic sedimentation; (2) ??155?150 Ma, in Late Jurassic time; and (3) ??135 Ma, after sedimentation of the Upper Jurassic Morrison Formation. The most likely source of the uranium was silicic volcaniclastics for the three epochs derived from a volcanic island arc at the west edge of the North American continent. Uranium mineralization occurred during Eocene, Miocene, and Pliocene times in the RMIBUP, GCUP, and BRUP. Volcanic activity took place near the west edge of the continent during and shortly after sedimentation of the host rocks in these three provinces. Some volcanic centers in the Sierra de Pe?a Blanca district within the BRUP may have provided uranium-rich ash to host rocks in the GCUP. Most of the uranium provinces in North America appear to have a common theme of close associations to volcanic activity related to the development of the western margin of the North American plate. The south and west margin of the Canadian Shield formed the leading edge of the progress of uranium source development and mineralization from the Proterozoic to the present. The development of favorable hosts and sources of uranium is related to various tectonic elements developed over time. Periods of major uranium mineralization in North America were Early Proterozoic, Middle Proterozoic, Late Triassic?Early Jurassic, Early Cretaceous, Oligocene, and Miocene. Tertiary mineralization was the most pervasive, covering most of Western and Southern North America.

Finch, Warren Irvin

1996-01-01

376

Synthesis of uranium fluorides from uranium dioxide with ammonium bifluoride and ammonolysis of uranium fluorides to uranium nitrides  

Microsoft Academic Search

This work presents the chemical conversion of uranium oxides to uranium fluorides, and their subsequent conversion to uranium nitrides. Uranium dioxide reacts with ammonium bifluoride at 20°C to form compound in the ammonium-uranium fluoride chemical system. This reaction occurs between solid uranium dioxide at the surface of the particles and ammonium fluoride vapor. A shrinking-sphere model demonstrated surface reaction kinetics,

Charles Burnett Yeamans

2008-01-01

377

Chemical Separations  

NSDL National Science Digital Library

This site contains complete notes in a PowerPoint-like presentation for a chemical separations course. It covers a wide variety of topics, including distillation, extraction, gas chromatography, liquid chromatograpy, chromatography theory, instrumentation, electrophoresis, field flow fractionation, and affinity chromatography. It covers these topics thoroughly using a clear, consistent, and simple presentation style. Links to major topics like GC, LC, and electrophoresis provide specific information about the theory, instrumentation, and practice related to these techniques. The site also contains many annimations illustrating important separation processes.

2011-05-18

378

Chalcogels: porous metal-chalcogenide networks from main-group metal ions. Effect of surface polarizability on selectivity in gas separation.  

PubMed

We report the synthesis of metal-chalcogenide gels and aerogels from anionic chalcogenide clusters and linking metal ions. Metal ions such as Sb(3+) and Sn(2+), respectively chelated with tartrate and acetate ligands, react in solution with the chalcogenide clusters to form extended polymeric networks that exhibit gelation phenomena. Chalcogenide cluster anions with different charge densities, such as [Sn(2)S(6)](4-) and [SnS(4)](4-), were employed. In situ rheological measurements during gelation showed that a higher charge density on the chalcogenide cluster favors formation of a rigid gel network. Aerogels obtained from the gels after supercritical drying have BET surface areas from 114 to 368 m(2)/g. Electron microscopy images coupled with nitrogen adsorption measurements showed the pores are micro (below 2 nm), meso (2-50 nm), and macro (above 50 nm) regions. These chalcogels possess band gaps in the range of 1.00-2.00 eV and selectively adsorb polarizable gases. A 2-fold increase in selectivity toward CO(2)/C(2)H(6) over H(2) was observed for the Pt/Sb/Ge(4)Se(10)-containing aerogel compared to aerogel containing Pt(2)Ge(4)S(10). The experimental results suggest that high selectivity in gas adsorption is achievable with high-surface-area chalcogenide materials containing heavy polarizable elements. PMID:20925321

Bag, Santanu; Kanatzidis, Mercouri G

2010-10-27

379

Anomalous occurrence of uranium in alpine peats, Summit County, Colorado, and results of a simple sample fractionation procedure  

USGS Publications Warehouse

Samples from Summit County, Colo., were fractionated for analyses of organic content and uranium. The uranium is related to organic content but not to type of organic matter. In one area uranium values are around 100 ppm in bulk samples and as much as 200 ppm in certain separated fractions of the samples; this is much higher than the 1-10 ppm normal uranium values for peat.

Leventhal, Joel S.; Jennings, Joan K.; Lemke, Alan J.

1978-01-01

380

A comparative study of economical separation and aggregation properties of biologically capped and thiol functionalized gold nanoparticles: selecting the eco-friendly trojan horses for biological applications.  

PubMed

We are presenting facile bio-fabrication of extremely stable gold nanoparticles (GNPs) using medicinal plant Azadirachta indica (commonly called Neem) and its comparison with most commonly used glutathione (GSH) protected GNPs in terms of stability under physiological conditions, seperation using density gradient centrifugation and aggregation properties in the solution. There was dual peak at 536 and 662 nm indicating the presence of non-spherical GNPs including triangles, rods and hexagons in case of A. indica mediated GNPs unlike citrate stabilized GNPs which exhibited single sharp peak. Spherical GNPs were separated from the consortium of uniquely shaped nanoparticles bio-fabricated using A. indica leaf extract using sucrose density gradient centrifugation (SDGC).To comprehend the anti-agglomeration potentials of A. indica leaf mediated GNPs and GSH-GNPs under physiological conditions, flocculation parameters (FP) were calculated and found to be least for A. indica leaf mediated GNPs, indicating their exceptional stability. PMID:23603039

Pandey, Sunil; Thakur, Mukeshchand; Shah, Ritu; Oza, Goldie; Mewada, Ashmi; Sharon, Madhuri

2013-09-01

381

Application of supported liquid membranes for removal of uranium from groundwater  

SciTech Connect

The separation of uranium from Hanford site groundwater as studied by hollow-fiber supported liquid membranes, SLM. The carrier bis(2,4,4-trimethylpentyl)phosphinic acid, H(DTMPep), contained in the commercial extractant Cyanex{trademark} 272 was used as a membrane carrier, because of its selectivity for U over calcium and magnesium. The water soluble complexing agent, 1-hydroxyethane-1,1-diphosphonic acid, HEDPA, was used as stripping agent. Polypropylene hollow-fibers and n-dodecane were used as polymeric support and diluent, respectively. Laboratory scale hollow-fiber modules were employed in a recycling mode, using as feed synthetic groundwater at pH 2, to confirm the capability of the proposed SLM system to separate and concentrate U(VI) in the strip solution. Information was obtained on the U(VI) concentration factor and on the long-term performance of the SLMs. Encouraging results were obtained both with a conventional module and with a module containing a carrier solution reservoir. Industrial scale modules were used at Hanford to test the SLM separation of U(VI) from real contaminated groundwater. The uranium concentration was reduced from approximately 3500 ppB to about 1 ppB in a few hours. 9 refs., 8 figs., 4 tabs.

Chiarizia, R.; Horwitz, E.P.; Rickert, P.G.; Hodgson, K.M. (Argonne National Lab., IL (USA); Westinghouse Hanford Co., Richland, WA (USA))

1989-01-01

382

Predicting 232U Content in Uranium  

SciTech Connect

The minor isotope 232U may ultimately be used for detection or confirmation of uranium in a variety of applications. The primary advantage of 232 U as an indicator of the presence of enriched uranium is the plentiful and penetrating nature of the radiation emitted by its daughter radionuclide 208Tl. A possible drawback to measuring uranium via 232U is the relatively high uncertainty in 232U abundance both within and between material populations. An important step in assessing this problem is to ascertain what determines the 232U concentration within any particular sample of uranium. To this end, we here analyze the production and eventual enrichment of 232 U during fuel-cycle operations. The goal of this analysis is to allow approximate prediction of 232 U quantities, or at least some interpretation of the results of 232U measurements. We have found that 232U is produced via a number of pathways during reactor irradiation of uranium and is subsequently concentrated during the later enrichment of the uranium' s 235U Content. While exact calculations are nearly impossible for both the reactor-production and cascade-enrichment parts of the prediction problem, estimates and physical bounds can be provided as listed below and detailed within the body of the report. Even if precise calculations for the irradiation and enrichment were possible, the ultimate 212U concentration would still depend upon the detailed fuel-cycle history. Assuming that a thennal-diffusion cascade is used to produce highly enriched uranium (HEU), dilution of reactor-processed fuel at the cascade input and the long-term holdup of 232U within the cascade both affect the 232U concentration in the product. Similar issues could be expected to apply for the other isotope-separation technologies that are used in other countries. Results of this analysis are listed below: 0 The 232U concentration depends strongly on the uranium enrichment, with depleted uranium (DU) containing between 1600 and 8000 times less 232U than HEU does. * The 236U/232U concentration ratio in HEU is likely to be between 10{sup 6} and 2 x 10{sup 7}. 0 Plutonium-production reactors yield uranium with between I and 10 ppt of 232u. 0 Much higher 132U concentrations can be obtained in some situations. * Significant variation in the 232U concentration is inevitable. * Cascade enrichment increases the 232U concentration by a factor of at least 200, and possibly as much as 1000. 0 The actual 232U concentration depends upon the dilution at the cascade input.

AJ Peurrung

1999-01-07

383

Battery separator  

Microsoft Academic Search

The invention disclosed relates to a novel paper is a composition for use as a separator material in electrical batteries. The paper composition 30-50%\\/w of glass fibers and 70-59%\\/w of a co-polymer of vinyl chloride and vinyl acetate.

W. A. Armstrong; J. A. Wheat

1980-01-01

384

Separation Group.  

ERIC Educational Resources Information Center

Describes eight-week short-term group designed to help separated or divorced men and women move through related adjustment phase in focused group setting. Discusses constructs that form the foundations of this short-term psychoeducational and support group and presents brief overview of psychological difficulties that occur as result of marital…

Addington, Jean

1992-01-01

385

Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure.  

PubMed

A high-density, polymeric C18 stationary phase (Inertsil ODS-P) or a polymeric C30 phase (Inertsil C30) provided improved resolution of the isomeric fatty acids (FAs), FA methyl esters (FAMEs), triacylglycerols (TAGs), and tocopherols with an increase in pressure of 20-70MPa in reversed-phase HPLC. With respect to isomeric C18 FAMEs with one cis-double bond, ODS-P phase was effective for recognizing the position of a double bond among petroselinic (methyl 6Z-octadecenoate), oleic (methyl 9Z-octadecenoate), and cis-vaccenic (methyl 11Z-octadecenoate), especially at high pressure, but the differentiation between oleic and cis-vaccenic was not achieved by C30 phase regardless of the pressure. A monomeric C18 phase (InertSustain C18) was not effective for recognizing the position of the double bond in monounsaturated FAME, while the separation of cis- and trans-isomers was achieved by any of the stationary phases. The ODS-P and C30 phases provided increased separation for TAGs and ?- and ?-tocopherols at high pressure. The transfer of FA, FAME, or TAG molecules from the mobile phase to the ODS-P stationary phase was accompanied by large volume reduction (-30?-90mL/mol) resulting in a large increase in retention (up to 100% for an increase of 50MPa) and improved isomer separation at high pressure. For some isomer pairs, the ODS-P and C30 provided the opposite elution order, and in each case higher pressure improved the separation. The two stationary phases showed selectivity for the isomers having rigid structures, but only the ODS-P was effective for differentiating the position of a double bond in monounsaturated FAMEs. The results indicate that the improved isomer separation was provided by the increased dispersion interactions between the solute and the binding site of the stationary phase at high pressure. PMID:24666940

Okusa, Kensuke; Iwasaki, Yuki; Kuroda, Ikuma; Miwa, Shohei; Ohira, Masayoshi; Nagai, Toshiharu; Mizobe, Hoyo; Gotoh, Naohiro; Ikegami, Tohru; McCalley, David V; Tanaka, Nobuo

2014-04-25

386

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability  

SciTech Connect

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

Isselhardt, B H

2011-09-06

387

Removal of uranium(VI) from aqueous solution using iminodiacetic acid derivative functionalized SBA-15 as adsorbents.  

PubMed

Three different functional SBA-15 were prepared by a post-grafting method using three iminodiacetic acid derivatives of ethylenediaminetriacetic acid (ED3A), diethylenetriaminetetraacetic acid (DT4A), and 1,2-cyclohexylenedinitrilotriacetic acid (CyD3A), which were used as adsorbents for removal of uranium(vi) from aqueous solution. These materials were characterized by FT-IR, NMR, TEM, nitrogen adsorption/desorption experiments, and elemental analysis. The effect of pH, ionic strength, contact time, solid-liquid ratio, initial metal ion concentration, temperature, and coexisting ions on uranium(vi) sorption behaviors of the functionalized SBA-15 was studied. Typical sorption isotherms (Langmuir and Freundlich) were determined for the sorption process, and the maximum sorption capacity was calculated. The influence of functional groups on uranium(vi) sorption was also discussed. As a result, compared with other current U(vi) sorbents (granite, kaolin, attapulgite), SBA-15-1,2-cyclohexylenedinitrilotriacetic acid (SBA-15-CyD3A) possessed good selective sorption properties, which had potential application in separation of uranium(vi). PMID:24435450

Wang, Yu-Long; Song, Li-Juan; Zhu, Lu; Guo, Bo-Long; Chen, Su-Wen; Wu, Wang-Suo

2014-03-01

388

Investigation of Great Basin big sagebrush and black greasewood as biogeochemical indicators of uranium mineralization. Final report. National Uranium Resource Evaluation  

Microsoft Academic Search

The effects of varying phosphate concentrations in natural aqueous systems upon the uptake of uranium by big sagebrush (Artemesia tridentata subsp. tridentata) and black greasewood (Sarcobatus vermiculatus (Hook) Torr.) were investigated. Two separate growth experiments with five drip-flow hyroponic units were used and plant seedlings were grown for 60 days in solutions of varying phosphate and uranium concentrations. Successful growth

F. E. Diebold; S. McGrath

1982-01-01

389

Uranium metallogenic epochs  

Microsoft Academic Search

The author analyzes the relative distribution of uranium reserves throughout the world in deposits of various origin and age. This serves as a basis for outlining the metallogenic epochs. No data are given on uranium in the Soviet Union, but nevertheless the article appears to be of interest to economic geologists. — E. A. Alexandrov.

N. K. Morozenko

1966-01-01

390

World Uranium Reserves  

NSDL National Science Digital Library

This American Energy Independence website provides a brief overview of potential supplies of uranium for nuclear energy. The author, nuclear engineer James Hopf, believes that there are large reserves of uranium available, and that more will be discovered if needed. Links to literature cited and related resources are included.

Hopf, James; Independence, American E.

391

Uranium in river water  

Microsoft Academic Search

The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains

M. R. Palmer; J. M. Edmond

1993-01-01

392

Uranium: A Dentist's perspective  

PubMed Central

Uranium is a naturally occurring radionuclide found in granite and other mineral deposits. In its natural state, it consists of three isotopes (U-234, U-235 and U-238). On an average, 1% – 2% of ingested uranium is absorbed in the gastrointestinal tract in adults. The absorbed uranium rapidly enters the bloodstream and forms a diffusible ionic uranyl hydrogen carbonate complex (UO2HCO3+) which is in equilibrium with a nondiffusible uranyl albumin complex. In the skeleton, the uranyl ion replaces calcium in the hydroxyapatite complex of the bone crystal. Although in North India, there is a risk of radiological toxicity from orally ingested natural uranium, the principal health effects are chemical toxicity. The skeleton and kidney are the primary sites of uranium accumulation. Acute high dose of uranyl nitrate delays tooth eruption, and mandibular growth and development, probably due to its effect on target cells. Based on all previous research and recommendations, the role of a dentist is to educate the masses about the adverse effects of uranium on the overall as well as the dental health. The authors recommended that apart from the discontinuation of the addition of uranium to porcelain, the Public community water supplies must also comply with the Environmental Protection Agency (EPA) standards of uranium levels being not more than 30 ppb (parts per billion). PMID:24478959

Toor, R. S. S.; Brar, G. S.

2012-01-01

393

6-(Tetrazol-5-yl)-2,2'-bipyridine: a highly selective ligand for the separation of lanthanides(III) and actinides(III).  

PubMed

The coordination structure in the solid state and solution complexation behavior of 6-(tetrazol-5-yl)-2,2'-bipyridine (HN4bipy) with samarium(III) was investigated as a model system for actinide(III)/lanthanide(III) separations. Two different solid 1:2 complexes, [Sm(N4bipy)2(OH)(H2O)2] (1) and [Sm(N4bipy)2(HCOO)(H2O)2] (2), were obtained from the reaction of samarium(III) nitrate with HN4bipy in isopropyl alcohol, resuspension in N,N-dimethylformamide (DMF), and slow crystallization. The formate anion coordinated to samarium in 2 is formed by decomposition of DMF to formic acid and dimethylamine. Time-resolved laser fluorescence spectroscopy (TRLFS) studies were performed with curium(III) and europium(III) by using HN4bipy as the ligand. Curium(III) is observed to form 1:2 and 1:3 complexes with increasing HN4bipy concentration; for europium(III), formation of 1:1 and 1:3 complexes is observed. Although the solid-state samarium complexes were confirmed as 1:2 species the 1:2 europium(III) solution complex in ethanol was not identified with TRLFS. The determined conditional stability constant for the 1:3 fully coordinated curium(III) complex species is more than 2 orders of magnitude higher than that for europium(III) (log ?3[Cm(N4bipy)3] = 13.8 and log ?3[Eu(N4bipy)3] = 11.1). The presence of added 2-bromodecanoic acid as a lipophilic anion source reduces the stability constant for formation of the 1:2 and 1:3 curium(III) complexes, but no ternary complexes were observed. The stability constants for the 1:3 metal ion-N4bipy complexes equate to a theoretical separation factor, SF(Cm(III)/Eu(III)) ? 500. However, the low solubility of the HN4bipy ligand in nonpolar solvents typically used in actinide-lanthanide liquid-liquid extractions prevents its use as a partitioning extractant until a more lipophilic HN4bipy-type ligand is developed. PMID:24967733

Kratsch, Jochen; Beele, Björn B; Koke, Carsten; Denecke, Melissa A; Geist, Andreas; Panak, Petra J; Roesky, Peter W

2014-09-01

394

Preliminary survey of separations technology applicable to the pretreatment of Hanford tank waste (1992--1993)  

SciTech Connect

The US Department of Energy has established the Tank Waste Remediation System (TWRS) to manage and dispose of radioactive wastes stored at the Hanford Site. Within this program are evaluations of pretreatment system alternatives through literature reviews. The information in this report was collected as part of this project at Pacific Northwest Laboratory. A preliminary survey of literature on separations recently entered into the Hanford electronic databases (1992--1993) that have the potential for pretreatment of Hanford tank waste was conducted. Separation processes that can assist in the removal of actinides (uranium, plutonium, americium), lanthanides, barium, {sup 137}Cs, {sup 90}Sr,{sup 129 }I, {sup 63}Ni, and {sup 99}Tc were evaluated. Separation processes of interest were identified through literature searches, journal reviews, and participation in separation technology conferences. This report contains brief descriptions of the potential separation processes, the extent and/or selectivity of the separation, the experimental conditions, and observations. Information was collected on both national and international separation studies to provide a global perspective on recent research efforts.

Lawrence, W.E.; Kurath, D.E.

1994-04-01

395

Electrochromatographic separation of proteins  

NASA Technical Reports Server (NTRS)

We have developed a modified electrochromatography system which minimizes Joule heating at electric field strengths up to 125 V/cm. A non-linear equilibrium model is described which incorporates electrophoretic mobility, hydrodynamic flow velocity, and an electrically induced concentration polarization at the surface of the stationary phase. This model is able to provide useful estimates of protein retention time and velocity in a column packed with Sephadex gel and subjected to an electric field. A correlation of electrophoretic mobility of peptide and proteins with respect to their charge, molecular mass, and asymmetry enables the selection of solute target molecules for electrochromatographic separations. Good separation of protein mixtures have been obtained.

Basak, S. K.; Velayudhan, A.; Kohlmann, K.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

1995-01-01

396

Spectrophotometric determination of uranium in process streams of a uranium extraction plant.  

PubMed

This paper deals with the development and standardization of procedures for the determination of uranium on a routine basis in various process streams of a uranium extraction plant, covering a wide range of concentrations from 350 g 1(-1) down to 5 mg 1(-1) using only a spectrophotometric technique. The self-absorption of uranyl ion in dilute phosphoric acid and the violet-blue colour of the UO(2)(2+)-Arsenazo III complex in 4 M HC1 were exploited for high and low concentrations of uranium, respectively. The methods described were applied to samples of varying nature such as aqueous, organics and solids, involve minimal sample preparation and do not require prior separation of uranium from impurities. The interfering impurities in different process streams were also studied. Large quantities of silica as undissolved material poses a serious interference in the case of UNS and UNF. Considerable quantities of iron in UNS, UNF, UNR and UNRC cause interference. Possible remedies in these cases are suggested. Problems with the direct spectrophotometric measurement of organic samples is discussed. The effect of the presence of large quantities of ammonium nitrate and sodium nitrate in WD samples on the determination of uranium is also discussed. The results are compared with those obtained by volumetry and X-ray fluorescence spectrometry for higher concentrations of uranium and by extraction-spectrophotometry (ethyl acetate-thiocyanate method) for lower concentrations. Relative standard deviation of 1% and 5% for high and low concentrations, respectively, were obtained, which are adequate as far as process stream samples are concerned. The compared results are in fair agreement. The problems associated with the determination of uranium in these process streams are discussed. Experimental results for 10 different process streams normally encountered in a uranium extraction plant are tabulated. PMID:18966745

Murty, B N; Jagannath, Y V; Yadav, R B; Ramamurty, C K; Syamsundar, S

1997-02-01

397

Uranium dioxide electrolysis  

DOEpatents

This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

Willit, James L. (Batavia, IL); Ackerman, John P. (Prescott, AZ); Williamson, Mark A. (Naperville, IL)

2009-12-29

398

16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM RECOVERY PROCESSED RELATIVELY PURE MATERIALS AND SOLUTIONS AND SOLID RESIDUES WITH RELATIVELY LOW URANIUM CONTENT. URANIUM RECOVERY INVOLVED BOTH SLOW AND FAST PROCESSES. (4/4/66) - Rocky Flats Plant, General Manufacturing, Support, Records-Central Computing, Southern portion of Plant, Golden, Jefferson County, CO

399

Gas separating  

DOEpatents

Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

Gollan, Arye Z. [Newton, MA

1990-12-25

400

Gas separating  

DOEpatents

Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

Gollan, Arye (Newton, MA)

1988-01-01

401

Separation system  

DOEpatents

A separation system for dewatering radioactive waste materials includes a disposal container, drive structure for receiving the container, and means for releasably attaching the container to the drive structure. Separation structure disposed in the container adjacent the inner surface of the side wall structure retains solids while allowing passage of liquids. Inlet port structure in the container top wall is normally closed by first valve structure that is centrifugally actuated to open the inlet port and discharge port structure at the container periphery receives liquid that passes through the separation structure and is normally closed by second valve structure that is centrifugally actuated to open the discharge ports. The container also includes coupling structure for releasable engagement with the centrifugal drive structure. Centrifugal force produced when the container is driven in rotation by the drive structure opens the valve structures, and radioactive waste material introduced into the container through the open inlet port is dewatered, and the waste is compacted. The ports are automatically closed by the valves when the container drum is not subjected to centrifugal force such that containment effectiveness is enhanced and exposure of personnel to radioactive materials is minimized.

Rubin, Leslie S. (Newton, MA)

1986-01-01

402

Selective separation of rare earth metals by solvent extraction in the presence on new hydrophilic chelating polymers functionalized with ethylenediaminetetraacetic acid. I. Development of new hydrophilic chelating polymers and their adsorption properties for rare earth metals  

SciTech Connect

New hydrophilic chelating polymers were synthesized by introducing ethylenediaminetetraacetic acid (EDTA) onto water-soluble polyallylamine. The selective separation of rare earth metals by solvent extraction including these chelating polymers in the aqueous phase is the goal of this work. The polymers were characterized by IR analysis, elemental analysis, gel permeation chromatography (GPC) measurement, and pH titration. Two kinds of polymers with different solubilities in water were produced using different solvents. Both polymers were naturally precipitated in the presence of rare earth metals. This suggests that in the solvent extraction system including these chelating polymers, the recovery of the polymers is easy. Adsorption properties of Y{sup 3+} and Er{sup 3+} on these polymers were also investigated. The separation properties by adsorption on the polymers were comparable to those by EDTA. The chelating polymers had the characteristics that their separation factors decreased by adsorption and the total amount adsorbed increased with increasing pH or initial metal concentrations, although in the presence of EDTA these properties were found to be almost constant.

Matsuyama, Hideto; Miyamoto, Yoshikazu; Teramoto, Masaaki [Kyoto Inst. of Technology, Kyoto (Japan)

1996-03-01

403

Simulation of diffusion of oxygen and uranium in uranium dioxide nanocrystals  

NASA Astrophysics Data System (ADS)

The method of molecular dynamics is used to study phase transitions and ion transport phenomena in uranium dioxide nanocrystals. The temperature dependences of uranium and oxygen diffusion coefficients in the range from 2280 to 3950 K are calculated separately for surface, near-surface and bulk regions of the crystals. On these dependences we have distinguished temperature intervals, which correspond to crystalline phase, superionic state and melt. The activation energies of diffusion and pre-exponential factors for these intervals are determined. The obtained results are compared with experimental data and calculations of other authors.

Kupryazhkin, A. Ya.; Zhiganov, A. N.; Risovany, D. V.; Nekrassov, K. A.; Risovany, V. D.; Golovanov, V. N.

2008-01-01

404

Spallation studies on shock loaded uranium  

SciTech Connect

Several spallation experiments have been performed on uranium using gas gun driven normal plate impacts with, VISAR instrumentation and soft recovery. The shock pressures achieved were 81, 53, and 37 kbar. This paper will focus on modeling the free surface particle velocity trace U with of 300 ppm carbon using the 1 d characteristics code CHARADE. The spallation model involves the growth and coalescence of brittle cracks. Metallographical examination of recovered samples and details of the experimental apparatus are discussed in separate papers.

Tonks, D.L.; Hixson, R.; Gustavsen, R.L.; Vorthman, J.E.; Kelly, A.; Zurek, A.K.; Thissell, W.R.

1997-12-01

405

Fission enhanced diffusion of uranium in zirconia  

NASA Astrophysics Data System (ADS)

This paper deals with the comparison between thermal and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding tubes. The experiments under irradiation are performed at the Institut Laue Langevin (ILL) in Grenoble using the Lohengrin spectrometer. A thin 235UO 2 layer in direct contact with an oxidised zirconium foil is irradiated in the ILL high flux reactor. The fission product flux is about 10 11 ions cm -2 s -1 and the target temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion coefficient in zirconia from the energy distribution broadening of two selected fission products. It is found to be equal to 10 -15 cm 2 s -1 at 480 °C and compared to uranium thermal diffusion data in ZrO 2 in the same pressure and temperature conditions. The FED results are analysed in comparison with literature data.

Bérerd, N.; Chevarier, A.; Moncoffre, N.; Sainsot, Ph.; Faust, H.; Catalette, H.

2005-11-01

406

Fission Enhanced diffusion of uranium in zirconia  

E-print Network

This paper deals with the comparison between thermal and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding tubes. The experiments under irradiation are performed at the Institut Laue Langevin (ILL) in Grenoble using the Lohengrin spectrometer. A thin $^{235}UO\\_2$ layer in direct contact with an oxidized zirconium foil is irradiated in the ILL high flux reactor. The fission product flux is about 10$^{11}$ ions cm$^{-2}$ s$^{-1}$ and the target temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion coefficient in zirconia from the energy distribution broadening of two selected fission products. It is found to be equal to 10$^{-15}$ cm$^2$ s$^{-1}$ at 480$\\circ$C and compared to uranium thermal diffusion data in ZrO$\\_2$ in the same pressure and temperature conditions. The FED results are analysed in comparison with literature data.

Bérerd, N; Moncoffre, N; Sainsot, P; Faust, H; Catalette, H

2005-01-01

407

Developments in uranium in 1981  

Microsoft Academic Search

Declining prices and increasing costs continued to influence the uranium industry during 1981. The supply of uranium exceeds the current demand and, as a result, exploration for uranium declined in the United States for the third straight year. During 1981, 107 companies spent $144.8 million on uranium exploration, which included 14.1 million ft of surface drilling. This drilling was mainly

Chenoweth

1982-01-01

408

Developments in uranium in 1982  

Microsoft Academic Search

Slippage in demand, increasing costs, and low spot market prices continued to influence the uranium industry during 1982. The supply of uranium exceeds the current demand and, as a result, exploration for uranium declined in the United States for the fourth straight year. During 1982, 92 companies spent $73.86 million on uranium exploration, including 6.1 million ft of surface drilling.

Chenoweth

1983-01-01

409

Cell-selective knockout and 3D confocal image analysis reveals separate roles for astrocyte-and endothelial-derived CCL2 in neuroinflammation  

PubMed Central

Background Expression of chemokine CCL2 in the normal central nervous system (CNS) is nearly undetectable, but is significantly upregulated and drives neuroinflammation during experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis which is considered a contributing factor in the human disease. As astrocytes and brain microvascular endothelial cells (BMEC) forming the blood–brain barrier (BBB) are sources of CCL2 in EAE and other neuroinflammatory conditions, it is unclear if one or both CCL2 pools are critical to disease and by what mechanism(s). Methods Mice with selective CCL2 gene knockout (KO) in astrocytes (Astro KO) or endothelial cells (Endo KO) were used to evaluate the respective contributions of these sources to neuroinflammation, i.e., clinical disease progression, BBB damage, and parenchymal leukocyte invasion in a myelin oligodendrocyte glycoprotein peptide (MOG35-55)-induced EAE model. High-resolution 3-dimensional (3D) immunofluorescence confocal microscopy and colloidal gold immuno-electron microscopy were employed to confirm sites of CCL2 expression, and 3D immunofluorescence confocal microscopy utilized to assess inflammatory responses along the CNS microvasculature. Results Cell-selective loss of CCL2 immunoreactivity was demonstrated in the respective KO mice. Compared to wild-type (WT) mice, Astro KO mice showed reduced EAE severity but similar onset, while Endo KO mice displayed near normal severity but significantly delayed onset. Neither of the KO mice showed deficits in T cell proliferation, or IL-17 and IFN-? production, following MOG35-55 exposure in vitro, or altered MOG-major histocompatibility complex class II tetramer binding. 3D confocal imaging further revealed distinct actions of the two CCL2 pools in the CNS. Astro KOs lacked the CNS leukocyte penetration and disrupted immunostaining of CLN-5 at the BBB seen during early EAE in WT mice, while Endo KOs uniquely displayed leukocytes stalled in the microvascular lumen. Conclusions These results point to astrocyte and endothelial pools of CCL2 each regulating different stages of neuroinflammation in EAE, and carry implications for drug delivery in neuroinflammatory disease. PMID:24444311

2014-01-01

410

National uranium resource evaluation, Marble Canyon Quadrangle, Arizona and Utah  

SciTech Connect

The Marble Canyon Quadrangle (2/sup 0/), northeast Arizona, was evaluated to a depth of 1500 m for uranium favorability using National Uranium Resource Evaluation criteria. Known mines and prospects were examined; field reconnaissance was done in selected areas of the quadrangle; and a ground-water geochemical survey was made in the southeast third of the quadrangle. The Shinarump and Petrified Forest Members of the Triassic Chinle Formation, which is exposed in the western and northeastern parts of the quadrangle and is present beneath the surface of much of the quadrangle, were found favorable for channel-sandstone uranium deposits. A portion of the Cretaceous Toreva Formation in the southeast part of the quadrangle was found favorable for peneconcordant-sandstone uranium deposits. The western part of the quadrangle was found favorable for uranium concentrations in breccia pipes.

Field, M T; Blauvelt, R P

1982-05-01

411

High resolution characterization of uranium in sediments by DGT and DET techniques ACA-S-12-2197.  

PubMed

Diffusive equilibrium (DET) and diffusive gradient in thin film (DGT) techniques with an inductively coupled plasma mass spectrometry detection of elements were applied to characterize uranium, manganese, iron and (238)U/(235)U isotopic ratio depth profiles in sediment pore water at high spatial resolution and to monitor uranium uptake/remobilization processes in uranium spiked sediment core samples under laboratory, well controlled conditions. Modified constrained sediment DGT probes, packed with Spheron-Oxin(®) resin gel, were employed for selective uranium measurements. Spatially resolved DET and DGT responses were indicative of local redistribution of uranium in naturally uranium poor and rich sediments. PMID:23340286

Gregusova, Michaela; Docekal, Bohumil

2013-02-01

412

Determination of ¹³?Cs and ¹³?Cs/¹³?Cs atomic ratio in environmental samples by combining ammonium molybdophosphate (AMP)-selective Cs adsorption and ion-exchange chromatographic separation to triple-quadrupole inductively coupled plasma-mass spectrometry.  

PubMed

Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011, the activity ratio of (134)Cs/(137)Cs has been widely used as a tracer for contamination source identification. However, because of the short half-life of (134)Cs (2.06 y), this tracer will become unavailable in the near future. This article presents an analytical method for the determination of the long-lived (135)Cs (t(2/1) = 2 × 10(6) y) and the atomic ratio of (135)Cs/(137)Cs, as a promising geochemical tracer, in environmental samples. The analytical method involves ammonium molybdophosphate (AMP)-selective adsorption of Cs and subsequent two-stage ion-exchange chromatographic separation, followed by detection of isolated radiocesium isotopes via triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-MS/MS). The AMP-selective adsorption of Cs and the chromatographic separation system showed high decontamination factors (10(4)-10(5)) for interfering elements, such as Ba, Mo, Sb, and Sn. Using ICP-MS/MS, only selected ions enter the collision/reaction cell to react with N2O, reducing the isobaric interferences ((135)Ba(+) and (137)Ba(+)) and polyatomic interferences ((95) Mo(40)Ar(+), (97) Mo(40)Ar(+), (119)Sn(16)O(+), and (121)Sb(16)O(+)) produced by sample matrix ions. The high abundance sensitivity (10(-9) for the (135)Cs/(133)Cs ratio) provided by ICP-MS/MS allowed reliable analysis of (135)Cs and (137)Cs isotopes with the lowest detection limits ever reported by mass counting methods (0.01 pg mL(-1) and 0.006 pg mL(-1), respectively). The developed analytical method was successfully applied to the determination of (135)Cs and (137)Cs isotopes in environmental samples (soil, litter, and lichen) collected after the FDNPP accident for contamination source identification. PMID:24931104

Zheng, Jian; Bu, Wenting; Tagami, Keiko; Shikamori, Yasuyuki; Nakano, Kazumi; Uchida, Shigeo; Ishii, Nobuyoshi

2014-07-15

413

India's Worsening Uranium Shortage  

SciTech Connect

As a result of NSG restrictions, India cannot import the natural uranium required to fuel its Pressurized Heavy Water Reactors (PHWRs); consequently, it is forced to rely on the expediency of domestic uranium production. However, domestic production from mines and byproduct sources has not kept pace with demand from commercial reactors. This shortage has been officially confirmed by the Indian Planning Commission’s Mid-Term Appraisal of the country’s current Five Year Plan. The report stresses that as a result of the uranium shortage, Indian PHWR load factors have been continually decreasing. The Uranium Corporation of India Ltd (UCIL) operates a number of underground mines in the Singhbhum Shear Zone of Jharkhand, and it is all processed at a single mill in Jaduguda. UCIL is attempting to aggrandize operations by establishing new mines and mills in other states, but the requisite permit-gathering and development time will defer production until at least 2009. A significant portion of India’s uranium comes from byproduct sources, but a number of these are derived from accumulated stores that are nearing exhaustion. A current maximum estimate of indigenous uranium production is 430t/yr (230t from mines and 200t from byproduct sources); whereas, the current uranium requirement for Indian PHWRs is 455t/yr (depending on plant capacity factor). This deficit is exacerbated by the additional requirements of the Indian weapons program. Present power generation capacity of Indian nuclear plants is 4350 MWe. The power generation target set by the Indian Department of Atomic Energy (DAE) is 20,000 MWe by the year 2020. It is expected that around half of this total will be provided by PHWRs using indigenously supplied uranium with the bulk of the remainder provided by breeder reactors or pressurized water reactors using imported low-enriched uranium.

Curtis, Michael M.

2007-01-15

414

Separating natural responses from experimental artefacts: habitat selection by a diadromous fish species using odours from conspecifics and natural stream water.  

PubMed

Animals use sensory stimuli to assess and select habitats, mates and food as well as to communicate with other individuals. One way they do this is to use olfaction, whereby they identify and respond to chemical cues. All organisms release odours, which mix with other chemical substances and ambient environmental conditions. The result is that animals are frequently immersed in a complex, highly dynamic sensory environment where they must identify and respond to only some of the potential stimuli they encounter in the face of significant levels of background noise. Understanding how organisms respond to different chemical cues is therefore dependent on knowing how these responses might be influenced by potential interactions with other stimuli. To test this, we examined whether the diadromous fish Galaxias maculatus was attracted to conspecific odours and whether this response differed when cues were offered in an artificial environment lacking other potential chemical stimuli (tap water) or a more natural background environment (stream water). We found that (1) fish responded to both natural stream water odours and those from conspecifics but the response to the latter was stronger; (2) the attraction to conspecific odours was stronger in tap water than in stream water, which indicates the importance of these odours may be overestimated when they are offered in artificial media. We also conducted a brief literature review, which confirmed that artificial media are commonly used in experiments and that the background environment is often not considered. Our results show that future research testing the responses of organisms to auditory, olfactory and visual cues should carefully consider the context in which cues are presented. Without doing so, such studies may inaccurately assess the importance of sensory cues in natural situations in the wild. PMID:19139923

Hale, Robin; Swearer, Stephen E; Downes, Barbara J

2009-03-01

415

Recovery of uranium values  

SciTech Connect

A process and apparatus are described for stripping uranium values from a uranium-loaded organic extractant phase containing, usually, a tertiary amine capable of forming organic-soluble uranium complexes. The sulphate-containing aqueous strip liquor is fed in co-current with the extractant phase to be stripped through a number of mixing stages in series connected one to another without intermediate settling stages and finally to a final settling stage. A ''primary'' dispersion is maintained in each mixing stage and controlled stepwise ph adjustment of the mixing stages is effected by metered addition of a base, such as ammonia.

Rowden, G.A.

1980-02-12

416

Depleted uranium management alternatives  

SciTech Connect

This report evaluates two management alternatives for Department of Energy depleted uranium: continued storage as uranium hexafluoride, and conversion to uranium metal and fabrication to shielding for spent nuclear fuel containers. The results will be used to compare the costs with other alternatives, such as disposal. Cost estimates for the continued storage alternative are based on a life-cycle of 27 years through the year 2020. Cost estimates for the recycle alternative are based on existing conversion process costs and Capital costs for fabricating the containers. Additionally, the recycle alternative accounts for costs associated with intermediate product resale and secondary waste disposal for materials generated during the conversion process.

Hertzler, T.J.; Nishimoto, D.D.

1994-08-01

417

Coulometric determination of uranium with a platinum working electrode.  

PubMed

Experimental conditions have been established which enable uranium to be determined coulometrically by the reduction of uranium(VI) to uranium(IV) at a platinum working electrode, by controlled-potential or controlled-potential-limit techniques. The procedure has been used successfully as a subsidiary method in the routine determination of uranium in pure uranyl nitrate solutions. The platinum electrode has several important practical advantages over the well established mercury-pool electrode for the coulometric determination of uranium. The consecutive determination of iron(III) and uranium(VI), or plutonium(IV) and uranium(VI) can be carried out with the same working electrode in the same solution and the coulometric oxidation of uranium(IV) to uranium(VT) is practicable. The rate of stirring of the cell liquor is much less critical in the case of the platinum electrode. Two main problems had to be overcome before a practical procedure could be achieved; hydrogen evolution during the uranium(VI)-(IV) reduction had to be eliminated so that 100% current efficiency could be obtained for the desired reaction and electrode-surface poisoning phenomena had to be controlled so that reaction times could be kept reasonably short. It was found that selection of a hydrochloric acid base solution containing a small amount of bismuth(III) enabled hydrogen evolution to be avoided: also electrode-surface poisoning with this base solution was not particularly serious and could be maintained at a satisfactorily low level by occasionally anodizing the electrode in dilute sulphuric acid. Bismuth(III) forms a complex with chloride ions and its presence increases the hydrogen overvoltage at the working electrode: no visible deposit of bismuth metal forms on the electrode during the uranium reduction. Samples containing nitrate can be analysed provided sulphamic acid is added to this hydrochoric acid base solution. PMID:18960821

Davies, W; Gray, W; McLeod, K C

1970-10-01

418

Methane/nitrogen separation process  

DOEpatents

A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

Baker, Richard W. (Palo Alto, CA); Lokhandwala, Kaaeid A. (Menlo Park, CA); Pinnau, Ingo (Palo Alto, CA); Segelke, Scott (Mountain View, CA)

1997-01-01

419

Methane/nitrogen separation process  

DOEpatents

A membrane separation process is described for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. The authors have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen. 11 figs.

Baker, R.W.; Lokhandwala, K.A.; Pinnau, I.; Segelke, S.

1997-09-23

420

Controlling intake of uranium in the workplace: Applications of biokinetic modeling and occupational monitoring data  

SciTech Connect

This report provides methods for interpreting and applying occupational uranium monitoring data. The methods are based on current international radiation protection guidance, current information on the chemical toxicity of uranium, and best available biokinetic models for uranium. Emphasis is on air monitoring data and three types of bioassay data: the concentration of uranium in urine; the concentration of uranium in feces; and the externally measured content of uranium in the chest. Primary Reference guidance levels for prevention of chemical effects and limitation of radiation effects are selected based on a review of current scientific data and regulatory principles for setting standards. Generic investigation levels and immediate action levels are then defined in terms of these primary guidance levels. The generic investigation and immediate actions levels are stated in terms of radiation dose and concentration of uranium in the kidneys. These are not directly measurable quantities, but models can be used to relate the generic levels to the concentration of uranium in air, urine, or feces, or the total uranium activity in the chest. Default investigation and immediate action levels for uranium in air, urine, feces, and chest are recommended for situations in which there is little information on the form of uranium taken into the body. Methods are prescribed also for deriving case-specific investigation and immediate action levels for uranium in air, urine, feces, and chest when there is sufficient information on the form of uranium to narrow the range of predictions of accumulation of uranium in the main target organs for uranium: kidneys for chemical effects and lungs for radiological effects. In addition, methods for using the information herein for alternative guidance levels, different from the ones selected for this report, are described.

Leggett, Richard Wayne [ORNL; Eckerman, Keith F [ORNL; McGinn, Wilson [ORNL; Meck, Dr. Robert A. [U.S. Nuclear Regulatory Commission

2012-01-01

421

Remedial action plan for the inactive uranium processing site at Naturita, Colorado. Remedial action selection report: Attachment 2, geology report; Attachment 3, ground water hydrology report; Attachment 4, supplemental information  

SciTech Connect

The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the U.S. Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), 42 USC {section} 7901 et seq. Part of the UMTRCA requires that the U.S. Nuclear Regulatory Commission (NRC) concur with the DOE`s remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the U.S. Environmental Protection Agency (EPA). This RAP serves two purposes. First, it describes the activities that are proposed by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium processing site near Naturita, Colorado. Second, this RAP, upon concurrence and execution by the DOE, the state of Colorado, and the NRC, becomes Appendix B of the cooperative agreement between the DOE and the state of Colorado.

NONE

1998-03-01

422

Uranium purchases report 1993  

SciTech Connect

Data reported by domestic nuclear utility companies in their responses to the 1991 through 1993 ``Uranium Industry Annual Survey,`` Form EIA-858, Schedule B,`` Uranium Marketing Activities,`` are provided in response to the requirements in the Energy Policy Act 1992. Appendix A contains an explanation of Form EIA-858 survey methodologies with emphasis on the processing of Schedule B data. Additional information published in this report not included in Uranium Purchases Report 1992, includes a new data table. Presented in Table 1 are US utility purchases of uranium and enrichment services by origin country. Also, this report contains additional purchase information covering average price and contract duration. Table 2 is an update of Table 1 and Table 3 is an update of Table 2 from the previous year`s report. The report contains a glossary of terms.

Not Available

1994-08-10

423