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1

SELECTIVE SEPARATION OF URANIUM FROM FERRITIC STAINLESS STEELS  

DOEpatents

A process is described for separating uranium from a nuclear fuel element comprising a uranium-containing core and a ferritic stainless steel clad by heating said element in a non-carburizing atmosphere at a temperature in the range 850-1050 un. Concent 85% C, rapidly cooling the heated element through the temperature range 815 un. Concent 85% to 650 EC to avoid annealing said steel, and then contacting the cooled element with an aqueous solution of nitric acid to selectively dissolve the uranium. (AEC)

Beaver, R.J.; Cherubini, J.H.

1963-05-14

2

Two stage selective oxidative leach method to separately recover uranium and refractory uranium-mineral complexes  

SciTech Connect

The present invention relates to a process for the recovery of uranium and other minerals from uranium ore where at least part of the uranium is present as refractory uranium-mineral complexes, comprising subjecting the uranium ore to mild oxidative carbonate leach fluid to dissolve and remove readily soluble uranium minerals, subsequently subjecting the uranium ore to an oxidative chemically severe leaching system to dissolve and remove the refractory uranium-mineral complexes, and separating and recovering the uranium and other mineral species in the leachate fluids. The process may be applied to in-situ uranium leaching operations or to surface leaching operations.

Tsui, T.F.

1984-03-20

3

SELECTIVE SEPARATION OF URANIUM FROM THORIUM, PROTACTINIUM AND FISSION PRODUCTS BY PEROXIDE DISSOLUTION METHOD  

DOEpatents

A method is described for separating U/sup 233/ from thorium and fission products. The separation is effected by forming a thorium-nitric acid solution of about 3 pH, adding hydrogen peroxide to precipitate uranium and thorium peroxide, treating the peroxides with sodium hydroxide to selectively precipitate the uranium peroxide, and reacting the separated solution with nitric acid to re- precipitate the uranium peroxide.

Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

1959-08-18

4

Separation of uranium isotopes  

SciTech Connect

Methods and apparatus for separation of uranium isotopes by selective isotopic excitation of photochemically reactive uranyl salt source material at cryogenic temperatures, followed by chemical separation of selectively photochemically reduced U/sup +4/ thereby produced from remaining uranyl source material.

Porter, J.T. II

1984-03-27

5

Method for the separation of uranium isotope compounds already converted isotope-selectively  

SciTech Connect

Separation of heavier uranium isotope compounds from lighter uranium isotope compounds in a gas jet having supersonic velocity after one isotope is converted selectively by laser radiation. The gas jet is subjected to an oblique compression shock to abruptly change direction causing the lighter isotope compounds to be deflected unrestrained by guiding walls with the heavier isotope compounds continuing on substantially in the original direction of the gas jet. The heavier isotope compounds are collected in a collecting vessel.

Niemann, H.J.; Sprehe, J.

1985-04-23

6

URANIUM SEPARATION PROCESS  

DOEpatents

A method of separating uranium oxides from PuO/sub 2/, ThO/sub 2/, and other actinide oxides is described. The oxide mixture is suspended in a fused salt melt and a chlorinating agent such as chlorine gas or phosgene is sparged through the suspension. Uranium oxides are selectively chlorinated and dissolve in the melt, which may then be filtered to remove the unchlorinated oxides of the other actinides. (AEC)

Lyon, W.L.

1962-04-17

7

URANIUM SEPARATION PROCESS  

DOEpatents

The separation of uranium from an aqueous solution containing a water soluble uranyl salt is described. The process involves adding an alkali thiocyanate to the aqueous solution, contacting the resulting solution with methyl isobutyl ketons and separating the resulting aqueous and organic phase. The uranium is extracted in the organic phase as UO/sub 2/(SCN)/sub/.

McVey, W.H.; Reas, W.H.

1959-03-10

8

SEPARATION OF THORIUM FROM URANIUM  

DOEpatents

A description is given for the separation of thorium from uranium by forming an aqueous acidic solution containing ionic species of thorium, uranyl uranium, and hydroxylamine, flowing the solution through a column containing the phenol-formaldehyde type cation exchange resin to selectively adsorb substantially all the thorium values and a portion of the uranium values, flowing a dilute solution of hydrochloric acid through the column to desorb the uranium values, and then flowing a dilute aqueous acidic solution containing an ion, such as bisulfate, which has a complexing effect upon thortum through the column to desorb substantially all of the thorium.

Bane, R.W.

1959-09-01

9

Separation of Zirconium and Uranium.  

National Technical Information Service (NTIS)

This invention relates to separation and recovery of zirconium from aqueous solutions containing zirconium and uranium. Separation of zirconium from uranium is, however, difficult since the uranium tends to accompany the zirconium in the solvent extractio...

H. G. Henry

1981-01-01

10

Separation of Zirconium and Uranium.  

National Technical Information Service (NTIS)

Zirconium- and uranium-containing hydrocarbon-amine solutions are treated for separation of zirconium and uranium by means of a process comprising: (1) selctive stripping of zirconium with an aqueous chloride solution, and (2) scrubbing the resulting aque...

D. J. MacDonald H. G. Henry

1982-01-01

11

METHOD OF SEPARATING URANIUM SUSPENSIONS  

DOEpatents

A process is presented for separating colloidally dissed uranium oxides from the heavy water medium in upwhich they are contained. The method consists in treating such dispersions with hydrogen peroxide, thereby converting the uranium to non-colloidal UO/sub 4/, and separating the UO/sub 4/ sfter its rapid settling.

Wigner, E.P.; McAdams, W.A.

1958-08-26

12

Separation Equipment for Uranium Isotopes.  

National Technical Information Service (NTIS)

Separation equipment for uranium isotopes consists of a first laser using a rare gas or a rare gas compound as its active substance; a second, tunable laser which is subjected to photoexcitation by the first laser; a device for generating uranium vapor; a...

M. Yamamoto

1977-01-01

13

Chemical separation method for uranium isotopes  

SciTech Connect

This patent describes a process for isotopic enrichment of uranium. The steps of this process are: (A) preparing a solution of a uranium compound and solvent characterized in that the uranium compound involves a mixture of uranium isotopes. The isotopic mixture is to be enriched and the uranium compound is further characterized in that it possesses at least one excited state in solution. The respective isotopes in the excited state preferentially react at different rates by virtue of dissimilar nuclear magnetic moment contributions to the chemical kinetics of the excited state reactions and the chemical reactions of the excited state lead to the isolation of a phase that possesses a uranium isotopic distribution characteristic of enrichment, the uranium compound being the uranyl ion in the presence of at least one complexing ligand, the ligand being selected from the group consisting of CO/sub 3//sup 2 -/, O/sub 2//sup 2 -/, F/sup -/, Ch/sub 3/Coo/sup -/, C/sub 2/O/sub 4//sup 2 -/, and H/sub 2/O; (B) exciting the uranium compound in solution thus promoting the chemical reaction that preferentially forms the isolated phase containing the enriched uranium isotopic distribution the excitation involving photolysis of the complexed uranyl ion; and (C) separating the enriched phase thus recovering enriched uranium.

Peterson, S.H.; Phillips, D.C.

1986-01-28

14

Study on selective separation of uranium(VI) by new N,N-dialkyl carboxy-amides  

SciTech Connect

The Feasibility study (FS) on commercialized FR cycle systems has been carried out in Japan. In this Feasibility study, 'Advanced Aqueous' reprocessing was designed as a new reprocessing concept to enhance nuclear non-proliferation by recycling U, Pu and minor actinides (MA) with some fission products (FP). The crystallization and U(VI)/TRU(transuranics) co-extraction technique have been selected as candidate technique in the 'Advanced Aqueous' reprocessing. In JAEA, the result of Feasibility study was received and Fast Reactor Cycle Technology Development Project (FaCT) was started. In the nuclear spent fuel reprocessing, FBR spent fuels will coexist with LWR spent fuels for several decades until FBR cycle begins to operate. For the treatment of LWR spent fuels, high decontamination factor for FP was required for U(VI) storage, and solvent extraction technique was selected in the nuclear fuel treatment. In our laboratory, N,N-di-alkyl carboxy-amides have been developed as extractant based on solvent extraction technique for one of a back-up technology of 'Advanced Aqueous' reprocessing in FBR spent fuel treatments. N,N-di-alkyl carboxy-amides were noted as one of the alternative extractant of tri-butylphosphate (TBP) in the field of nuclear fuel reprocessing. Extraction behavior of U(VI) and Pu(IV) with N,N-di-alkyl carboxy-amides was almost similar to those with TBP. N,N-di-alkyl carboxy-amides have some advantages, namely, their complete incinerability (CHON principle) and high stability for hydrolysis and radiolysis. Their main degradation products are carboxylic acids and secondary amines which hardly affect the separation of U(VI) and Pu(IV) from fission products. Further, the synthesis of N,N-di-alkyl carboxy-amides was relatively easy with reaction of carboxylic chloride and secondary amine. The main purpose of this solvent extraction technique using N,N-di-alkyl carboxy-amides is selective separation of Uranium(VI) with branched N,N-di-alkyl carboxy-amides and group separation of Pu-Np linear alkyl type N,N-di-alkyl carboxy-amide for FBR and LWR spent fuel treatment. Since the branched alkyl type N,N-di-alkyl carboxy-amides have the steric hindrance on the complexation with metal cations, branched alkyl type N,N-di-alkyl carboxy-amides can be used to separate An(VI) from An(IV). On the other hand, linear type N,N-di-alkyl carboxy-amides have potential for alternative extractant for tri-butyl phosphate(TBP) because linear type N,N-di-alkyl-amide can extract An(VI) and An(IV). In our previous research work, we have proposed N,N-di-(2- ethyl)hexyl-(2,2-dimethyl)-propanamide (D2EHDMPA) as a candidate extractant for uranium selective separation in FBR spent fuel treatments. However D2EHDMPA was able to separate uranium(VI) from plutonium(IV) and neptunium(VI), D2EHDMPA showed poor U(VI) loading capacity in organic phase. For the purpose of improvement of U(VI) loading capacity in organic phase, nineteenth kinds of New N,N-di-alkyl-amides: N,N-di-hexyl-(3,3-dimethyl)butanamide (DHDMBA), N,N-di-oxyl-(3,3-dimethyl)butanamide (DODMBA), N,N-di-hexyl-(2,2-dimethyl)propanamide (DHDMPA) N,N-di-octyl-(2,2-dimethyl)propanamide (DODMPA), N,N-di-octyl-(2-ethyl)butanamide (DO2EBA), N,N-di-hexyl-(2-ethyl)butanamide (DH2EBA), N-benzyl-N-R{sub 1}-(2-ethyl)hexanamide (R{sub 1}:- C{sub 4}H{sub 9}, -C{sub 6} H{sub 13}, -C{sub 8} H{sub 17}, N-cyclohexyl-N-R{sub 1}-(2- ethyl)hexanamide (R{sub 1}:-C{sub 4}H{sub 9}, -C{sub 6} H{sub 13}, -C{sub 8} H{sub 17}), N-phenyl- N-R{sub 1}-(2-ethyl)hexanamide (R{sub 1}:-C{sub 3}H{sub 9}, -C{sub 4} H{sub 9}, -C{sub 5} H{sub 11}, - C{sub 6}H{sub 13}, -C{sub 8}H{sub 17}, N-(2-ethyl)hexyl-N-Phenyl-octanamide, N-Benzyl- N-Phenyl-(2-ethyl)hexanamide are synthesized. In this paper, our experimental results of new N,N-dialkyl carboxy-amides extraction property of U(VI)/Pu(IV), extraction of macro amount of U(VI), and gamma-ray radiolysis will be summarized. Solvent extraction of U(VI) and Pu (IV) by nineteenth kinds of new N,N-di-alkyl carboxy-amides, macro amount of U(VI) extraction and radiolysis of four c

Suzuki, Shinichi; Sugo, Yumi; Kimura, Takaumi [Japan Atomic Energy Agency: 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Yaita, Tsuyoshi [Japan Atomic Energy Agency: 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Japan Atomic Energy Agency:1-1 koto, Sayo-tyou, Sayo-gun, Hyogo 679-5148 (Japan)

2007-07-01

15

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

16

SEPARATION OF URANIUM, PLUTONIUM, AND FISSION PRODUCTS  

DOEpatents

Uranium and plutonium can be separated from neutron-lrradiated uranium by a process consisting of dissolvlng the lrradiated material in nitric acid, saturating the solution with a nitrate salt such as ammonium nitrate, rendering the solution substantially neutral with a base such as ammonia, adding a reducing agent such as hydroxylamine to change plutonium to the trivalent state, treating the solution with a substantially water immiscible organic solvent such as dibutoxy diethylether to selectively extract the uranium, maklng the residual aqueous solutlon acid with nitric acid, adding an oxidizing agent such as ammonlum bromate to oxidize the plutonium to the hexavalent state, and selectlvely extracting the plutonium by means of an immlscible solvent, such as dibutoxy dlethyletber.

Spence, R.; Lister, M.W.

1958-12-16

17

Laser separation of uranium chosen for scaleup. [Atomic vapor laser isotope separation, molecular laser isotope separation plasma separation process  

Microsoft Academic Search

Atomic vapor laser isotope separation (AVLIS) has been selected by the Department of Energy to go into large-scale engineering development and demonstration over two other advanced technologies, molecular laser isotope separation and plasma separation. DOE will continue to support development of another uranium enrichment technology, gas centrifugation. By or around 1990, the most promising gas centrifuge technique will be compared

Rawls

1982-01-01

18

SEPARATION OF URANIUM, PLUTONIUM AND FISSION PRODUCTS  

DOEpatents

The separation of uranium and plutonium from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in nitric acid to provide an aqueous solution 3N in nitric acid. The fission products of the solution are extruded by treating the solution with dibutyl carbitol substantially 1.8N in nitric acid. The organic solvent phase is separated and neutralized with ammonium hydroxide and the plutonium reduced with hydroxylamine base to the trivalent state. Treatment of the mixture with saturated ammonium nitrate extracts the reduced plutonium and leaves the uranium in the organic solvent.

Nicholls, C.M.; Wells, I.; Spence, R.

1959-10-13

19

Separation of zirconium and uranium. [Patent application  

SciTech Connect

This invention relates to separation and recovery of zirconium from aqueous solutions containing zirconium and uranium. Separation of zirconium from uranium is, however, difficult since the uranium tends to accompany the zirconium in the solvent extraction and stripping steps. It is therefore desirable, and an object of the invention, to provide a simple and economical way of removing a major portion of the zirconium from the zirconium and uranium-containing strip solutions, with minimal removal of uranium. It has now been found, according to the present invention, that such a removal of zirconium may be accomplished by means of a process involving precipitation of zirconium from such zirconium and uranium-containing feed solutions by means of tartaric acid or a tartrate.

Henry, H.G.

1981-05-27

20

Method of separating iron from uranium  

Microsoft Academic Search

In uranium recovery by solvent extraction processes, uranium is separated from iron in an organic extract by stripping the extract with a dilute aqueous solution containing carbonate ions, hydroxyl ions, and ammonium or alkali metal ions. The iron precipitates during stripping as FeâOâ.nHâO which is filtered off. The uranium is then precipitated from the filtrate as UO3.2H2O by steam stripping

Chiang

1981-01-01

21

Method of separating molybdenum from uranium  

Microsoft Academic Search

A method is disclosed for separating uranium from molybdenum in an aqueous solution. The pH of the solution is lowered to about 1 to about 4 using an inorganic acid such as hydrochloric acid. The carbon dioxide is then removed from the solution which can be done by aeration. The pH of the solution is raised to about 9 in

T. J. Crosssley; T. P. Zinge

1983-01-01

22

Aerodynamic isotope separation processes for uranium enrichment: process requirements  

Microsoft Academic Search

The pressing need for enriched uranium to fuel nuclear power reactors, requiring that as many as ten large uranium isotope separation plants be built during the next twenty years, has inspired an increase of interest in isotope separation processes for uranium enrichment. Aerodynamic isotope separation processes have been prominently mentioned along with the gas centrifuge process and the laser isotope

Malling; G. F. Von Halle

1976-01-01

23

SEPARATION OF PLUTONIUM FROM URANIUM AND FISSION PRODUCTS  

DOEpatents

A chromatographic adsorption process is presented for the separation of plutonium from other fission products formed by the irradiation of uranium. The plutonium and the lighter element fission products are adsorbed on a sulfonated phenol-formaldehyde resin bed from a nitric acid solution containing the dissolved uranium. Successive washes of sulfuric, phosphoric, and nitric acids remove the bulk of the fission products, then an eluate of dilute phosphoric and nitric acids removes the remaining plutonium and fission products. The plutonium is selectively removed by passing this solution through zirconium phosphate, from which the plutonium is dissolved with nitric acid. This process provides a convenient and efficient means for isolating plutonium.

Boyd, G.E.; Adamson, A.W.; Schubert, J.; Russell, E.R.

1958-10-01

24

Separation of hydrogen isotopes with uranium hydride  

Microsoft Academic Search

The isotope effect on the decomposition behavior of uranium hydride is examined, since the separation of hydrogen isotopes is one of the most important processes in fission and fusion power generating systems. The decomposition equilibrium pressure is measured for UH3, UD3, and UH(1.5)D(1.5) in the temperature range of 500-700 K; the decomposition pressure of UD3 is higher than that of

S. Imoto; T. Tanabe; K. Utsunomiya

1981-01-01

25

Analysis of uranium isotope separation by redox chromatography  

SciTech Connect

Uranium isotope separation by redox chromatography is analytically studied. The periodic withdrawal of products and tails and the introduction of natural feed are simulated on the assumption of a square cascade for a uranium adsorption band. The influences on the separative power and the lead time until product withdrawal are investigated by varying the magnitude of the isotope separation factor, uranium band length, tails concentration, and so on. Simulating calculations indicate that using ion-exchange resins to achieve uranium isotope separation requires a very long lead time for the production of highly enriched uranium.

Fujine, S.; Naruse, Y.; Shiba, K.

1983-09-01

26

SEPARATION OF PLUTONIUM VALUES FROM URANIUM AND FISSION PRODUCT VALUES  

DOEpatents

Separation of plutonium present in small amounts from neutron irradiated uranium by making use of the phenomenon of chemisorption is described. Plutonium in the tetravalent state is chemically absorbed on a fluoride in solid form. The steps for the separation comprise dissolving the irradiated uranium in nitric acid, oxidizing the plutonium in the resulting solution to the hexavalent state, adding to the solution a soluble calcium salt which by the common ion effect inhibits dissolution of the fluoride by the solution, passing the solution through a bed or column of subdivided calcium fluoride which has been sintered to about 8OO deg C to remove the chemisorbable fission products, reducing the plutonium in the solution thus obtained to the tetravalent state, and again passing the solution through a similar bed or column of calcium fluoride to selectively absorb the plutonium, which may then be recovered by treating the calcium fluoride with a solution of ammonium oxalate.

Maddock, A.G.; Booth, A.H.

1960-09-13

27

Separation of hydrogen isotopes with uranium hydride  

NASA Astrophysics Data System (ADS)

The isotope effect on the decomposition behavior of uranium hydride is examined, since the separation of hydrogen isotopes is one of the most important processes in fission and fusion power generating systems. The decomposition equilibrium pressure is measured for UH3, UD3, and UH(1.5)D(1.5) in the temperature range of 500-700 K; the decomposition pressure of UD3 is higher than that of UH3, and UH(1.5)D(1.5) shows an intermediate decomposition pressure. The enthalpy and entropy formations are obtained and they are in good agreement with those determined by a calorimetric study. When the reaction reaches the point of equilibrium, deuterium is enriched in the gas phase, and the separation factor is approximately 1.3. Experiments on deuterium enrichment, made with a small cascade, also show a separation factor of about 1.3. A thermodynamic model for the case where the mixed hydride is the regular solution, is used, and it is shown that the separation factor is larger for gas mixtures with a high D/H ratio at higher temperatures and for those with a low D/H ratio at lower temperatures.

Imoto, S.; Tanabe, T.; Utsunomiya, K.

28

Magnetic separation of uranium from magnesium fluoride  

SciTech Connect

The attraction or repulsion of particles by a magnetic gradient, based on the respective susceptibilities, provides the basis for physical separation of particles that are comprised predominantly of uranium from those that are predominantly magnesium fluoride (MgF/sub 2/). To determine the effectiveness of this approach, a bench-scale magnetic separator from the S.G. Frantz Co., Inc. was used. In the Frantz Model L-1, particles are fed through a funnel onto a vibration tray and through a magnetic field. The specific design of the Frantz magnet causes the magnetic field strength to vary along the width of the magnet, setting up a gradient. The tray in the magnetic field is split at a point about half way down its length so that the separated material does not recombine. A schematic is presented of Frantz Model L-1 CN - the same magnet configured for high gradient magnetic separation of liquid-suspended particles. Here different pole pieces create a uniform magnetic field, and stainless steel wood in the canister between the pole pieces creates the high gradient. 1 ref., 6 figs., 2 tabs.

Hoegler, J.M.

1987-01-01

29

Tributyl-phosphate-impregnated sorbents for plutonium-uranium separations  

SciTech Connect

Bayer AG Lewatit OC-1023, a macroporous sorbent impregnated with tributyl phosphate (TBP), was evaluated for the separation of uranium and plutonium from mixed actinide residues. The sorbent was tested for uranium breakthrough capacity, plutonium washing, and uranium elution behavior. TBP-impregnated Amberlite XAD-4 was compared to the Lewatit OC-1023.

Alford, C.E.; Navratil, J.D.

1986-03-24

30

Uranium isotope separation from 1941 to the present  

Microsoft Academic Search

Uranium isotope separation was the key development for the preparation of highly enriched isotopes in general and thus became the seed for target development and preparation for nuclear and applied physics.In 1941 (year of birth of the author) large-scale development for uranium isotope separation was started after the US authorities were warned that NAZI Germany had started its program for

Peter Maier-Komor

2010-01-01

31

Separation of rubidium from irradiated aluminum-encapsulated uranium  

SciTech Connect

A procedure was developed for separating rubidium from irradiated aluminum encapsulated uranium. The separations procedure produces a final ultra-high purity RbCl product for subsequent high performance mass spectrometric analysis. The procedure involves first removing most of the macro-components and fission products by strong base anion exchange using, first, concentrated HCl, then oxalic acid media and second, selectively separating rubidium from alkaline-earth ions and other alkali-metal ions, including cesium, using Bio-Rex-40 cation-exchange resin. The resultant RbCl is then put through a final vacuum sublimation step. Ultra-pure reagents and specially clean glassware are used throughout the procedure to minimize contamination by naturally-occurring rubidium.

Horwitz, E.P.; Schmitz, F.J.; Rokop, D.J.

1982-01-01

32

Separation of uranium isotopes by chemical exchange  

DOEpatents

A chemical exchange method is provided for separating /sup 235/U from / sup 238/U comprising contacting a first phase containing UF/sub 6/ with a second phase containing a compound selected from the group consisting of NOUF/sub 6/, NOUF/sub 7/, and NO/sub 2/UF/sub 7/ until the U Fsub 6/ in the first phase becomes enriched in the /sup 235/U isotope. (Official Gazette)

Ogle, P.R. Jr.

1974-02-26

33

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

34

Separation and Recovery of Uranium and Plutonium from Oxalate Supernatant  

Microsoft Academic Search

The separation of uranium and plutonium from oxalate supernatant, obtained after precipitating plutonium oxalate, containing ~10 g\\/l uranium and 30–100 mg\\/l plutonium in 3M HNO3 and 0.10–0.18M oxalic acid solution has been carried out. In one extraction step with 30% TBP in dodecane: ~92% of uranium and ~7% of Pu is extracted. The raffinate containing the remaining U and Pu

K. M. Michael; G. H. Rizvi; J. N. Mathur; A. Ramanujam

2000-01-01

35

PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM  

Microsoft Academic Search

Processes are described for preparing plutonium, particularly processes ; of separating plutonium from uranium and fission products in neutron-irradiated ; uraniumcontaining matter. Specifically, plutonium solutions containing uranium, ; fission products and other impurities are contacted with reducing agents such as ; sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ; ferrous ion whereby the plutoninm is reduced to

R. E. Connick; J. W. Gofman; G. C. Pimentel

1959-01-01

36

Selective Extraction of Uranium from Liquid or Supercritical Carbon Dioxide  

SciTech Connect

Current liquid-liquid extraction processes used in recycling irradiated nuclear fuel rely on (1) strong nitric acid to dissolve uranium oxide fuel, and (2) the use of aliphatic hydrocarbons as a diluent in formulating the solvent used to extract uranium. The nitric acid dissolution process is not selective. It dissolves virtually the entire fuel meat which complicates the uranium extraction process. In addition, a solvent washing process is used to remove TBP degradation products, which adds complexity to the recycling plant and increases the overall plant footprint and cost. A liquid or supercritical carbon dioxide (l/sc -CO2) system was designed to mitigate these problems. Indeed, TBP nitric acid complexes are highly soluble in l/sc -CO2 and are capable of extracting uranium directly from UO2, UO3 and U3O8 powders. This eliminates the need for total acid dissolution of the irradiated fuel. Furthermore, since CO2 is easily recycled by evaporation at room temperature and pressure, it eliminates the complex solvent washing process. In this report, we demonstrate: (1) A reprocessing scheme starting with the selective extraction of uranium from solid uranium oxides into a TBP-HNO3 loaded Sc-CO2 phase, (2) Back extraction of uranium into an aqueous phase, and (3) Conversion of recovered purified uranium into uranium oxide. The purified uranium product from step 3 can be disposed of as low level waste, or mixed with enriched uranium for use in a reactor for another fuel cycle. After an introduction on the concept and properties of supercritical fluids, we first report the characterization of the different oxides used for this project. Our extraction system and our online monitoring capability using UV-Vis absorbance spectroscopy directly in sc-CO2 is then presented. Next, the uranium extraction efficiencies and kinetics is demonstrated for different oxides and under different physical and chemical conditions: l/sc -CO2 pressure and temperature, TBP/HNO3 complex used, reductant or complexant used for selectivity, and ionic liquids used as supportive media. To complete the extraction and recovery cycle, we then demonstrate uranium back extraction from the TBP loaded sc-CO2 phase into an aqueous phase and the characterization of the uranium complex formed at the end of this process. Another aspect of this project was to limit proliferation risks by either co-extracting uranium and plutonium, or by leaving plutonium behind by selectively extracting uranium. We report that the former is easily achieved, since plutonium is in the tetravalent or hexavalent oxidation state in the oxidizing environment created by the TBP-nitric acid complex, and is therefore co-extracted. The latter is more challenging, as a reductant or complexant to plutonium has to be used to selectively extract uranium. After undertaking experiments on different reducing or complexing systems (e.g., AcetoHydroxamic Acid (AHA), Fe(II), ascorbic acid), oxalic acid was chosen as it can complex tetravalent actinides (Pu, Np, Th) in the aqueous phase while allowing the extraction of hexavalent uranium in the sc-CO2 phase. Finally, we show results using an alternative media to commonly used aqueous phases: ionic liquids. We show the dissolution of uranium in ionic liquids and its extraction using sc-CO2 with and without the presence of AHA. The possible separation of trivalent actinides from uranium is also demonstrated in ionic liquids using neodymium as a surrogate and diglycolamides as the extractant.

Farawila, Anne F.; O'Hara, Matthew J.; Wai, Chien M.; Taylor, Harry Z.; Liao, Yu-Jung

2012-07-31

37

New separation process for neptunium, plutonium, and uranium using butyraldehydes as reductants in reprocessing  

SciTech Connect

A new neptunium, plutonium, and uranium separation process using n- and iso-butyraldehydes as reductants for Np(VI) and Pu(IV), respectively, is described for nuclear fuel reprocessing. A kinetics study and a chemical flow sheet study are conducted to develop the selective separation process for neptunium, plutonium, and uranium. In the kinetics study, it is found that n-butyraldehyde reduces Np(VI) to Np(V) in the Purex solution but does not reduce Pu(IV) and U(VI), and iso-butyraldehyde reduces Np(VI) and Pu(IV) but does not reduce U(VI). Based on these results, a new process to separate neptunium, plutonium, and uranium selectively is proposed. The process consists mainly of three steps: the codecontamination step, the neptunium separation step [in which Np(VI) extracted by a solvent of 30% tri-n-butyl phosphate (TBP)/n-dodecane together with Pu(IV) and U(VI) is reduced to Np(V) by n-butyraldehyde and is back-extracted from the solvent], and the uranium/plutonium (U/Pu) partition step using iso-butyraldehyde as a Pu(IV) reductant. In the chemical flow sheet study, the effectiveness of the separation process is demonstrated by the use of miniature mixer-settlers. In the neptunium separation step, [approximately]99.98% of the neptunium extracted by the 30% TBP/n-dodecane solvent along with U(VI) in the uranium/neptunium coextraction step is reduced by n-butyraldehyde and separated from the uranium stream. In the U/Pu partition step, >99% of the plutonium is reduced by iso-butyraldehyde and separated from the uranium stream.

Uchiyama, Gunzo; Fujine, Sachio; Hotoku, Shinobu; Maeda, Mitsuru (Japan Atomic Energy Research Inst., Ibaraki (Japan))

1993-06-01

38

Uranium accountancy in Atomic Vapor Laser Isotope Separation  

SciTech Connect

The AVLIS program pioneers the large scale industrial application of lasers to produce low cost enriched uranium fuel for light water reactors. In the process developed at Lawrence Livermore National Laboratory, normal uranium is vaporized by an electron beam, and a precisely tuned laser beam selectively photo-ionizes the uranium-235 isotopes. These ions are moved in an electromagnetic field to be condensed on the product collector. All other uranium isotopes remain uncharged and pass through the collector section to condense as tails. Tracking the three types of uranium through the process presents special problems in accountancy. After demonstration runs, the uranium on the collector was analyzed for isotopic content by Battelle Pacific Northwest Laboratory. Their results were checked at LLNL by analysis of parallel samples. The differences in isotopic composition as reported by the two laboratories were not significant.

Carver, R.D.

1986-01-01

39

SEPARATION OF URANIUM FROM THORIUM BY LIQUID METAL EXTRACTION THORIUM RECOVERY AND FISSION PRODUCT DISTRIBUTION  

Microsoft Academic Search

Additional results were obtained on the small-scale separation of ; uranium from thorium by molten magnesium extraction. This process is aimed at ; the separation and recovery of uranium and thorium from a thorium breeder blanket. ; On dissolution of a thorium-uranium alloy in molten magnesium, 90 to 95% of the ; uranium introduced was recovered as a uranium -thorium

J. D. Chilton; L. A. Hanson; E. W. Murbach; F. W. Dodge

1962-01-01

40

Uranium isotope separation from 1941 to the present  

NASA Astrophysics Data System (ADS)

Uranium isotope separation was the key development for the preparation of highly enriched isotopes in general and thus became the seed for target development and preparation for nuclear and applied physics. In 1941 (year of birth of the author) large-scale development for uranium isotope separation was started after the US authorities were warned that NAZI Germany had started its program for enrichment of uranium and might have confiscated all uranium and uranium mines in their sphere of influence. Within the framework of the Manhattan Projects the first electromagnetic mass separators (Calutrons) were installed and further developed for high throughput. The military aim of the Navy Department was to develop nuclear propulsion for submarines with practically unlimited range. Parallel to this the army worked on the development of the atomic bomb. Also in 1941 plutonium was discovered and the production of 239Pu was included into the atomic bomb program. 235U enrichment starting with natural uranium was performed in two steps with different techniques of mass separation in Oak Ridge. The first step was gas diffusion which was limited to low enrichment. The second step for high enrichment was performed with electromagnetic mass spectrometers (Calutrons). The theory for the much more effective enrichment with centrifugal separation was developed also during the Second World War, but technical problems e.g. development of high speed ball and needle bearings could not be solved before the end of the war. Spying accelerated the development of uranium separation in the Soviet Union, but also later in China, India, Pakistan, Iran and Iraq. In this paper, the physical and chemical procedures are outlined which lead to the success of the project. Some security aspects and Non-Proliferation measures are discussed.

Maier-Komor, Peter

2010-02-01

41

PROCESS OF SEPARATING PLUTONIUM FROM URANIUM  

DOEpatents

A process is presented for recovering plutonium values from aqueous solutions. It comprises forming a uranous hydroxide precipitate in such a plutonium bearing solution, at a pH of at least 5. The plutonium values are precipitated with and carried by the uranium hydroxide. The carrier precipitate is then redissolved in acid solution and the pH is adjusted to about 2.5, causing precipitation of the uranous hydroxide but leaving the still soluble plutonium values in solution.

Brown, H.S.; Hill, O.F.

1958-09-01

42

Uranium-preextraction in zirconium\\/hafnium separations processs  

Microsoft Academic Search

This patent describes an improvement in a process for recovering zirconium values from uranium containing zircon ore. The process comprising a fluidized bed carbochlorination of the zircon ore at 800°--1250° C., producing a relatively impure, hafnium-containing zirconium tetrachloride stream and by-product silicon tetrachloride, which silicon tetrachloride by-product is separated by differential condensation, and wherein uranium chloride is volatilized at the

Feuling

1990-01-01

43

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

44

Ion Exchange Separation and Mass Spectrometric Analysis of Uranium for Solutions Containing Plutonium.  

National Technical Information Service (NTIS)

An ion exchange technique separates plutonium from uranium using Dowex-1 resin and a methanol--HCl plutonium elutriant. The method is applicable to both trace uranium determination and uranium isotopic distribution analysis by mass spectrometry. Distribut...

K. C. McBride

1975-01-01

45

Large-Scale Physical Separation of Depleted Uranium from Soil.  

National Technical Information Service (NTIS)

Dry physical separation processes were tested at large-pilot scale (1,000 kg soil batches) at Yuma Proving Ground (YPG) to evaluate this technique for removal of depleted uranium (DU) metal from soil. Two sample locations, the Catch Box and the Buried DU ...

C. Griggs J. Ballard M. Wynter S. L. Larson V. F. Medina

2012-01-01

46

A novel extractant-impregnated resin containing carminic acid for selective separation and pre-concentration of uranium(VI) and thorium(IV)  

Microsoft Academic Search

The present work proposes the use of a novel extractant-impregnated resin (EIR) as an adsorbent in trace separation and pre-concentration of U(VI) and Th(IV) ions. The new EIR was prepared by impregnating carminic acid onto Amberlite XAD-16 resin beads. The morphology of new EIR was studied by BET surface area measurements and SEM micrographs. A column packed with CA\\/XAD-16 was

Ahmad Hosseini-Bandegharaei; Mohammad Saeid Hosseini; Yousef Jalalabadi; Mehdi Nedaie; Masoud Sarwghadi; Akram Taherian; Esmat Hosseini

2011-01-01

47

SEPARATION OF URANIUM AND PLUTONIUM OXIDES  

DOEpatents

ABS>A method of separating a mixture of UO/sub 2/ and PuO/sub 2/ is given which comprises immersing the mixture in a fused NaCl-KCl bath, chlorinating with chlorine or phosgene, and preferentially electrolytically or chemically reducing the UO/sub 2/Cl/sub 2/ so produced to UO/sub 2/ and filtering it out. (AEC)

Benedict, G.E.; Lyon, W.L.

1961-12-01

48

Selective Recovery of Enriched Uranium from Inorganic Wastes  

Microsoft Academic Search

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

Kimura

2003-01-01

49

Bio-/Photo-Chemical Separation and Recovery of Uranium  

SciTech Connect

Citric acid forms bidentate, tridentate, binuclear or polynuclear species with transition metals and actinides. Biodegradation of metal citrate complexes is influenced by the type of complex formed with metal ions. While bidentate complexes are readily biodegraded, tridentate, binuclear and polynuclear species are recalcitrant. Likewise certain transition metals and actinides are photochemically active in the presence of organic acids. Although the uranyl citrate complex is not biodegraded, in the presence of visible light it undergoes photochemical oxidation/reduction reactions which result in the precipitation of uranium as UO{sub 3} {center_dot} H{sub 2}O. Consequently, we developed a process where uranium is extracted from contaminated soils and wastes by citric acid. The citric-acid extract is subjected to biodegradation to recover the toxic metals, whereas uranyl citrate which is recalcitrant remains in solution. Photochemical degradation of the uranium citrate complex resulted in the precipitation of uranium. Thus the toxic metals and uranium in mixed waste are recovered in separate fractions for recycling or for disposal. The use of naturally-occurring compounds and the combined chemical and microbiological treatment process is more efficient than present methods and should result in considerable savings in cost.

Francis,A.J.; Dodge, C.J.

2008-03-12

50

Effects of Separation Processes on Minor Uranium Isotopes in Enrichment Cascades  

Microsoft Academic Search

In natural uranium, there are trace amounts of the “minor isotope” U in addition to the more abundant U and U. Uranium irradiated in a reactor and separated from the spent reactor fuel by reprocessing will contain additional minor isotopes. In uranium enrichment, cascades of separating units are tuned to produce the desired level of the isotope U, but the

HOUSTON G. WOOD

2008-01-01

51

Uranium-preextraction in zirconium/hafnium separations processs  

SciTech Connect

This patent describes an improvement in a process for recovering zirconium values from uranium containing zircon ore. The process comprising a fluidized bed carbochlorination of the zircon ore at 800{degrees}--1250{degrees} C., producing a relatively impure, hafnium-containing zirconium tetrachloride stream and by-product silicon tetrachloride, which silicon tetrachloride by-product is separated by differential condensation, and wherein uranium chloride is volatilized at the ore chlorinator temperature and follows as an impurity in the zirconium-hafnium tetrachloride stream, mixing the zirconium-hafnium tetrachloride with water to produce a zirconium-hafnium oxychloride solution, and removing iron impurities by liquid--liquid iron extraction with a methyl isobutyl ketone extractant.

Feuling, R.J.

1990-04-03

52

PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM  

DOEpatents

Processes are described for preparing plutonium, particularly processes of separating plutonium from uranium and fission products in neutron-irradiated uraniumcontaining matter. Specifically, plutonium solutions containing uranium, fission products and other impurities are contacted with reducing agents such as sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ferrous ion whereby the plutoninm is reduced to its fluoride-insoluble state. The reduced plutonium is then carried out of solution by precipitating niobic oxide therein. Uranium and certain fission products remain behind in the solution. Certain other fission products precipitate along with the plutonium. Subsequently, the plutonium and fission product precipitates are redissolved, and the solution is oxidized with oxidizing agents such as chlorine, peroxydisulfate ion in the presence of silver ion, permanganate ion, dichromate ion, ceric ion, and a bromate ion, whereby plutonium is oxidized to the fluoride-soluble state. The oxidized solution is once again treated with niobic oxide, thus precipitating the contamirant fission products along with the niobic oxide while the oxidized plutonium remains in solution. Plutonium is then recovered from the decontaminated solution.

Connick, R.E.; Gofman, J.W.; Pimentel, G.C.

1959-11-10

53

METHOD OF SEPARATING FISSION PRODUCTS FROM FUSED BISMUTH-CONTAINING URANIUM  

DOEpatents

A process is described for removing metal selectively from liquid metal compositions. The method effects separation of flssion product metals selectively from dilute solution in fused bismuth, which contains uraniunn in solution without removal of more than 1% of the uranium. The process comprises contacting the fused bismuth with a fused salt composition consisting of sodium, potassium and lithium chlorides, adding to fused bismuth and molten salt a quantity of bismuth chloride which is stoichiometrically required to convert the flssion product metals to be removed to their chlorides which are more stable in the fused salt than in the molten metal and are, therefore, preferentially taken up in the fused salt phase.

Wiswall, R.H.

1958-06-24

54

Separation of plutonium from uranium using reactive chemistry in a bandpass reaction cell of an inductively coupled plasma mass spectrometer.  

PubMed

Oxygen and ammonia were evaluated as reaction gases for the chemical separation between uranium and plutonium in the bandpass reaction cell or dynamic reaction cell (DRC) of the ELAN DRC II mass spectrometer. Both uranium and plutonium demonstrated similar reactivity with oxygen giving rise to corresponding oxides. At the same time, remarkable selectivity in the reaction with ammonia was observed. While uranium was rapidly converted into UNH 2+ and UN2H 4+, plutonium remained unreactive in the DRC pressurized with ammonia. This difference in the reactivity allowed the determination of plutonium isotopes in urine and water samples containing excess uranium without preceding separation procedure. Detection limits of 0.245, 0.092, 0.270 and 0.237 ng L(-1) were obtained for 238Pu, 239Pu, 240Pu and 242Pu, respectively, in urine spiked with 10 microg L(-1) of U. PMID:15197531

Vais, Vladimir; Li, Chunsheng; Cornett, Jack

2004-06-10

55

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

56

Selective removal of dissolved uranium in drinking water by nanofiltration.  

PubMed

A procedure for the selective removal of uranium traces dissolved in drinking water has been studied. Plate module membrane filtration equipment was operated to evaluate the performance and selectivity of three different nanofiltration flat-sheet membranes. Experiments were carried out using various commercial mineral waters with distinct physicochemical compositions. The membranes were first discriminating by their ability to reject uranium in the presence of the main cations found in mineral waters, using a 2 mg L(-1) (2000 ppb) concentration of uranium. The rejection of U(VI) was dependent on the uranyl speciation and the ionic strength. Second, removal of uranium traces (0.02 mg L(-1), 20 ppb) was performed using the nanofiltration membrane showing the highest selectivity for uranium toward alkaline and alkaline-earth ions. The results showed a high performance of the nanofiltration membrane, Osmonics DL, for selective uranium rejection at low pressure (1 bar), illustrating the advantage of nanofiltration for the selective removal of uranium from drinking water. PMID:17888486

Favre-Réguillon, A; Lebuzit, G; Murat, D; Foos, J; Mansour, C; Draye, M

2007-09-07

57

Separation of uranium from lanthanum in molecular and ionic organic liquids  

Microsoft Academic Search

We have investigated the separation of uranium from lanthanum in two molecular organic liquids (sulfolane, TMSO2; ethylene carbonate, EC) and in one organic ionic melt: ethylammonium nitrate (EAN). A separation is achieved by chemical oxidation and precipitation of oxides in TMSO2; in this medium, the part of uranium remaining in solution may be recovered by an electrochemical reduction. In EAN,

L. Lopes; L. Martinot; C. Michaux

1994-01-01

58

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

59

Investigation of uranium binding forms in selected German mineral waters.  

PubMed

Cryogenic time-resolved laser-induced fluorescence spectroscopy was successfully used to identify uranium binding forms in selected German mineral waters of extremely low uranium concentrations (<2.0 ?g/L). The measurements were performed at a low temperature of 153 K. The spectroscopic data showed a prevalence of aquatic species Ca2UO2(CO3)3 in all investigated waters, while other uranyl-carbonate complexes, viz, UO2CO3(aq) and UO2(CO3)2 (2-), only existed as minor species. The pH value, alkalinity (CO3 (2-)), and the main water inorganic constituents, specifically the Ca(2+) concentration, showed a clear influence on uranium speciation. Speciation modeling was performed using the most recent thermodynamic data for aqueous complexes of uranium. The modeling results for the main uranium binding form in the investigated waters indicated a good agreement with the spectroscopy measurements. PMID:23702572

Osman, Alfatih A A; Geipel, Gerhard; Bernhard, Gert; Worch, Eckhard

2013-05-24

60

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

61

Separation of uranium from technetium in recovery of spent nuclear fuel  

DOEpatents

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, David J. (Knoxville, TN); McTaggart, Donald R. (Knoxville, TN)

1984-01-01

62

Separation of uranium from technetium in recovery of spent nuclear fuel  

DOEpatents

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.

1983-08-31

63

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

2012-06-12

64

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

65

ARSENATE CARRIER PRECIPITATION METHOD OF SEPARATING PLUTONIUM FROM NEUTRON IRRADIATED URANIUM AND RADIOACTIVE FISSION PRODUCTS  

DOEpatents

A process is described for precipitating Pu from an aqueous solution as the arsenate, either per se or on a bismuth arsenate carrier, whereby a separation from uranium and fission products, if present in solution, is accomplished.

Thompson, S.G.; Miller, D.R.; James, R.A.

1961-06-20

66

Ligand-grafted biomaterials for adsorptive separations of uranium in solution  

SciTech Connect

Many organic molecules, particularly biologicals, contain functional groups (ligands) that actively interact with metal ions in solution by adsorption, ion exchange, or chelation/coordination/complexation. Water-soluble organics have limitations as reagents for metal-ion separations from aqueous solutions. However, if the ligand molecule(s) are grafted on to an insoluble matrix, the resulting ligand(s)-containing product becomes useful for separations applications related to metal recovery or remediation. It was discovered that biomolecules containing a primary amino group, secondary amino group, or hydroxyl group could be grafted into a polyurethane polymeric network via in situ polymerization reactions. With carboxyl groups, grafted material showed good selectivity among a group of divalent metal cations, and a uranium-binding capacity of more than 10 mg/g of polymer. The material can be regenerated by sodium bicarbonate or sodium carbonate solution and reused. Data from a stirred-tank reactor showed fast uranium-binding kinetics, and breakthrough-elution studies with a packed-column reactor indicated promising process behavior.

Hu, M.Z.C.; Reeves, M.

1999-11-01

67

Uranium isotope separation by continuous anion exchange chromatography  

Microsoft Academic Search

This paper reports a process for producing nuclear quality Uranium 235 (U²³⁵) from a substantially impure feed stock containing a mixture of uranium isotopes, including U²³⁵, forming a stationary phase from an anion exchange resin in the annulus of a rotating annular chromatograph; feeding the feed stock to the stationary phase to load less than 10% of the stationary phase;

T. S. Snyder; H. M. Ferrari

1992-01-01

68

Separation and recovery of molybdenum values from uranium process waste  

Microsoft Academic Search

A method is described of recovering molybdenum and uranium values from a process waste generated from the production of nuclear-grade uranium hexafluoride which consists of: (a) hydrolysing the process waste which contains UFâ, MoFâ and MoOFâ in an aqueous solution containing ammonium carbonate and ammonium hydroxide thereby forming ammonium uranyl carbonate; (b) digesting while maintaining a pH > 9, the

D. Nalewajek; L. E. McCurry; D. J. Friedland; R. E. Eibeck

1986-01-01

69

Separation of uranium and dibutyl phosphate contained in 30 vol % tributyl phosphate solvents  

SciTech Connect

A number of solid sorbents were tested for the removal of uranium and dibutyl phosphate (DBP) from 30 vol % tributyl phosphate (TBP) solvent. The removal was required to result in separation of the uranium from the DBP with a clean uranium product. The preferred mode of operation was to remove the DBP, leaving the uranium in the cleaned solvent for recycle. A method for removal of DBP from the solvent while allowing the uranium to remain in the solvent was not found. Both cation resins and diethylene triamine pentaacetic acid (DTPA) deposited on glass beads preferentially removed the uranium, leaving the DBP in the solvent. The DBP could then be readily removed by a number of simple treatments, and the uranium could be recovered by elution with acidified TBP. Both hydroxide-form, anion-exchange resins and activated alumina (used with dry solvent) removed uranium and DBP. It is possible that the DBP and uranium could be separately eluted from these sorbents, but it was not successfully tested. 4 refs., 17 figs., 1 tab.

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

1986-07-01

70

Extraction and separation of uranium and lead with liquid anion-exchangers.  

PubMed

A method is proposed for the extraction and separation of microgram amounts of uranium(VI) and lead(II) from sodium salicylate solution with high molecular-weight amines such as Aliquat 336, TOA, TIOA, Amberlite LA-1 or Amberlite LA-2 dissolved in xylene. From a critical study of pH, salicylate concentration, amine concentration, diluent and period of equilibration, the optimum conditions were identified. The method permits separation of uranium and lead from binary mixtures with metal ions commonly associated with them, the determination of uranium, and of lead in air samples. PMID:18965132

Sundaramurthi, N M; Shinde, V M

1991-02-01

71

Influence of process variables in the high gradient separation of uranium ores  

SciTech Connect

Some uranium minerals are paramagnetic and hence are amenable to concentration by high gradient magnetic separation (HGMS). This paper describes effects of the HGMS parameters--pulp velocity, field strength, matrix loading, and magnetic field gradient--on the product recovery and grade. Unsatisfactory separation of uranium minerals by HGMS is related to ore-specific properties, such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix, and interference of fine-sized slimes. Experimental techniques to identify and resolve some of these problems are outlined.

Malghan, S.G.; Van Dillen, J.P.

1983-12-01

72

Selection of lixiviants for in situ uranium leaching. Information circular  

Microsoft Academic Search

This Bureau of Mines publication provides information to assist in selecting a lixiviant (leach solution) for in situ uranium leaching. The cost, advantages, and disadvantages of lixiviants currently used and proposed are presented. Laboratory and field tests are described, and applications of geochemical models are discussed. Environmental, economic, and technical factors should all be considered. Satisfying environmental regulations on restoring

D. R. Tweeton; K. A. Peterson

1981-01-01

73

SASSE Modeling of a Uranium/Molybdenum Separation Flowsheet.  

National Technical Information Service (NTIS)

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% 23...

J. E. Laurinat

2007-01-01

74

Evaluating ion exchange resin efficiency and oxidative capacity for the separation of uranium(IV) and uranium(VI)  

PubMed Central

Background Previously described methods to separate dissolved U(IV) from dissolved U(VI) under acidic anoxic conditions prior to laboratory analysis were ineffective with materials currently available commercially. Three strong anion exchange resins were examined for their efficiency in separating, recovering, and preserving both redox states during separation. Results Under oxic conditions, recovery of U(VI) from three exchange resins (Bio-Rad AG® 1x8 Poly-Prep® prefilled columns, Bio-Rad AG® 1x8 powder, and Dowex® 1x8 powder) ranged from 72% to 100% depending on the dosed mass, eluent volume, and resin selected. Dowex® 1x8 resin was the only resin found to provide 100% recovery of U(VI) with fewer than 5 bed volumes of eluent. Under anoxic conditions, all three resins oxidized U(IV) in aqueous solutions with relatively low U(IV) concentrations (<3x10-6 M). Resin-induced oxidation was observed visually using a leuco dye, safranin-o. Oxidants associated with the resin were irreversibly reduced by the addition of Ti(III). After anoxic resin pre-treatment, a series of U(IV)/U(VI) mixtures at micro-molar levels were prepared and separated using the Dowex® 1x8 resin with 100% recovery of both U(IV) and U(VI) with no resin-induced changes in oxidation state. Conclusions Currently available anion exchange resins with apparently identical physical properties were found to have significantly different recoveries for hexavalent uranium at micro-molar concentrations. A novel qualitative technique was developed to visually assess oxidative capacities of anion exchange resins under acidic anoxic conditions. A protocol was developed for pre-treatment and use of currently available anion exchange resins to achieve quantitative separation of U(IV) and U(VI) in aqueous solutions with low U(IV) concentrations. This method can be applied to future work to quantitatively assess dissolved U(IV) and U(VI) concentrations in both laboratory and field samples.

2013-01-01

75

Selection and microstructures of high density uranium alloys  

SciTech Connect

Twelve uranium alloys have been selected for incorporation into very high density aluminum dispersion fuel plates for irradiation testing. These alloys are (nominally) U-10Mo, U-8Mo, U-6Mo, U-4Mo, U-9Nb-3Zr, U-6Nb-4Zr, U-5Nb-3Zr, U-2Mo-1Nb-1Zr, U-6Mo-1Pt, U-6Mo-0.6Ru, U-6Mo-0.6Si, and U-10Mo-0.05Sn. The rationale for selection of these fuels based on gamma phase stability, reports of good irradiation performance, and high uranium density will be discussed. The microstructures of these fuels were examined by SEM/EDS and XRD at three storage during the powder fabrication process. Microstructures of selected alloys are discussed.

Meyer, M.K.; Trybus, C.L.; Hofman, G.L.; Frank, S.M.; Wiencek, T.C.

1997-10-01

76

Separation and recovery of molybdenum values from uranium process waste  

SciTech Connect

A method is described of recovering molybdenum and uranium values from a process waste generated from the production of nuclear-grade uranium hexafluoride which consists of: (a) hydrolysing the process waste which contains UF/sub 6/, MoF/sub 6/ and MoOF/sub 4/ in an aqueous solution containing ammonium carbonate and ammonium hydroxide thereby forming ammonium uranyl carbonate; (b) digesting while maintaining a pH > 9, the resulting mother liquor at a temperature of about 60/sup 0/-80/sup 0/C. to evolve CO/sub 2/ and convert the ammonium uranyl carbonate to solid ammonium diuranate; (c) filtering, washing and drying the solid ammonium diuranate.

Nalewajek, D.; McCurry, L.E.; Friedland, D.J.; Eibeck, R.E.

1986-04-22

77

Uranium\\/technetium separation for the UREX process - synthesis and characterization of solid reprocessing forms  

Microsoft Academic Search

In the context of the demonstration of the UREX (uranium extraction) process, a separation of uranium and technetium using an anion exchange resin was performed on a simulant solution containing 98.95 g\\/L of ²³U and 130.2 mg\\/L of Tc. After sorption on the resin, TcO was eluted with NHOH, the eluting stream was treated, and the technetium converted to Tc

Frédéric Poineau; Julie Du Mazaubrun; Doris Ford; Jeffrey Fortner; Jeremy Kropf; G. W. Chinthaka Silva; Nicholas Smith; Kristy Long; Gordon Jarvinen; Kenneth R. Czerwinski

2008-01-01

78

Separation of adhered salt from uranium deposits generated in electro-refiner  

Microsoft Academic Search

It is important to increase a throughput of the salt removal process from uranium deposits which is generated on the solid\\u000a cathode of electro-refiner in pyroprocess. In this study, it was proposed to increase the throughput of the salt removal process\\u000a by the separation of the liquid salt prior to the distillation of the LiCl–KCl eutectic salt from the uranium

S. W. KwonK; K. M. Park; H. G. Ahn; H. S. Lee; J. G. Kim

2011-01-01

79

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

80

Uranium enrichment by the separation-nozzle process  

Microsoft Academic Search

The development of reliable manufacturing methods for commercial separation elements, the successful operation of separative stages, and extensive tests performed on plant components and auxiliary systems provide the basis for the construction of a separation-nozzle demonstration plant. The performance level achieved to date characterizes the process as reliable and economically feasible. In particular, it is generally ally accepted that comparatively

E. W. Becker; W. Bier; W. Ehrfeld; K. Schubert; R. Schütte; D. Seidel

1976-01-01

81

Ultratrace Uranium Fingerprinting with Isotope Selective Laser Ionization Spectrometry  

SciTech Connect

Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of Isotope Selective Laser Ionization Spectrometry (ISLIS) for ultratrace measurement of the minor isotopes 234U, 235U, and 236U with respect to 238U. Optical isotopic selectivity in three-step excitation with single-mode continuous wave lasers is capable of measuring the minor isotopes at relative abundances below 1 ppm, and is not limited by isobaric interferences such as 235UH+ during measurement of 236U. This relative abundance limit approaches the threshold for measurement of uranium minor isotopes with conventional mass spectrometry, typically 10-7, but without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 µg total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes.

Ziegler, Summer L.; Bushaw, Bruce A.

2008-08-01

82

Apparatus for the separation of gas mixtures, particularly the enrichment of a gas mixture in a component containing uranium 235  

Microsoft Academic Search

An apparatus for separating a gas mixture into a heavy component and a light component, especially for the enrichment of a gas mixture in uranium 235 in which the uranium isotopes are provided in the form of uranium hexafluoride, comprises a cascade of centrifuge stages each formed by a pair of spaced-apart disks surrounded by a housing and driven by

Gazda

1981-01-01

83

SEPARATING URANIUM CONTAINING SOLIDS SUSPENDED IN A LIQUID  

DOEpatents

A process is described for separating uraniumcontaining solids suspended in a liquid. It consists of adding to the liquid a wetting agent for the U- containing solids in an amount sufficient to form a separate liquid phase, the wetting agent having a density greater than the density of the liquid. Ethyl dibromoacetate is noted as one preferred wetting agent.

Creutz, E.C.; Wigner, E.P.

1958-05-01

84

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

85

Gas-Thermochromatography Separation Astatine. Relative Yield of Astatine Isotopes from Uranium.  

National Technical Information Service (NTIS)

Gas thermochromatographic method has been developed for fast separation and purification of astatine from uranium target irradiated with protons having an energy of 660 MeV. A mixture of oxygen and helium has been used as a reagent and carrier gas. A silv...

V. M. Vakhtel G. V. Vinel T. Vylov I. I. Gromova A. F. Novgorodov

1975-01-01

86

Behavior of the Minor Uranium Isotopes in Separation Cascades. Part V: Review and Appraisal.  

National Technical Information Service (NTIS)

Part V is the final chapter of the completion report for this study. The results of the calculations made to determine the behavior of the minor uranium isotopes ( exp 234 U and exp 236 U) in separation cascades and the results of the two plant tests made...

S. Blumkin E. Von Halle

1976-01-01

87

Development of a Ceramic-Lined Crucible for the Separation of Salt from Uranium  

NASA Astrophysics Data System (ADS)

As part of the spent fuel treatment program at the Idaho National Laboratory, alternate crucible materials are being developed for the processing of uranium and salt. The separation of salt (LiCl/KCl based) from uranium is performed in an inductively heated furnace capable of distillation under vacuum conditions. Historically, salt and uranium have been processed in graphite crucibles coated with a zirconia mold wash. Although the coated crucibles have performed adequately considering the reactive nature of salt and uranium at high temperature, the operations required for multiple use of the crucibles are quite labor intensive. Thus, an alternate ceramic-lined crucible has been developed to simplify remote operations. Two ceramic-lined crucibles have been tested using irradiated materials to verify their compatibility and determine an ultimate life cycle. Although minor process losses and crucible deterioration have occurred with the ceramic-lined crucibles, the overall performance of the crucibles has been adequate for the separation of salt during uranium processing.

Westphal, Brian R.; Marsden, K. C.; Price, J. C.

2009-12-01

88

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

89

Quantum criticality in selected uranium intermetallic and organometallic compounds  

NASA Astrophysics Data System (ADS)

My thesis presents the studies of the bulk properties of materials that exhibit unusual low-temperature properties due to the proximity of a quantum-critical point (QCP), for which long-range magnetic order can be suppressed to 0 K as a consequence of quantum fluctuations. A material can be tuned to the QCP by variation of a non-thermal control parameter such as hydrostatic pressure, magnetic field and chemical pressure/doping. Most of my experimental studies were performed at extreme conditions, such as high magnetic fields, low temperatures and/or high pressures. Two classes of materials were studied, namely uranium intermetallics and organometallics. The investigations on uranium intermetallics were done on compounds close to the edge of magnetism, i.e. the UCu4+xAl 8-x, UCuxAl5-x and UFe1-xNixAl compounds. Several of those compounds exhibit deviations from traditional Fermi-liquid theory and show non-Fermi liquid (NFL) scaling at low temperatures. Field-induced magnetic transitions were studied for some selected uranium compounds (UNiAl, UNiGa, UNiGe and UIrGe) as well. Furthermore, a study of organometallic quantum magnet (DTN: NiCl2-4SC(NH 2)2), which exhibits field-induced quantum criticality, is presented. In DTN, the magnetic-field induced polarization shows magneto-electric couplings between the antiferromagnetic Ni spins and the soft organic lattice.

Nasreen, Farzana

90

Selection of lixiviants for in situ uranium leaching. Information circular  

SciTech Connect

This Bureau of Mines publication provides information to assist in selecting a lixiviant (leach solution) for in situ uranium leaching. The cost, advantages, and disadvantages of lixiviants currently used and proposed are presented. Laboratory and field tests are described, and applications of geochemical models are discussed. Environmental, economic, and technical factors should all be considered. Satisfying environmental regulations on restoring groundwater quality is becoming an overriding factor, favoring sodium bicarbonate or dissolved carbon dioxide over ammonium carbonate. The cheapest lixiviant is dissolved carbon dioxide, but it is not effective in all deposits. Technical factors include clay swelling by sodium, acid consumption by calcite, and the low solubility of oxygen in shallow deposits.

Tweeton, D.R.; Peterson, K.A.

1981-10-01

91

Effects of selected physical and chemical parameters on uranium uptake by the bacterium Chryseomonas MGF-48  

Microsoft Academic Search

The effect of selected physical and chemical parameters, including media composition, uranium concentration, and metabolic inhibitors, on uranium uptake from aqueous solution by Chryseomonas sp. MGF-48, a bacterium isolated from electroplating effluent, was analysed. It was found that 198 mg\\/g (dry weight) of uranium was taken up from a 150 ppm (mg\\/l) solution of uranium when cells were maintained under

F. Malekzadeh; A. M. Latifi; M. Shahamat; M. Levin; R. R. Colwell

2002-01-01

92

DECONTAMINATION OF URANIUM  

DOEpatents

A process is given for separating fission products from uranium by extracting the former into molten aluminum. Phase isolation can be accomplished by selectively hydriding the uranium at between 200 and 300 deg C and separating the hydride powder from coarse particles of fissionproduct-containing aluminum. (AEC)

Spedding, F.H.; Butler, T.A.

1962-05-15

93

Hafnium-Zirconium Separation by Selective Reduction.  

National Technical Information Service (NTIS)

The report discusses an investigation directed toward selective reduction methods to recover most of the hafnium from zircon as hafnium-enriched zirconium-tetrachloride. Successive contacts of batches of mixed tetrachlorides were made with a reductant reg...

J. E. Mauser

1968-01-01

94

Separation of Molybdenum-Uranium by a Process Combining Ion Exchange Resin and Membranes  

NASA Astrophysics Data System (ADS)

The purpose of this study is to determine whether the electrodeionization with ion-exchange resin is suitable for removing uranium from a solution containing molybdenum. A hybrid process combining ion exchange (resins and membranes) using electric current. For this electroextraction process, the cation exchange resin is introduced into an electrodialysis cell and compressed between two cations exchange membranes. We have investigated a continuous electroextraction process. As important result we note that: The factor of selectivity,r, for molybdenum versus uranium is superior to 3; the concentration in radio active element (U3O8) is lower than 1.5 mg L-1 and small cell voltage is observed.

Lounis, A.; Setti, L.; Djennane, A.; Melikchi, R.

95

Separation of Uranium from Aqueous Solutions Using Al? and Fe?modified Titanium? and Zirconium Phosphates  

Microsoft Academic Search

The ability of four amorphous Al? and Fe?doped titanium and zirconium sorbents to separate U(VI) from acidic aqueous solutions (pHinit=3, ionic strength 0.1 M established by NaNO3) was investigated using a batch technique and instrumental neutron activation analysis. All investigated sorbents were found to be chemically stable and remove considerable amounts of uranium from acidic aqueous solutions (pHinit=3). The scanning electron

P. Misaelides; G. Gallios; S. Sarri; D. Zamboulis; E. Pavlidou; N. Kantiranis; I. Anousis; I. Zhuravlev; V. V. Strelko

2006-01-01

96

Isotope separation by selective photodissociation of glyoxal  

DOEpatents

Dissociation products, mainly formaldehyde and carbon monoxide, enriched in a desired isotope of carbon, oxygen, or hydrogen are obtained by the selective photodissociation of glyoxal wherein glyoxal is subjected to electromagnetic radiation of a predetermined wavelength such that photon absorption excites and induces dissociation of only those molecules of glyoxal containing the desired isotope.

Marling, John B. (Pleasanton, CA)

1976-01-01

97

THE RECOVERY OF URANIUM FROM GAS MIXTURE  

DOEpatents

A method of separating uranium from a mixture of uranium hexafluoride and other gases is described that comprises bringing the mixture into contact with anhydrous calcium sulfate to preferentially absorb the uranium hexafluoride on the sulfate. The calcium sulfate is then leached with a selective solvent for the adsorbed uranium. (AEC)

Jury, S.H.

1964-03-17

98

??????????????????????????????????????????????????????????????????????? D2EHPA SEPARATION OF URANIUM FROM TRISODIUM PHOSPHATE SOLUTION BY D2EHPA IMPREGNATED RESINS ????????? ???????????1, ??????? ??????????1 ??? ????? ????????????1  

Microsoft Academic Search

In the monazite ore breakdown by alkali process to separate nuclear elements and rare earth elements composed in this phosphate ore, trisodium phosphate byproduct from the digestion process may contain uranium up to 300 ppm. Therefore, it is necessary to purify this trisodium phosphate. This study has used di(2-ethylhexyl) phosphoric acid (D2EHPA) impregnated resins to extract uranium from the trisodium

Uthaiwan Injarean; Pipat Pichestapong; Wannee Srinuttrakul

99

Analysis of civilian processing programs in reduction of excess separated plutonium and high-enriched uranium  

SciTech Connect

The purpose of this preliminary investigation is to explore alternatives and strategies aimed at the gradual reduction of the excess inventories of separated plutonium and high-enriched uranium (HEU) in the civilian nuclear power industry. The study attempts to establish a technical and economic basis to assist in the formation of alternative approaches consistent with nonproliferation and safeguards concerns. The analysis addresses several options in reducing the excess separated plutonium and HEU, and the consequences on nonproliferation and safeguards policy assessments resulting from the interacting synergistic effects between fuel cycle processes and isotopic signatures of nuclear materials.

Persiani, P.J.

1995-12-31

100

Nonproliferation analysis of the reduction of excess separated plutonium and high-enriched uranium  

SciTech Connect

The purpose of this preliminary investigation is to explore alternatives and strategies aimed at the gradual reduction of the excess inventories of separated plutonium and high-enriched uranium (HEU) in the civilian nuclear power industry. The study attempts to establish a technical and economic basis to assist in the formation of alternative approaches consistent with nonproliferation and safeguards concerns. The analysis addresses several options in reducing the excess separated plutonium and HEU, and the consequences on nonproliferation and safeguards policy assessments resulting from the interacting synergistic effects between fuel cycle processes and isotopic signatures of nuclear materials.

Persiani, P.J.

1995-08-01

101

Separation and mass spectrometry of nanogram quantities of uranium and thorium from thorium-uranium dioxide fuels  

SciTech Connect

A microchemical procedure was developed for the separation and isotopic analysis of U and Th from irradiated (Th,U)O/sub 2/ fuel. The separation procedure consisted of two stages; in the first a tributyl phosphate impregnated resin bead was equilibrated with the dissolved fuel in 0.08 M HF/6 M HNO/sub 3/ solution. The bead sorbed approximately 1.7 ..mu..g of U and 4.8..mu..g of Th and provided good separation of these from the fission products. In the second stage, the U and Th were back-extracted into 0.025 M HF/8 M HNO/sub 3/ solution, which contained a small anion-exchange membrane disk. The disk adsorbed approximately 14 ng of U and 45 ng of Th, and subsequently was transferred to the ionizing filament of a thermal-ionization mass spectrometer and covered with a starch deposit. Sensitivities were sufficiently high for sequential analysis of these quantities of Th and U from a single disk. Isotopic data obtained for a combined U and Th standard showed excellent agreement with certified values: overall bias and precision were < 0.03% and 0.2% relative standard deviation, respectively, for both elements. The applicability of the procedure to uranium fuels was also demonstrated. 6 figures, 2 tables.

Green, L.W.; Elliot, N.L.; Longhurst, T.H.

1983-12-01

102

Validation of Electrochemically Modulated Separations Performed On-Line with MC-ICP-MS for Uranium and Plutonium Isotopic Analyses  

SciTech Connect

The most time consuming process in uranium or plutonium isotopic analyses is performing the requisite chromatographic separation of the actinides. Filament preparation for thermal ionization (TIMS) adds further delays, but is generally accepted due to the unmatched performance in trace isotopic analyses. Advances in Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) are beginning to rival the performance of TIMS. Methods, such as Electrochemically Modulated Separations (EMS) can efficiently pre-concentrate U or Pu quite selectively from small solution volumes in a matrix of 0.5 M nitric acid. When performed in-line with ICP-MS, the rapid analyte release from the electrode is fast, and large transient analyte signal enhancements of >100 fold can be achieved as compared to more conventional continuous nebulization of the original starting solution. This makes the approach ideal for very low level isotope ratio measurements. In this paper, some aspects of EMS performance are described. These include low level Pu isotope ratio behavior versus concentration by MC-ICP-MS and uranium rejection characteristics that are also important for reliable low level Pu isotope ratio determinations.

Liezers, Martin; Olsen, Khris B.; Mitroshkov, Alexandre V.; Duckworth, Douglas C.

2010-08-11

103

Testing a Technical-Scale Counterflow Compact Heat Exchanger for the Separation of Uranium Hexafluoride from Hydrogen.  

National Technical Information Service (NTIS)

When enriching the light uranium isotope U-235 according to the separation nozzle method, UF sub 6 and light auxiliary gas (H sub 2 ) must be separated from each other at the head as well as at the shoulder of the cascade. After pre-separation at a specia...

P. Hornberger D. Seidel H. Steinhaus

1981-01-01

104

Separation of Uranium Isotopes in the Separating Nozzle at Backdraft of the Heavy Fraction.  

National Technical Information Service (NTIS)

H sub 2 /UF sub 6 mixtures were studied under laboratory conditions to determine how the backdraft of the heavy fraction, depleted with respect to exp 235 U, is influencing the efficiency of the separation nozzle, what effects tolerance variations of geom...

U. Heiden

1978-01-01

105

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

106

Selection of membrane separation processes for treatment of tannery effluent  

Microsoft Academic Search

Effluents from four units of a tannery, namely, soaking, liming, deliming-bating and dyeing were tested using molecular weight cut-off membranes in separation processes using a stirred cell in continuous mode. A suitable membrane was selected and the effluent was treated with the selected membrane, in a continuous cross flow cell. Various properties, namely, chemical oxygen demand (COD), biological oxygen demand

Chandan Das; Sunando DasGupta; Sirshendu De

107

Selective separation of aspirin using molecularly imprinted polymers  

Microsoft Academic Search

The molecular imprinting technique (MIT) is a potential method for creating molecular recognition sites with high selectivity to the target molecule in polymeric materials. The goal of this study was the selective separation of aspirin (AS) having various effects as pharmaceutics using the molecularly imprinted polymers (MIPs). The MIPs were prepared with styrene, 4-vinylpyridine (4-VPy) as a functional monomer, templates

Hun-Soo Byun; Young-Nam Youn; Yeon-Hum Yun; Soon-Do Yoon

2010-01-01

108

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

109

Dissolution of uranium and vanadium from aerodynamically size-separated ore particles in a simulated lung fluid  

Microsoft Academic Search

The purpose of the project was to gain some insight into the long-term clearance of particulate lung burdens. Quantitative relations were sought between the physical-chemical properties of uranium ore particles and their reported clearance from the lung. The dissolution rate constant for tyuyamunite ore particles was measured for sieved and aerodynamically separated fractions. The ore was separated aerodynamically by using

1976-01-01

110

Determination of uranium and thorium in complex samples using chromatographic separation, ICP-MS and spectrophotometric detection.  

PubMed

The paper describes a research of possible application of UTEVA and TRU resins and anion exchanger AMBERLITE CG-400 in nitrate form for the isolation of uranium and thorium from natural samples. The results of determination of distribution coefficient have shown that uranium and thorium bind on TRU and UTEVA resins from the solutions of nitric and hydrochloric acids, and binding strength increases proportionally to increase the concentration of acids. Uranium and thorium bind rather strongly to TRU resin from the nitric acid in concentration ranging from 0.5 to 5 mol L(-1), while large quantities of other ions present in the sample do not influence on the binding strength. Due to the difference in binding strength in HCl and HNO(3) respectively, uranium and thorium can be easily separated from each other on the columns filled with TRU resin. Furthermore, thorium binds to anion exchanger in nitrate form from alcohol solutions of nitric acid very strongly, while uranium does not, so they can be easily separated. Based on these results, we have created the procedures of preconcentration and separation of uranium and thorium from the soil, drinking water and seawater samples by using TRU and UTEVA resins and strong base anion exchangers in nitrate form. In one of the procedures, uranium and thorium bind directly from the samples of drinking water and seawater on the column filled with TRU resin from 0.5 mol L(-1) HNO(3) in a water sample. After binding, thorium is separated from uranium with 0.5 mol L(-1) HCl, and uranium is eluted with deionised water. By applying the described procedure, it is possible to achieve the concentration factor of over 1000 for the column filled with 1g of resin and splashed with 2L of the sample. Spectrophotometric determination with Arsenazo III, with this concentration factor results in detection limits below 1 microg L(-1) for uranium and thorium. In the second procedure, uranium and thorium are isolated from the soil samples with TRU resin, while they are separated from each other on the column filled with anion exchanger in alcohol solutions. Anion exchanger combined with alcohol solutions enables isolation of thorium from soil samples and its separation from a wide range of elements, as well as spectrophotometric determination, ICP-MS determination, and other determination techniques. PMID:19782236

Rozmari?, Martina; Ivsi?, Astrid Gojmerac; Grahek, Zeljko

2009-07-08

111

Uranium  

Microsoft Academic Search

\\u000a Uranium compounds have been used as colorants since Roman times (Caley, 1948). Uranium was discovered as a chemical element\\u000a 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

Ingmar Grenthe; Janusz Drozdzynski; Takeo Fujino; Edgar C. Buck; Thomas E. Albrecht-Schmitt; Stephen F. Wolf

2011-01-01

112

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. 4 figs.

Horton, J.A.; Hayden, H.W. Jr.

1995-05-30

113

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

114

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

SciTech Connect

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 within the defined scope of the project, as are aerial surveying procedures, uranium reserves and resources, and universally applied uranium research. References used by DOE-NURE contractors in completing their aerial reconnaissance survey reports have been included at the request of the Grand Junction Office, DOE. The following indexes are provided to aid the user in locating reference of interest: author, keyword, geographic location, quadrangle name, geoformational index, and taxonomic name.

White, M.B.; Garland, P.A. (comps.)

1977-10-01

115

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

116

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

2006-11-18

117

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

118

Separation and measurement of thorium, plutonium, americium, uranium and strontium in environmental matrices.  

PubMed

A technique for the isolation of thorium (Th), plutonium (Pu), americium (Am), uranium (U) and strontium (Sr) isotopes from various environmental matrices has been adapted from a previously published method specific to water samples (Maxwell, 2006). Separation and isolation of the various elemental fractions from a single sub-sample is possible, thereby eliminating the need for multiple analyses. The technique involves sample dissolution, concentration via calcium phosphate co-precipitation, rapid column extraction using TEVA™, TRU™ and Sr-Spec™ resin cartridges, alpha spectrometry for Th, Pu, U and Am and Cerenkov counting for Sr. Various standard reference materials were analysed and chemical yields are in the range of 70-80% for Th, Am, U and Sr and 50-60% for Pu. Sample sizes of up to 10 L for water, 5 g for dry soil and sediment and 10 g for dry vegetation and seaweed can be processed using this technique. PMID:20609501

Harrison, Jennifer J; Zawadzki, Atun; Chisari, Robert; Wong, Henri K Y

2010-07-07

119

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

120

Method of separating isotopes of uranium employing UO2(Hfacac)2. l with an improved photon efficiency  

SciTech Connect

Methods for separating uranium isotopes are disclosed including irradiating certain uranyl ion-containing compounds with radiation of a wavelength, lambda, at which the compounds have a predetermined absorption cross section sigma lambda at a power> kw/cm2 times sigma lambda /4 X 10-18 cm2.

Hall, R.B.

1982-04-13

121

Anion Separation by Selective Crystallization of Metal-Organic-Frameworks  

Microsoft Academic Search

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-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

Radu Custelcean; Radu; Bruce A. Moyer

2006-01-01

122

Possibility of isotope separation by selective radiative scattering  

SciTech Connect

It is demonstrated by means of a specific calculation that a velocity-changing radiative collision can lead to efficient isotope separation. Compared with photodissociative or photoionization techniques, selective scattering affords the advantage of a greater degree of control over the initial conditions, hence greater scope for optimization. This advantage is particularly important at the collision temperatures (approx.1 K), where radiative inelastic collisions are most efficient.

Hutchinson, M.; George, T.F.; DeVries, P.L.

1983-07-01

123

(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

124

Removal of uranium from aqueous HF solutions  

SciTech Connect

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 separating the solution from the settled particulates. The CaF2 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, H.; Seltzer, S.F.

1980-11-18

125

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

126

The synthesis, characterization and application of iron oxide nanocrystals in magnetic separations for arsenic and uranium removal  

NASA Astrophysics Data System (ADS)

Arsenic and uranium in the environment are hazardous to human health and require better methods for detection and remediation. Nanocrystalline iron oxides offer a number of advantages as sorbents for water purification and environmental remediation. First, highly uniform and crystalline iron oxide nanocrystals (nMAG) were prepared using thermal decomposition of iron salts in organic solutions; for the applications of interest in this thesis, a central challenge was the adaptation of these conventional synthetic methods to the needs of low infrastructure and economically disadvantaged settings. We show here that it is possible to form highly uniform and magnetically responsive nanomaterials using starting reagents and equipment that are readily available and economical. The products of this approach, termed the 'Kitchen Synthesis', are of comparable quality and effectiveness to laboratory materials. The narrow size distributions of the iron oxides produced in the laboratory synthesis made it possible to study the size-dependence of the magnetic separation efficiency of nanocrystals; generally as the diameter of particles increased they could be removed under lower applied magnetic fields. In this work we take advantage of this size-dependence to use magnetic separation as a tool to separate broadly distributed populations of magnetic materials. Such work makes it possible to use these materials in multiplexed separation and sensing schemes. With the synthesis and magnetic separation studies of these materials completed, it was possible to optimize their applications in water purification and environmental remediation. These materials removed both uranium and arsenic from contaminated samples, and had remarkably high sorption capacities --- up to 12 wt% for arsenic and 30 wt% for uranium. The contaminated nMAG is removed from the drinking water by either retention in a sand column, filter, or by magnetic separation. The uranium adsorption process was also utilized for the enhanced detection of uranium in environmental matrices. By relying on alpha-particle detection in well-formed and dense nMAG films, it was possible to improve soil detection of uranium by more than ten-thousand-fold. Central for this work was a detailed understanding of the chemistry at the iron oxide interface, and the role of the organic coatings in mediating the sorption process.

Mayo, John Thomas

127

BASIC STUDIES OF THE SEPARATION OF URANIUM HEXAFLUORIDE FROM MIXTURES CONTAINING CHLORINE TRIFLUORIDE AND HYDROGEN FLUORIDE  

Microsoft Academic Search

Processes for the conversion of uranium compounds or uranium metal to ;\\u000a uranium hexafluoride ordinarily involve the use of a powerful fluorinating agent. ;\\u000a Elemental fluorine is used when the scale of operations justifies the ;\\u000a construction of a fluorine generating plant, but for smaller operation the use of ;\\u000a the interhalogens of fluorine has definite advantages. These compounds provide

H. A. Bernhardt; E. J. Barber; W. Jr. Davis; R. M. McGill

1958-01-01

128

Separation of uranium from carbonate-containing solutions thereof by direct precipitation  

SciTech Connect

A direct precipitation method based on the insolubility of uranyl phosphate in carbonate containing solutions at pH 6-6.5 and its insolubility at pH 8 is described. The method eliminates the use of ion exchange columns for removing uranium values from uranium leachates and can be readily applied to an integrated field operation.

Otto, J.B. Jr.

1983-10-18

129

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

130

Amberlite XAD-4 functionalized with succinic acid for the solid phase extractive preconcentration and separation of uranium(VI).  

PubMed

Amberlite XAD-4 resin has been functionalized with succinic acid by coupling it with dibromosuccinic acid after acetylation. The resulting resin has been characterized by FT-IR, elemental analysis and TGA and has been used for preconcentrative separation of uranium(VI) from host of other inorganic species prior to its determination by spectrophotometry. The optimum pH value for quantitative sorption of uranium(VI) in both batch and column modes is 4.5-8.0 and desorption can be achieved by using 5.0ml of 1.0moll(-1) HCl. The sorption capacity of functionalized resin is 12.3mgg(-1). Calibration graphs were rectilinear over the uranium(VI) concentrations in the range 5-200mugl(-1). Five replicate determinations of 50mug of uranium(VI) present in 1000ml of solution gave a mean absorbance of 0.10 with a relative standard deviation of 2.56%. The detection limit corresponding to three times the standard deviation of the blank was found to be 2mugl(-1). Various cationic and anionic species at 200-fold amounts do not interfere during the preconcentration of 5.0mug of uranium(VI) present in 1000ml (batch) or 100ml (column) of sample solution. Further, adsorption kinetic and isotherm studies were also carried out by a batch method to understand the nature of sorption of uranium(VI) with the succinic acid functionalized resin. The accuracy of the developed solid phase extractive preconcentration method in conjunction with Arsenazo III procedure was tested by analyzing marine sediment (MESS-3) and soil (IAEA soil-7) reference material. Further, the above procedure has been successfully employed for the analysis of soil and sediment samples. PMID:18969783

Metilda, P; Sanghamitra, K; Mary Gladis, J; Naidu, G R K; Prasada Rao, T

2005-01-15

131

Uranium  

Microsoft Academic Search

By 1911, the atomic weight of uranium had been refined to 238.5 (Gmelin, vol. A2, 1980a). The natural isotope 235U was discovered in 1935 by mass spectrometry. The artificial isotope 239U, which is the precursor of 239Np and 239Pu, was postulated and identified by Hahn and coworkers (Hahn et al., 1937; Meitner et al., 1937) as a 23 min half-life

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

2006-01-01

132

Actinides and decay products in selected produce and bioindicators in the vicinity of a uranium plant.  

PubMed

Cypress needles collected at the edge of the Malvési uranium facility (SW France) exhibit enhanced activities of actinides and some decay products (uranium, americium, plutonium, (230)Th, (226)Ra) compared to a remote site. These enhanced activities resulted from the release of U via smokestacks and passive release from former artificial ponds located inside the nuclear site. Enhanced activities are also observed in selected produce (wheat, lettuce, fruits) sampled from the edge of the site. However, excess actinides measured in wheat grains in 2007 are inconsistent with the activities and the uranium ratio measured in the soils. This result suggests that the studied annual crops were contaminated mainly through the short-term release of airborne actinides, and that other transfer pathways, such as, uptake through the roots or adhesion of soil particles, were negligible. PMID:21487575

Pourcelot, L; Boulet, B; Le Corre, C; de Vismes Ott, A; Cagnat, X; Loyen, J; Fayolle, C; Van Hecke, W; Martinez, B; Petit, J; Kaltenmeier, R; Gieré, R

2011-04-12

133

Selective Isotope Determination of Uranium using HR-RIMS  

SciTech Connect

The detection of lowest abundances of the ultra trace isotope {sup 236}U in environmental samples requires an efficient detection method which allows a high elemental and isotopic selectivity to suppress neighbouring isotopes of the same element and other background. High Resolution Laser Resonance Ionization Mass Spectrometry (HR-RIMS) uses the individual electron structure of each isotope to provide an outstanding element and isotope selective ionization.

Raeder, S.; Fies, S.; Wendt, K. D. A. [Institut fuer Physik, Johannes Gutenberg Universitaet Mainz, 55128 Mainz (Germany); Tomita, H. [Nagoya University (Japan)

2009-03-17

134

Device for selectively separating and connecting a rotatable shaft  

SciTech Connect

Device for selectively separating and connecting a rotatable shaft, such as the crankshaft of an internal combustion engine, to a flywheel assembly of a friction clutch has a bearing in which the flywheel assembly is rotatable relative to the shaft, a friction plate non-rotatably connected to the shaft and having friction surfaces disposed at the opposite sides thereof, two pressure plates forming part of the flywheel assembly and each having a friction surface cooperating with one of the friction surfaces of the friction plates, the pressure plate being axially movably but non-rotatably connected to each other and, one of the pressure plates being held against axial movement relative to the bearing, operating means for moving the other of the pressure plates axially, spring means disposed on the friction plate between the connection to the shaft and the friction surfaces disposed thereon for biasing the friction plate in direction away from the axially-fixed pressure plate, and stop means for limiting the extent of axial movement of the friction surfaces of the friction plate.

Maucher, P.; Friedmann, O.

1985-06-04

135

Enriched Uranium  

NSDL National Science Digital Library

This Wikipedia website provides information about the various concentrations of uranium used for different applications. Topics include a brief description of the grades of uranium and methods of isotope separation. There are also links to other aspects of uranium enrichment and related information. This information lays the foundation for informed discussion about the potential of nuclear energy and the risks of nuclear proliferation.

Wikipedia

136

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

137

Source separation, selective collection and in reactor digestion of biowaste.  

PubMed

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 participants in the alternating collection program (one week biowaste and the next week non recyclable fraction) are pleased with separate collection of biowaste. Dominating problems that arise in case of alternating collection are a repulsive odor and an infestation with flies and maggots. By expanding the definition of biowaste to include non recyclable or soiled paper like dirty newspapers, table napkins and paper handkerchiefs, most of these problems can be overcome without changing the way compostable waste is collected and processed. The expanded definition of biowaste was used in this paper. Over a 12 month period a quality survey of the collected biowaste was conducted by the composting facility Intercompost, Hoeselt, Belgium. A special aspect was the fact that in one participating community baby diapers were included in the soiled paper fraction; this is called "biowaste+". The biowaste+ had a 10% non recyclable paper fraction opposed to only 1-2% of non recyclable paper present in the conventional biowaste. Baby diapers were a rather notable part (more than 80%) of this non recyclable paper fraction of biowaste+ and as a consequence might contribute to a large extent to improve the collection and treatment of biowaste. It was demonstrated that rural districts yielded about 35% more biowaste than more urban districts; resp. +/- 122 kg biowaste/capita. year versus +/- 90 kg biowaste/capita. year. In Hoeselt the biowaste+ yield was about 130 kg/capita.year. Biowaste+ is also separately collected in another Belgium community, namely Brecht. The purity level of the biowaste+ and the amount of non recyclable paper (including diapers) were comparable with the results of Hoeselt. In Hoeselt the biowaste+ fraction is composted aerobically. In Brecht on the other hand, the biowaste+ is processed using the Dry Anaerobic Composting process (DRANCO). The latter process is discussed in more detail. The biological start-up of the dry anaerobic composting installation at Brecht, Belgium, is reported. The reactor has a total volume of 808 m3 and a design capacity of 730 m3. After 2 months of start up, the fermentor was at full loading rate, i.e. 8 kg bVS/m3 reactor.day and the installation was working at full capacity, i.e. 40 ton/day.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7741530

Gellens, V; Boelens, J; Verstraete, W

1995-01-01

138

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

139

Separating the Minor Actinides Through Advances in Selective Coordination Chemistry  

SciTech Connect

This report describes work conducted at the Pacific Northwest National Laboratory (PNNL) in Fiscal Year (FY) 2012 under the auspices of the Sigma Team for Minor Actinide Separation, funded by the U.S. Department of Energy Office of Nuclear Energy. Researchers at PNNL and Argonne National Laboratory (ANL) are investigating a simplified solvent extraction system for providing a single-step process to separate the minor actinide elements from acidic high-level liquid waste (HLW), including separating the minor actinides from the lanthanide fission products.

Lumetta, Gregg J.; Braley, Jenifer C.; Sinkov, Sergey I.; Carter, Jennifer C.

2012-08-22

140

Method of removing niobium from uranium-niobium alloy  

SciTech Connect

This patent describes a method of removing niobium from a uranium-niobium alloy. It comprises dissolving the uranium-niobium alloy metal pieces in a first aqueous solution containing an acid selected from the group consisting of hydrochloric acid and sulfuric acid and fluoboric acid as a catalyst to provide a second aqueous solution, which includes uranium (U{sup +4}), acid radical ions, the acids insolubles including uranium oxides and niobium oxides; adding nitric acid to the insolubles to oxidize the niobium oxides to yield niobic acid and to complete the solubilization of any residual uranium; and separating the niobic acid from the nitric acid and solubilized uranium.

Pollock, E.N.; Schlier, D.S.; Shinopulos, G.

1992-01-28

141

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

142

Highly selective separations by capillary electrochromatography: molecular imprint polymer sorbents  

Microsoft Academic Search

Molecular imprint polymers (MIPs) are synthesized in the presence of a template, or ‘imprint’ molecule which results in the formation of specific recognition cavities complementary to the template in shape and chemical functionality. The resultant MIP then acts as a selective binding medium for the template molecule. The utility of MIPs lies in the selectivity of the rebinding process, which

Patrick T Vallano; Vincent T Remcho

2000-01-01

143

Separability-based multiscale basis selection and feature extraction for signal and image classification  

Microsoft Academic Search

Algorithms for multiscale basis selection and feature extraction for pattern classification problems are presented. The basis selection algorithm is based on class separability measures rather than energy or entropy. At each level the “accumulated” tree-structured class separabilities obtained from the tree which includes a parent node and the one which includes its children are compared. The decomposition of the node

Kamran Etemad; Rama Chellappa

1998-01-01

144

Review of Selective Ion Separations at BYU Using Liquid Membrane and Solid Phase Extraction Procedures  

Microsoft Academic Search

Research in selective ion separations at Brigham Young University hasinvolved the use of liquid membranes of the bulk, emulsion, thin sheetsupported, hollow fiber supported, and two-module hollow fiber supportedtypes as well as solid phase extraction using immobilized ligands. By use ofdesigned cation and anion selective macrocyclic ligands, it has beenpossible to accomplish a wide range of interesting separations. Theprinciples underlying

Reed M. Izatt

1997-01-01

145

Feasible separations and entrainer selection rules for heteroazeotropic batch distillation  

Microsoft Academic Search

A feasibility analysis is presented for the separation of close-boiling and azeotropic (minimum- and maximum-boiling) binary mixtures into pure components by the addition of an entrainer introducing a heterogeneous azeotrope. The analysis is done for both the conventional batch rectifier and the multivessel batch column. The analysis is theoretical and based on the assumptions of total reflux\\/reboil ratios and infinite

S. Skouras; V. Kiva; S. Skogestad

2005-01-01

146

Facilitated separation of a select gas through an ion exchange membrane  

Microsoft Academic Search

Suitable for separating COâ, HâS, olefins, etc., from a gas mixture, GE's selective purification process uses an ion-exchange membrane that has specific mobile counter-ions electrostatically retained in it. These counter-ions react reversibly with the specific gas molecules to be separated. Besides being highly selective, the membrane facilitates gas transport across it, thus accomplishing a separation superior to that of other

S. G. Kimura; W. J. Ward; S. L. Matson

1982-01-01

147

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

148

Isotope separation by selective charge conversion and field deflection  

DOEpatents

A deuterium-tritium separation system wherein a source beam comprised of positively ionized deuterium (D.sup.+) and tritium (T.sup.+) is converted at different charge-exchange cell sections of the system to negatively ionized deuterium (D.sup.-) and tritium (T.sup.-). First, energy is added to the beam to accelerate the D.sup.+ ions to the velocity that is optimum for conversion of the D.sup.+ ions to D.sup.- ions in a charge-exchange cell. The T.sup.+ ions are accelerated at the same time, but not to the optimum velocity since they are heavier than the D.sup.+ ions. The T.sup.+ ions are, therefore, not converted to T.sup.- ions when the D.sup.+ ions are converted to D.sup.- ions. This enables effective separation of the beam by deflection of the isotopes with an electrostatic field, the D.sup.- ions being deflected in one direction and the T.sup.+ ions being deflected in the opposite direction. Next, more energy is added to the deflected beam of T.sup.+ ions to bring the T.sup.+ ions to the optimum velocity for their conversion to T.sup.- ions. In a particular use of the invention, the beams of D.sup.- and T.sup.- ions are separately further accelerated and then converted to energetic neutral particles for injection as fuel into a thermonuclear reactor. The reactor exhaust of D.sup.+ and T.sup.+ and the D.sup.+ and T.sup.+ that was not converted in the respective sections is combined with the source beam and recycled through the system to increase the efficiency of the system.

Hickman, Robert G. (Livermore, CA)

1978-01-01

149

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

150

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

151

Selected methods of reflux-hydrocarbon gas separation process  

Microsoft Academic Search

A process is described for the recovery of components of volatile gas containing methane and heavier components wherein one of three specific methods of reflux is used the selection being dependent upon the specific requirements of rectification, in each instance the process consisting of introducing a primary stream of feed gas under pressure into a heat exchange unit to lower

Cook

1986-01-01

152

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

153

PROCESS FOR SEPARATING PLUTONIUM FROM IMPURITIES  

DOEpatents

A method is described for separating plutonium from aqueous solutions containing uranium. It has been found that if the plutonium is reduced to its 3+ valence state, and the uranium present is left in its higher valence state, then the differences in solubility between certain salts (e.g., oxalates) of the trivalent plutonium and the hexavalent uranium can be used to separate the metals. This selective reduction of plutonium is accomplished by adding iodide ion to the solution, since iodide possesses an oxidation potential sufficient to reduce plutonium but not sufficient to reduce uranium.

Wahl, A.C.

1957-11-12

154

Selective separation of Ga 3+ through membrane impregnated with N-octadecanoyl- N-phenylhydroxylamine  

Microsoft Academic Search

Selective separation of Ga3+ was studied through a microporous polypropylene membrane impregnated with N-octadecanoyl-N-phenylhydroxylamine (ODPHA). The present membrane selectively concentrated Ga3+ from a Ga3+Al3+ mixture against the concentration gradient, with a counter flow of H+ as a driving force. The selective separation of Ga3+ was found to be attributed to the specific interaction between ODPHA and Ga3+. A microporous membrane

Hiroshi Okushita; Takeo Shimidzu

1995-01-01

155

Investigation of extractive separation of uranium and vanadium from sulphuric acid leaching liquors of uranium ore (2). Reduction of Fe(III) from sulphuric acid.  

National Technical Information Service (NTIS)

Reduction condition of Fe(III) to extract uranium and vanadium with HDEHP from sulphuric acid leaching liquors of uranium ore was examined. It was shown that in the system of oxidation-reduction consisted of many ionic pairs can reduce Fe(III) with iron s...

Han Hi Jong

1989-01-01

156

Radioactive Decay Properties of CANDU Fuel. Volume 1: The Natural Uranium Fuel Cycle. Part 1: Starting Materials: Uranium Ore, Separated Uranium and Uranium Mill Tailings, and Part 2: Irradiated Fuel.  

National Technical Information Service (NTIS)

The computer code CANIGEN was used to obtain the mass, activity, decay heat and toxicity of CANDU fuel and its component isotopes. Data are also presented on gamma spectra and neutron emissions. Part 1 presents these data for unirradiated fuel, uranium or...

L. J. Clegg J. R. Coady

1977-01-01

157

Iron EDTA chelate catalyzed oxidation of uranium  

SciTech Connect

Uranium ore deposits which contain uranium in the relatively insoluble tetravalent state are readily selectively leached in situ to recover relatively pure uranium compounds, by: (A) passing through the ore deposit a relatively dilute aqueous leach solution of ammonium bicarbonate, ferric ammonium ethylenediaminetetraacetic acid (EDTA), and a source of oxygen, the leach solution converting the tetravalent uranium to hexavalent uranium which readily dissolves in the leach solution; (B) withdrawing the reacted leach solution enriched in dissolved uranium from the ore deposit; and (C) stripping the uranium from the withdrawn leach solution. The stripping of the uranium from the leach solution is preferably accomplished by countercurrent flow of the enriched leach solution to a column of base anion exchange material which preferentially extracts the uranium. Base anion exchange material loaded with uranium is separated from the leach solution and is treated with an aqueous alkaline eluant to extract the uranium and to regenerate the base anion exchange material. The stripped leach solution is adjusted by adding ammonium bicarbonate, peroxide, and ferric ammonium edta, and its ph corrected if necessary, and the leach solution is recycled through the ore deposit. The uranium bearing eluant is then acidified and treated with ammonia to precipitate relatively pure ammonium diuranate (Adu).

Jackovitz, J.F.; Panson, A.J.; Pantier, E.A.

1981-01-06

158

Natural Gamma Emitters after a Selective Chemical Separation of a TENORM residue: Preliminary Results  

NASA Astrophysics Data System (ADS)

An analytical procedure was established in order to obtain selective fractions containing radium isotopes (228Ra), thorium (232Th), and rare earths from RETOTER (REsíduo de TÓrio e TErras Raras), a solid residue rich in rare earth elements, thorium isotopes and small amount of natural uranium generated from the operation of a thorium pilot plant for purification and production of pure thorium nitrate at IPEN -CNEN/SP. The paper presents preliminary results of 228Ra, 226Ra, 238U, 210Pb, and 40K concentrations in the selective fractions and total residue determined by high-resolution gamma spectroscopy, considering radioactive equilibrium of the samples.

de Freitas, Antonio Alves; Dos Santos, Adir Janete Godoy; Pecequilo, Brigitte Roxana Soreanu; Abra~O, Alcídio

2008-08-01

159

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

2006-12-11

160

Monochromatic wavelength dispersive x-ray fluorescence providing sensitive and selective detection of uranium  

SciTech Connect

Monochromatic wavelength dispersive X-ray fluorescence (MWDXRF) is a sensitive and selective method for elemental compositional analyses. The basis for this instrumental advance is the doubly curved crystal (DCC) optic. Previous work has demonstrated the feasibility of sensitive trace element detection for yttrium as a surrogate for curium in aqueous solutions. Additional measurements have demonstrated similar sensitivity in several different matrix environments which attests to the selectivity of the DCC optic as well as the capabilities of the MWDXRF concept. The objective of this effort is to develop an improved Pu characterization method for nuclear fuel reprocessing plants. The MWDXRF prototype instrument is the second step in a multi-year effort to achieve an improved Pu assay. This work will describe a prototype MWDXRF instrument designed for uranium detection and characterization. The prototype consists of an X-ray tube with a rhodium anode and a DCC excitation optic incorporated into the source. The DCC optic passes the RhK{alpha} line at 20.214 keV for monochromatic excitation of the sample. The source is capable of 50 W power at 50 kV and 1.0 mA operation. The x-ray emission from the sample is collected by a DCC optic set at the UL{alpha} line of 13.613 keV. The collection optic transmits the UL{alpha} x-rays to the silicon drift detector. The x-ray source, sample, collection optic and detector are all mounted on motion controlled stages for the critical alignment of these components. The sensitivity and selectivity of the instrument is obtained through the monochromatic excitation and the monochromatic detection. The prototype instrument performance has a demonstrated for sensitivity for uranium detection of around 2 ppm at the current state of development. Further improvement in sensitivity is expected with more detailed alignment.

Havrilla, George J [Los Alamos National Laboratory; Collins, Michael L [Los Alamos National Laboratory; Montoya, Velma M [Los Alamos National Laboratory; Chen, Zewu [XOS; Wei, Fuzhong [XOS

2010-01-01

161

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.

Kokkinakis, Kostas; Loizou, Philipos C.

2010-01-01

162

Sulfate Separation by Selective Crystallization of a Urea-Functionalized Metal-Organic Framework  

SciTech Connect

Encapsulation of SO{sub 4}{sup 2-} into a Ni coordination framework functionalized with urea anion-binding groups allows selective separation of this strongly hydrophilic anion from a highly competitive aqueous environment.

Custelcean, Radu [ORNL; Sellin, Vincent [ORNL; Moyer, Bruce A [ORNL

2007-01-01

163

Development of a composite palladium membrane for selective hydrogen separation at high temperature  

Microsoft Academic Search

In this paper a method is described for development of a composite palladium membrane for selective hydrogen separation at high temperature. Electroless plating is used to form a thin palladium film on a silver porous substrate. The composite formed showed excellent mechanical strength and very large selectivity for hydrogen. The studies performed so far suggest that electroless plating can be

Rakesh Govind; Devendra Atnoor

1991-01-01

164

Method for converting uranium oxides to uranium metal  

SciTech Connect

A method for converting uranium oxide to uranium metal is described comprising the steps of heating uranium oxide in the presence of a reducing agent to a temperature sufficient to reduce the uranium oxide to uranium metal and form a heterogeneous mixture of a uranium metal product and oxide by-products, heating the mixture in a hydrogen atmosphere at a temperature sufficient to convert uranium metal in the mixture to uranium hydride, cooling the resulting uranium hydride-containing mixture to a temperature sufficient to produce a ferromagnetic transition in the uranium hydride, magnetically separating the cooled uranium hydride from the mixture, and thereafter heating the separated uranium hydride in an inert atmosphere to a temperature sufficient to convert the uranium hydride to uranium metal.

Duerksen, W.K.

1988-01-05

165

Selective dissolution and recovery of depleted uranium from armor plate. Final report, 26 June 1986-5 May 1987  

SciTech Connect

The impacted armor targets used in testing high density armor-piercing ammunition containing depleted uranium (DU) are subject to disposal as low-level radioactive waste. Because of the costs associated with disposal of the entire armor plate and the limited use of secured commercial sites in the future, the U.S. Army is seeking to identify and evaluate new technologies for decontaminating these armor plates. The objectives of this Phase I SBIR program are two-fold, namely: to develop a selective solvent that can decontaminate impacted armor targets containing DU for disposal or recycle, and to identify and characterize technologies that can remove depleted uranium from the solvent for solvent recycle and uranium recovery for easier hazardous-waste disposal.

Czupryna, G.; Levy, R.D.; Gold, H.

1987-05-05

166

Determination of uranium and thorium in complex samples using chromatographic separation, ICP-MS and spectrophotometric detection  

Microsoft Academic Search

The paper describes a research of possible application of UTEVA and TRU resins and anion exchanger AMBERLITE CG-400 in nitrate form for the isolation of uranium and thorium from natural samples. The results of determination of distribution coefficient have shown that uranium and thorium bind on TRU and UTEVA resins from the solutions of nitric and hydrochloric acids, and binding

Martina Rožmari?; Astrid Gojmerac Ivši?; Željko Grahek

2009-01-01

167

PROCESS FOR RECOVERING URANIUM  

DOEpatents

A process is described for recovering uranium from deposits on stainless steel liner surfaces of calutrons. The deposit is removed from the stainless steel surface by washing with aqueous nitric acid. The solution obtained containing uranium, chromium, nickels copper, and iron is treated with excess of ammonium hydroxide to precipitatc the uranium, irons and chromium and convert thc nickel and copper to soluble ammonia complexions. The precipitated material is removed, dried, and treated with carbon tetrachloride at an elevated temperature of about 500 to 600 deg C to form a vapor mixture of UCl/sub 4/, UCl/sub 5/, FeCl/ sub 3/, and CrCl/sub 4/. The UCl/sub 4/ is separated from this vapor mixture by selective fractional condensation at a temprrature of about 300 to400 deg C.

MacWood, G.E.; Wilder, C.D.; Altman, D.

1959-03-24

168

PROCESS FOR RECOVERYING URANIUM  

DOEpatents

A process useful in recovering uranium from deposits on stainless steel liner surfaces of calutrons is presented. The deposit is removed from the stainless steel surface by washing with aqueous nitric acid. The solution obtained containing uranium, chromium, nickel, copper, and iron is treated with an excess of ammonium hydroxide to precipitnte the uranium, iron, and chromium and convert the nickel and copper to soluble ammonio complexions. The precipitated material is removed, dried and treated with carbon tetrachloride at an elevated temperature of about 500 to 600 deg C to form a vapor mixture of UCl/ sub 4/, UCl/sub 5/, FeCl/sub 3/, and CrCl/sub 4/. The UCl/sub 4/ is separated from this vapor mixture by selective fractional condensation at a temperature of about 500 to 400 deg C.

MacWood, G.E.; Wilder, C.D.; Altman, D.

1959-03-24

169

Sequential separation of light rare-earth elements, thorium and uranium by miniaturized extraction chromatography: Application to isotopic analyses of silicate rocks  

Microsoft Academic Search

A new method for the concomitant separation of the light rare-earth elements (LREEs), thorium and uranium is described, and applied to the determination of 143Nd144Nd ratios, and concentrations of Sm, Nd, Th and U in silicate rocks, using isotope dilution and thermal ionization mass spectrometry. The proposed scheme is based on two recently introduced extraction chromatographic materials, referred to as

Christian Pin; JoséFrancisco Santos Zalduegui

1997-01-01

170

Improvement of multi jet low pressure impactor for high collection efficiency of UF5 in the molecular laser isotope separation of uranium  

Microsoft Academic Search

A numerical and experimental study for the collection of photo-produced UF5 particles was performed for the low pressure impactors which have different design factors at typical flow conditions (upstream pressure of the impactor = 10–15 Torr, pressure ratio of downstream to upstream of the impactor, PdownPup = 0.2–0.5) in the molecular laser isotope separation of uranium at RIKEN (RIMLIS). Smaller

Yoshikazu Kuga; Benjamin Jurcik; Sakae Satooka; Kazuo Takeuchi

1995-01-01

171

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

Microsoft Academic Search

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

Allan Hong; Ravindra K. Mariwala; Michael S. Kane; Henry C. Foley

1995-01-01

172

Insulator-based dielectrophoresis for the selective concentration and separation of live bacteria in water  

Microsoft Academic Search

Insulator-based dielectrophoresis (iDEP) was utilized to separate and concentrate selectively mixtures of two species of live bacteria simultaneously. Four species of bacteria were studied: the Gram-negative Escherichia coli and the Gram-positive Bacillus subtilis, B. cereus, and B. megaterium. Under an applied direct current (DC) electric field all the bacterial species exhibited negative dielectrophoretic behavior. The dielectrophoretic separations were carried out

Blanca H. Lapizco-Encinas; Blake A. Simmons; Eric B. Cummings; Yolanda Fintschenko

2004-01-01

173

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

174

Selective separation of copper by membrane-electro-winning and its application in etchant recycling  

Microsoft Academic Search

A close-looped process based on the membrane separation and electrolysis is proposed to regenerate the copper etchant in-situ,\\u000a recover copper on-site and reuse it. It is characterized by selective separation of copper from the spent etchant, which is\\u000a accomplished by the ion exchange membrane-electrowinning, and at the same time the other components useful for etching are\\u000a reclaimed. The experiments show

De-liang Li; Ren-hua Chen

2005-01-01

175

Method for converting uranium oxides to uranium metal  

SciTech Connect

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 mixtures is then cooled to a temperature less than -100/sup 0/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, W.K.

1987-01-01

176

Method for converting uranium oxides to uranium metal  

SciTech Connect

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

177

DECONTAMINATION OF URANIUM  

DOEpatents

This patent deals with the separation of rare earth and other fission products from neutron bombarded uranium. This is accomplished by melting the uranium in contact with either thorium oxide, maguesium oxide, alumnum oxide, beryllium oxide, or uranium dioxide. The melting is preferably carried out at from 1150 deg to 1400 deg C in an inert atmosphere, such as argon or helium. During this treatment a scale of uranium dioxide forms on the uranium whtch contains most of the fission products.

Feder, H.M.; Chellew, N.R.

1958-02-01

178

Process for uranium separation and preparation of UOâ. 2NHâ. 2HF. [Effluents from UFâ. -->. UOâ conversion  

Microsoft Academic Search

A process for treating the aqueous effluents that are produced in converting gaseous UFâ (uranium hexafluoride) into solid UOâ (uranium dioxide) by way of an intermediate (NHâ)â UOâ (COâ)â (''AUC'' Compound) is disclosed. These effluents, which contain large amounts of NHâ\\/sup +\\/, COâ\\/sup 2 -\\/, F⁻, and a small amount of U are mixed with HâSOâ (sulfuric acid) in order

Dokuzoguz

1976-01-01

179

Functional sorbents for selective capture of plutonium, americium, uranium, and thorium in blood.  

PubMed

Self-assembled monolayer on mesoporous supports (SAMMS) are hybrid materials created from attachment of organic moieties onto very high surface area mesoporous silica. SAMMS with surface chemistries including three isomers of hydroxypyridinone, diphosphonic acid, acetamide phosphonic acid, glycinyl urea, and diethylenetriamine pentaacetate (DTPA) analog were evaluated for chelation of actinides ((239)Pu, (241)Am, uranium, thorium) from blood. Direct blood decorporation using sorbents does not have the toxicity or renal challenges associated with traditional chelation therapy and may have potential applications for critical exposure cases, reduction of nonspecific dose during actinide radiotherapy, and for sorbent hemoperfusion in renal insufficient patients, whose kidneys clear radionuclides at a very slow rate. Sorption affinity (K(d)), sorption rate, selectivity, and stability of SAMMS were measured in batch contact experiments. An isomer of hydroxypyridinone (3,4-HOPO) on SAMMS demonstrated the highest affinity for all four actinides from blood and plasma and greatly outperformed the DTPA analog on SAMMS and commercial resins. In batch contact, a fifty percent reduction of actinides in blood was achieved within minutes, and there was no evidence of protein fouling or material leaching in blood after 24 h. The engineered form of SAMMS (bead format) was further evaluated in a 100-fold scaled-down hemoperfusion device and showed no blood clotting after 2 h. A 0.2 g quantity of SAMMS could reduce 50 wt.% of 100 ppb uranium in 50 mL of plasma in 18 min and that of 500 dpm mL(-1) in 24 min. 3,4-HOPO-SAMMS has a long shelf-life in air and at room temperature for at least 8 y, indicating its feasibility for stockpiling in preparedness for an emergency. The excellent efficacy and stability of SAMMS materials in complex biological matrices suggest that SAMMS can also be used as orally administered drugs and for wound decontamination. By changing the organic groups of SAMMS, they can be used not only for actinides but also for other radionuclides. By using the mixture of these SAMMS materials, broad spectrum decorporation of radionuclides is very feasible. PMID:20699706

Yantasee, Wassana; Sangvanich, Thanapon; Creim, Jeffery A; Pattamakomsan, Kanda; Wiacek, Robert J; Fryxell, Glen E; Addleman, R Shane; Timchalk, Charles

2010-09-01

180

Functional Sorbents for Selective Capture of Plutonium, Americium, Uranium, and Thorium in Blood  

PubMed Central

Self-assembled monolayer on mesoporous supports (SAMMS™) are hybrid materials created from attachment of organic moieties onto very high surface area mesoporous silica. SAMMS with surface chemistries including three isomers of hydroxypyridinone, diphosphonic acid, acetamide phosphonic acid, glycinyl urea, and diethylenetriamine pentaacetate (DTPA) analog were evaluated for chelation of actinides (239Pu, 241Am, uranium, thorium) from blood. Direct blood decorporation using sorbents does not have toxicity or renal challenges associated with traditional chelation therapy and may have potential applications for critical exposure cases, reduction of nonspecific dose during actinide radiotherapy, and for sorbent hemoperfusion in renal insufficient patients, whose kidney clear radionuclides at very slow rate. Sorption affinity (Kd), sorption rate, selectivity, and stability of SAMMS were measured in batch contact experiments. An isomer of hydroxypyridinone (3,4-HOPO) on SAMMS demonstrated the highest affinity for all four actinides from blood and plasma and greatly outperformed the DTPA analog on SAMMS and commercial resins. In batch contact, a fifty percent reduction of actinides in blood was achieved within minutes, and there was no evidence of protein fouling or material leaching in blood after 24 hr. The engineered form of SAMMS (bead format) was further evaluated in a 100-fold scaled-down hemoperfusion device and showed no blood clotting after 2 hr. A 0.2 g quantity of SAMMS could reduce 50 wt.% of 100 ppb uranium in 50 mL of plasma in 18 min and that of 500 dpm mL?1 in 24 min. 3,4-HOPO-SAMMS has a long shelf-life in air and at room temperature for at least 8 years, indicating its feasibility for stockpiling in preparedness for an emergency. The excellent efficacy and stability of SAMMS materials in complex biological matrices suggest that SAMMS can also be used as orally administered drugs and for wound decontamination. By changing the organic groups of SAMMS, they can be used not only for actinides but also for other radionuclides. By using the mixture of these SAMMS materials, broad spectrum decorporation of radionuclides is very feasible.

Yantasee, Wassana; Sangvanich, Thanapon; Creim, Jeffery A; Pattamakomsan, Kanda; Wiacek, Robert J; Fryxell, Glen E; Addleman, R Shane; Timchalk, Charles

2010-01-01

181

Substrate selectivity and inhibitor sensitivity affect xylanase functionality in wheat flour gluten–starch separation  

Microsoft Academic Search

Addition of xylanases (EC 3.2.1.8) that varied in their substrate selectivities and\\/or wheat xylanase inhibitor sensitivities in dough batter gluten–starch separation of wheat flour showed the importance of these enzyme characteristics for their functionality in this process. A xylanase from Aspergillus aculeatus (XAA) with selectivity for hydrolysis of water extractable arabinoxylan (WE-AX), which is not inhibited by wheat flour xylanase

Sofie A Frederix; Christophe M Courtin; Jan A Delcour

2004-01-01

182

New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations  

SciTech Connect

The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

Bartsch, Richard A.

2012-06-04

183

Advanced Uranium Enrichment Processes.  

National Technical Information Service (NTIS)

Three advanced Uranium enrichment processes are dealt with in the report: AVLIS (Atomic Vapour LASER Isotope Separation), MLIS (Molecular LASER Isotope Separation) and PSP (Plasma Separation Process). The description of the physical and technical features...

M. Clerc P. Plurien

1986-01-01

184

Air separation by single wall carbon nanotubes: Thermodynamics and adsorptive selectivity  

Microsoft Academic Search

Separation of a nitrogen-oxygen mixture (air) by single wall carbon nanotubes has been studied using grand canonical Monte Carlo simulations at a range of nanotube diameters, temperatures, and pressures. It is demonstrated that depending on these operating parameters, the extent of adsorptive selectivity can vary significantly. Detailed calculations are also presented for the adsorption isotherms, energies, and isosteric heats of

Gaurav Arora; Stanley I. Sandler

2005-01-01

185

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

186

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

187

Appraisal of Selected Epidemiologic Issues from Studies of Lung Cancer among Uranium and Hard Rock Miners.  

National Technical Information Service (NTIS)

An extensive body of published information about lung cancer among uranium miners was reviewed and diverse information, useful in identifying important issues but not in resolving them was found. Measuring exposure and response; thresholds of exposure; la...

G. R. Petersen L. E. Sever

1982-01-01

188

Modeling of the Microchemistry for Diffusion of Selected Impurities in Uranium.  

National Technical Information Service (NTIS)

Unalloyed metallic uranium used in some work done at Y-12 contains small quantities of impurities, the three most significant of which are carbon, ion, and silicon. During metallurgical processing, as the metallic matrix solution becomes supersaturated in...

J. R. Kirkpatrick J. S. Bullock

2001-01-01

189

Development of Electrically Switched Ion Exchange Process for Selective Ion Separations  

SciTech Connect

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

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

1999-05-03

190

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

191

Reanalysis of uranium toxicity data for selected freshwater organisms and the influence of dissolved organic carbon.  

PubMed

The present study reanalyzed 46 existing uranium (U) chronic toxicity datasets for four freshwater species to generate consistent toxicity measures and explore relationships between U toxicity and key physicochemical variables. Dissolved organic carbon (DOC) was consistently the best predictor of U toxicity based on 10% inhibitory concentration (IC10) and median inhibitory concentration (IC50) values, with water hardness also being a significant co-predictor of IC50 concentrations for one species. The influence of DOC on acute and chronic U toxicity was further characterized using existing data for five species, and was found to vary depending on species, DOC source, and exposure duration (acute vs chronic). The slopes of the relationships between DOC and (normalized) acute and chronic U toxicity were modeled using cumulative probability distributions. From these, slopes were selected for which to correct acute or chronic U toxicity values or hazard estimates based on the aquatic DOC concentration. The fifth percentiles of these cumulative probability distributions for acute and chronic exposure data were 0.064 and 0.090, respectively, corresponding to a 6.4 and 9.0% reduction in U toxicity relative to the toxicity at the base DOC concentration for each 1 mg/L increase in DOC concentration (over the DOC range 0-30 mg/L). Algorithms were developed to enable the adjustment of U toxicity values and U hazard estimates, depending on DOC concentrations. These algorithms will significantly enhance the environmental relevance of water quality/risk assessments for U in fresh surface waters. PMID:22893585

van Dam, R A; Trenfield, M A; Markich, S J; Harford, A J; Humphrey, C L; Hogan, A C; Stauber, J L

2012-09-07

192

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

193

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

194

Dissolution of Uranium and Vanadium from Aerodynamically Size-Separated Ore Particles in a Simulated Lung Fluid.  

National Technical Information Service (NTIS)

The purpose of the project was to gain some insight into the long-term clearance of particulate lung burdens. Quantitative relations were sought between the physical-chemical properties of uranium ore particles and their reported clearance from the lung. ...

O. R. Moss

1976-01-01

195

CATION EXCHANGE SEPARATION AND SPECTROPHOTOMETRIC DETERMINATION OF MICROGRAM AMOUNTS OF RHODIUM IN URANIUM-BASE FISSIUM ALLOYS  

Microsoft Academic Search

Uranium is extracted with 30% tributyl phosphate in carbon tetrachloride ; from a nitric acid solution of the fissium alloy which contains ursnium, ; molybdenum, ruthenium, palladium, and zirconium, and the raffinate is strongly ; fumed with perchloric acid. The solution is then passed through a Dowex 50W-X8 ; cation exchange resin. Palladium is eluted with 0.3M hydrochloric acid, and

J. O. Karttunen; H. B. Evans

1960-01-01

196

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

197

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

198

PROCESS OF RECOVERING URANIUM  

Microsoft Academic Search

A method is presented for separating and recovering uranium from a ; complex mixure of impurities. The uranium is dissolved to produce an aqueous ; acidic solution including various impurities. In accordance with one method, ; with the uranium in the uranyl state, hydrogen cyanide is introduced into the ; solution to complex the impurities. Subsequently, ammonia is added to

Kilner

1959-01-01

199

Development of a composite palladium membrane for selective hydrogen separation at high temperature  

SciTech Connect

In this paper a method is described for development of a composite palladium membrane for selective hydrogen separation at high temperature. Electroless plating is used to form a thin palladium film on a silver porous substrate. The composite formed showed excellent mechanical strength and very large selectivity for hydrogen. The studies performed so far suggest that electroless plating can be utilized in making a metal composite membrane that can be used at high temperatures. Composite properties seem fairly constant at high temperatures. The permeability of the composite membrane is comparable to theoretical permeabilities for pure palladium.

Govind, R.; Atnoor, D.

1991-03-01

200

CO 2\\/C 2H 6 separation using solubility selective membranes  

Microsoft Academic Search

Ethane can be a major component of natural gas, and it forms a maximum pressure azeotrope with carbon dioxide, which can hinder carbon dioxide removal if distillation is used. This paper describes a solubility selective membrane material for this separation. A crosslinked poly(ethylene oxide) [PEO] material [XLPEO] was prepared from a prepolymer solution containing 71wt.% poly(ethylene glycol) methyl ether acrylate

Scott Kelman; Haiqing Lin; Edgar S. Sanders; Benny D. Freeman

2007-01-01

201

Selection of ionic liquids as entrainers for separation of water and 2-propanol  

Microsoft Academic Search

A procedure for experimental evaluation of ionic liquids (ILs) as entrainers was proposed. For selection of ILs which can be potentially used for the separation of the azeotropic mixture of water and 2-propanol by extractive distillation, vapor–liquid equilibria were measured for ternary systems of water+2-propanol+IL at 100kPa. A previously presented ebulliometer was modified to improve the reliability of measurement of

Lianzhong Zhang; Jianzhi Han; Dongshun Deng; Jianbing Ji

2007-01-01

202

Selective separation of proteins with pH-dependent magnetic nanoadsorbents  

Microsoft Academic Search

Two kinds of unique pH-dependent magnetic nanoadsorbents based on silica coated magnetic nanoparticles (SMNPs) and amino-silica coated magnetic nanoparticles (ASMNPs) have been exploited for selective separation of proteins. With different isoelectric points, silica coated magnetic nanoadsorbents (SMNAs) and amino-silica coated magnetic nanoadsorbents (ASMNAs) can respectively adsorb proteins with different charges. The interactions between proteins and magnetic nanoadsorbents changed with the

Xiaoxiao He; Yingjie Chen; Kemin Wang; Ping Wu; Ping Gong; Hailing Huo

2007-01-01

203

Selective separation of germanium(IV) by 2,3-dihydroxypropyl chitosan resin  

Microsoft Academic Search

2,3-Dihydroxypropyl chitosan resin, prepared from chitosan and a 1,2-diol, adsorbed only germanium(IV) from aqueous solutions containing semimetals over the range of acidic to weakly basic media. The adsorption capacities of the chitosan resin were up to about 1.4mmolg?1. The selective separation of germanium(IV) from tellurium(VI) and boron was achieved with a column method using the chitosan resin. The breakthrough points

Yoshinari Inukai; Toyotaka Chinen; Toshio Matsuda; Yasuhiko Kaida; Seiji Yasuda

1998-01-01

204

Geological and geochemical aspects of uranium deposits: a selected, annotated bibliography  

SciTech Connect

A compilation of 490 references is presented which is the second in a series compiled from the National Uranium Resource Evaluation (NURE) Bibliographic Data Base. This data base is one of six created by the Ecological Sciences Information Center, Oak Ridge National Laboratory, for the Grand Junction Office of the Department of Energy. Major emphasis for this volume has been placed on uranium geology, encompassing deposition, genesis of ore deposits, and ore controls; and prospecting techniques, including geochemistry and aerial reconnaissance. The following indexes are provided to aid the user in locating references of interest: author, geographic location, quadrangel name, geoformational feature, taxonomic name, and keyword.

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

1978-06-01

205

Isotopic composition and origin of uranium and plutonium in selected soil samples collected in Kosovo  

Microsoft Academic Search

Soil samples collected from locations in Kosovo where depleted uranium (DU) ammunition was expended during the 1999 Balkan conflict were analysed for uranium and plutonium isotopes content (234U,235U,236U,238U,238Pu,239+240Pu). The analyses were conducted using gamma spectrometry (235U,238U), alpha spectrometry (238Pu,239+240Pu), inductively coupled plasma–mass spectrometry (ICP—MS) (234U,235U,236U,238U) and accelerator mass spectrometry (AMS) (236U). The results indicated that whenever the U concentration exceeded

P. R. Danesi; A. Bleise; W. Burkart; T. Cabianca; M. J. Campbell; M. Makarewicz; J. Moreno; C. Tuniz; M. Hotchkis

2003-01-01

206

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

207

Flame treatment for the selective wetting and separation of PVC and PET  

SciTech Connect

Flame treatment has been used for many years to modify the surface of plastics to allow coatings to be added. The effect of the treatment is to produce hydrophilic species on the surface of the plastic making it water-wettable. The production of hydrophilic plastic surfaces is also required in the selective separation of plastics by froth flotation. For the process to be selective one plastic must be rendered hydrophilic while another remains hydrophobic. In this study the potential for separation of PVC and PET has been investigated. Flame treatment was shown to be very effective in producing a hydrophilic surface on both plastics, although the process was not selective under the conditions investigated. Raising the temperature of the plastics above their softening point produced a hydrophobic recovery. As the softening point of PVC was significantly lower than for PET it was possible to produce a significant difference in hydrophobicity, as judged using contact angle measurement. When immersed in water the contact angle of the PVC was found to be strongly dependent on the pH. Good separation efficiency of the two plastics was achieved by froth flotation from pH 4 to 9. One particular advantage of the technique is that no chemical reagents may be required in the flotation stage. The practicalities of designing a flake treatment system however have to be addressed before considering it to be a viable industrial process.

Pascoe, R.D.; O'Connell, B

2003-07-01

208

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

209

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

210

Uranium geochemistry of selected rock units from the Marysvale Volcanic Field, Piute County, Utah  

SciTech Connect

The Marysvale Volcanic Field is an area rich in uranium. This study was undertaken to determine if the uranium deposits might be of volcanogenic origin. This geochemical study consisted of determining the major, minor and trace element concentrations of the major volcanic units, and the relationships of the rock chemistry to uranium mineralization. The units in the Marysvale Volcanic Field, consist of ash-flow tuffs, intermediate lava flows, and associated intrusives of the Bullion Canyon volcanics and ash-flow tuffs, volcaniclastic deposits, domes and stocks of the Mount Belknap volcanics. When compared to overlaying welded tuff or rhyolitic units, the vitrophyric samples from the Mount Belknap volcanic units, are all enriched in F, Cs, and U, and that 50% of the vitrophyres are enriched in Cr, Cu, Mo, Ni, Zr, Pb, Sr, V, and Zn. Overlying untis have been devitrified and have released U as well as other trace elements into the volcanogenic system. This study has reevaluated the Marysvale Central Mining District and has proposed another theory as to the origin of the uranium deposits in that area. This hypothesis places a previously unidentified caldera around the area, and this author has named it the Marysvale caldera. Evidence for this caldera includes: arcurate faults which surround the region; alteration patterns which appear to form a circular pattern along the boundary of the proposed caldera; the presence of small monzonite intrusive bodies appear to ring the caldera; the presence of ash-flow tuffs which thicken appreciably along the northeast boundary of the caldera; and the central intrusive which may represent a resurgent phase of the proposed caldera. This seems to be a viable alternative to the magmatic hydrothermal origin for the uranium deposits presently proposed for the Central Mining District.

Hoffer, R.L.

1982-01-01

211

Magnetoencephalogram blind source separation and component selection procedure to improve the diagnosis of Alzheimer's disease patients.  

PubMed

The aim of this study was to improve the diagnosis of Alzheimer's disease (AD) patients applying a blind source separation (BSS) and component selection procedure to their magnetoencephalogram (MEG) recordings. MEGs from 18 AD patients and 18 control subjects were decomposed with the algorithm for multiple unknown signals extraction. MEG channels and components were characterized by their mean frequency, spectral entropy, approximate entropy, and Lempel-Ziv complexity. Using Student's t-test, the components which accounted for the most significant differences between groups were selected. Then, these relevant components were used to partially reconstruct the MEG channels. By means of a linear discriminant analysis, we found that the BSS-preprocessed MEGs classified the subjects with an accuracy of 80.6%, whereas 72.2% accuracy was obtained without the BSS and component selection procedure. PMID:18003241

Escudero, Javier; Hornero, Roberto; Abásolo, Daniel; Fernández, Alberto; Poza, Jesús

2007-01-01

212

Selective separation of proteins with pH-dependent magnetic nanoadsorbents  

NASA Astrophysics Data System (ADS)

Two kinds of unique pH-dependent magnetic nanoadsorbents based on silica coated magnetic nanoparticles (SMNPs) and amino-silica coated magnetic nanoparticles (ASMNPs) have been exploited for selective separation of proteins. With different isoelectric points, silica coated magnetic nanoadsorbents (SMNAs) and amino-silica coated magnetic nanoadsorbents (ASMNAs) can respectively adsorb proteins with different charges. The interactions between proteins and magnetic nanoadsorbents changed with the solution pH. Thus, the adsorption or desorption between proteins and magnetic nanoadsorbents can be controlled by changing the solution pH according to the charge of the proteins. And the magnetic nanoadsorbents can be separated and recycled simply with a magnet. As model adsorbates, Cyt-c and BSA are selectively separated from simple protein mixtures with SMNAs and ASMNAs respectively. Cyt-c was adsorbed on SMNAs at pH 8.0 at 0.160 mg mg-1. And BSA was adsorbed on ASMNAs at pH 5.0 at 0.142 mg mg-1.

He, Xiaoxiao; Chen, Yingjie; Wang, Kemin; Wu, Ping; Gong, Ping; Huo, Hailing

2007-09-01

213

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

PubMed

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. PMID:24072040

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

2013-09-26

214

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

215

Corrosion of friction rock stabilizers in selected uranium and copper mine waters. Report of Investigations\\/1984  

Microsoft Academic Search

The Bureau of Mines evaluated corrosion resistance of Split Set friction rock stabilizer mine roof bolts to aid in better prediction of useful service life. Electrochemical corrosion testing was conducted utilizing an automated corrosion measurement system. Natural and\\/or synthetic mine waters from four uranium and two copper mines were the test media for the two types of high-strength, low-alloy (HSLA)

M. M. Tilman; A. F. Jolly; L. A. Neumeier

1984-01-01

216

Functional Sorbents for Selective Capture of Plutonium, Americium, Uranium, and Thorium in Blood  

Microsoft Academic Search

Nano-engineered solid sorbents for chelation of actinides (239Pu, 241Am, uranium, thorium) from human blood were developed and evaluated in vitro. These sorbents, known as the self-assembled monolayer on mesoporous supports (SAMMSTM), are hybrid materials created from attachment of organic moieties onto extremely high surface area mesoporous silica. The organic moieties known to be effective at capturing actinides including three isomers

Wassana Yantasee; Thanapon Sangvanich; Jeffrey A. Creim; Kanda Pattamakomsan; Robert J. Wiacek; Glen E. Fryxell; Raymond S. Addleman; Charles Timchalk

2010-01-01

217

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

218

New mechanism of recoil fractionation of uranium isotopes  

SciTech Connect

A number of extremely high /sup 234/U//sup 238/U activity ratios (up to 410 +/- 16) were observed in the uranium-poor acid-residues (and their chemical and physical separates) of various uranium ores from different locations on the world. For interpreting this kind of enrichment of /sup 234/U, a new mechanism of uranium isotopic fraction, referred to as poor-rich mechanism, was presented, which says that in a uranium-bearing system consisting of two phases, the uranium-poor phase becomes enriched in /sup 234/U and the uranium-rich phase depleted in /sup 234/U due to the ejection of recoil /sup 234/U atoms across the interface of the two phases; the recoil /sup 234/U atoms are then re-fixed firmly in new crystalline lattices due to self-annealing effect of recoil tracks; and when the two phases are separated by selective dissolution or other manners, enrichment of /sup 234/U in the uranium-poor phase (and depletion in the uranium-rich phase probably) will be observed. A set of mathematical equations expressing the new mechanism were derived. The recipes for extracting uranium fractions with high /sup 234/U//sup 238/U activity ratios from uranium ores were described. A complete classification of the factors responsible for uranium isotopic fractionation was presented. The direct ejection mechanism, preferential solution mechanism and poor-rich mechanism are three major mechanisms causing the uranium isotopic fractionation in nature. The range of recoil /sup 234/U atoms in uranium ore and the neutron fluence and conversion factor of Oklo natural reactor were estimated from the experimental data.

Sheng, Z.

1987-01-01

219

METHOD OF SEPARATING Pu FROM METATHESIZED BiPO$sub 4$ CARRIER  

DOEpatents

A process is given for separating uranium, neptunium, and/or plutonium from a bismuth hydroxide carrier by selective dissolution of these actinides with nitric acid of a concentration of from 0.05 to 0.5N.

Knox, W.J.; Thompson, S.G.

1960-05-31

220

Application of topological indexes for evaluation of the TLC separation of selected essential oil components.  

PubMed

The selected essential oil components (menthol, (+)bomeol, geraniol, linalool, carvone, camphor, (IR)-(-)fenchone) were separated by adsorption thin-layer chromatography using benzene as mobile phase. Investigated terpenes were characterized by selected topological indexes based on the adjacency and distance matrix. From among all the topological indexes counted only Si(o) index (the sum of the distance between the oxygen atom and all the remaining atoms in graph) as well as cluster Randi? indexes (4chi(c), and 4chi(v)c) allow for estimation of the chromatograms obtained. With the fact mentioned above, there exists the possibility of prediction of relative situation on a chromatogram of the terpenes investigated. For the rest of topological indexes that possibility was not stated. PMID:12365610

Pyka, Alina; Bober, Katarzyna; Gurak, Danuta; Niestroj, Anna

221

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

222

Upgrading of Low-Grade Manganese Ore by Selective Reduction of Iron Oxide and Magnetic Separation  

NASA Astrophysics Data System (ADS)

The utilization of low-grade manganese ores has become necessary due to the intensive mining of high-grade ores for a long time. In this study, calcined ferruginous low-grade manganese ore was selectively reduced by CO, which converted hematite to magnetite, while manganese oxide was reduced to MnO. The iron-rich component was then separated by magnetic separation. The effects of the various reduction parameters such as particle size, reduction time, temperature, and CO content on the efficiency of magnetic separation were studied by single-factor experiments and by a comprehensive full factorial experiment. Under the best experimental conditions tested, the manganese content in the ore increased from around 36 wt pct to more than 44 wt pct, and almost 50 wt pct of iron was removed at a Mn loss of around 5 pct. The results of the full factorial experiments allowed the identification of the significant effects and yielded regression equations for pct Fe removed, Mn/Fe, and pct Mn loss that characterize the efficiency of the upgrading process.

Gao, Yubo; Olivas-Martinez, M.; Sohn, H. Y.; Kim, Hang Goo; Kim, Chan Wook

2012-12-01

223

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

224

Sorption profile and chromatographic separation of uranium (VI) ions from aqueous solutions onto date pits solid sorbent.  

PubMed

The retention profile of uranium (VI) as uranyl ions (UO(2)(2+)) from the aqueous media onto the solid sorbent date pits has been investigated. The sorption of UO(2)(2+) ions onto the date pits was achieved quantitatively (98+/-3.4%, n=5) after 15 min of shaking at pH 6-7. The sorption of UO(2)(2+) onto the used sorbent was found fast, followed by a first order rate equation with an overall rate constant, k of 4.8+/-0.05 s(-1). The sorption data were explained in a manner consistent with a "solvent extraction" mechanism. The sorption data were also subjected to Freundlich isotherm model over a wide range of equilibrium concentration (1-20 microgmL(-1)) of UO(2)(2+). The results revealed that, a "dual-mode" of sorption mechanism involving absorption related to "solvent extraction" and an added component for "surface adsorption" is most likely operated simultaneously for uranyl ions uptaking the solid sorbent. The thermodynamic parameters (-DeltaH, DeltaS and DeltaG) of the uranyl ions uptake onto the date pits indicated that, the process is endothermic and proceeds spontaneously. The interference of some diverse ions on the sorption UO(2)(2+) from the aqueous media onto the date pits packed column was critically investigated and the data revealed quantitative collection of UO(2)(2+) at 5 mLmin(-1) flow rate. The retained UO(2)(2+) was recovered quantitatively with HCl (3.0 molL(-1)) from the column at 5 mLmin(-1) flow rate. The mode of binding of the date pits with UO(2)(2+) was determined from the IR spectral date bits before and after extraction of uranium (VI). The height equivalent (HETP) and the number (N) of theoretical plates of the date pits packed column were determined from the chromatograms. Complete retention and recovery of UO(2)(2+) spiked to wastewater samples by the date pits packed column was successfully achieved. The capacity of the used sorbent towards retention of uranium (VI) from aqueous solutions was much better than the most common sorbents. PMID:18761152

Saad, E M; Mansour, R A; El-Asmy, A; El-Shahawi, M S

2008-05-15

225

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

226

PROCESS OF RECOVERING URANIUM  

DOEpatents

A process is presented for recovering uranium values from calutron deposits. The process consists in treating such deposits to produce an oxidlzed acidic solution containing uranium together with the following imparities: Cu, Fe, Cr, Ni, Mn, Zn. The uranium is recovered from such an impurity-bearing solution by adjusting the pH of the solution to the range 1.5 to 3.0 and then treating the solution with hydrogen peroxide. This results in the precipitation of uranium peroxide which is substantially free of the metal impurities in the solution. The peroxide precipitate is then separated from the solution, washed, and calcined to produce uranium trioxide.

Carter, J.M.; Larson, C.E.

1958-10-01

227

URANIUM RECOVERY PROCESS  

DOEpatents

In the prior art processing of uranium ores, the ore is flrst digested with nitric acid and filtered, and the uranium values are then extracted tom the filtrate by contacting with an organic solvent. The insoluble residue has been processed separately in order to recover any uranium which it might contain. The improvement consists in contacting a slurry, composed of both solution and residue, with the organic solvent prior to filtration. Tbe result is that uranium values contained in the residue are extracted along with the uranium values contained th the solution in one step.

Yeager, J.H.

1958-08-12

228

Theoretical stability assessment of uranyl phosphates and apatites: selection of amendments for in situ remediation of uranium.  

PubMed

Addition of an amendment or reagent to soil/sediment is a technique that can decrease mobility and reduce bioavailability of uranium (U) and other heavy metals in the contaminated site. According to data from literature and results obtained in field studies, the general mineral class of apatites was selected as a most promising amendment for in situ immobilization/remediation of U. In this work we presented theoretical assessment of stability of U(VI) in four apatite systems (hydroxyapatite (HAP), North Carolina Apatite (NCA), Lisina Apatite (LA), and Apatite II) in order to determine an optimal apatite soil amendment which could be used for in situ remediation of uranium. In this analysis we used a theoretical criterion which is based on calculation of the ion-ion interaction potential, representing the main term of the cohesive energy of the matrix/pollutant system. The presented results of this analysis indicate (i) that the mechanism of immobilization of U by natural apatites depends on their chemical composition and (ii) that all analyzed apatites represent, from the point of view of stability, promising materials which could be used in field remediation of U-contaminated sites. PMID:15885755

Raicevic, S; Wright, J V; Veljkovic, V; Conca, J L

2006-02-15

229

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

230

Isotopic composition and origin of uranium and plutonium in selected soil samples collected in Kosovo.  

PubMed

Soil samples collected from locations in Kosovo where depleted uranium (DU) ammunition was expended during the 1999 Balkan conflict were analysed for uranium and plutonium isotopes content (234U, 235U, 236U, 238U, 238Pu, (239 + 240)Pu). The analyses were conducted using gamma spectrometry (235U, 238U), alpha spectrometry (238Pu, (239 + 240)Pu), inductively coupled plasma-mass spectrometry (ICP-MS) (234U, 235U, 236U, 238U) and accelerator mass spectrometry (AMS) (236U)). The results indicated that whenever the U concentration exceeded the normal environmental values (approximately 2 to 3 mg/kg) the increase was due to DU contamination. 236U was also present in the released DU at a constant ratio of 236U (mg/kg)/238U (mg/kg) = 2.6 x 10(-5), indicating that the DU used in the ammunition was from a batch that had been irradiated and then reprocessed. The plutonium concentration in the soil (undisturbed) was about 1 Bq/kg and, on the basis of the measured 238Pu/(239 + 240)Pu, could be entirely attributed to the fallout of the nuclear weapon tests of the 1960s (no appreciable contribution from DU). PMID:12500799

Danesi, P R; Bleise, A; Burkart, W; Cabianca, T; Campbell, M J; Makarewicz, M; Moreno, J; Tuniz, C; Hotchkis, M

2003-01-01

231

Assessment of the Quality of Selected EIA Data Series: Uranium and Nuclear Power Data from 1977 to 1983.  

National Technical Information Service (NTIS)

This report focuses on uranium exploration activity, uranium marketing activity, and capacity factors for nuclear power plants. These topics represented EIA's major data collections in the nuclear power area at the time this study was prepared. At the tim...

R. Miller L. E. Doman S. R. Freedman

1985-01-01

232

Preliminary Study of the Favorability for Uranium in Selected Areas in the Basin and Range Province, Nevada.  

National Technical Information Service (NTIS)

Six uranium areas in Nevada were examined in a reconnaissance fashion to determine their favorability for uranium deposits. The favorable areas are: Virgin Valley, Humboldt County; northern Reese River Valley, Lander County; East Walker River, Lyon County...

G. M. Cupp K. D. Kiloh R. C. Horton S. H. Leedom T. P. Mitchell

1977-01-01

233

Selective separation of benzene from hydrocarbon mixtures via liquid–liquid extraction method using aqueous solutions of substituted cyclodextrins  

Microsoft Academic Search

The selective separation of benzene from hydrocarbon mixtures was investigated by way of liquid–liquid extraction using aqueous solutions of unsubstituted ?-cyclodextrin (?CD), ?CD and seven kinds of substituted CDs. Separation factor for benzene to cyclohexane was evaluated from the extraction of an equimolar mixture of benzene and cyclohexane. Hydroxypropyl-?CD showed the highest selectivity followed by 2,6-di-O-methyl-?CD, hydroxyethyl-?CD, hydroxypropyl-?CD and 2,6-di-O-methyl-?CD.

Isamu Uemasu; Satoshi Kushiyama

2004-01-01

234

Pervaporation study on the dehydration of aqueous butanol solutions: a comparison of flux vs. permeance, separation factor vs. selectivity  

Microsoft Academic Search

Dehydration of four butanol isomers from their aqueous solutions by pervaporation was studied using a commercial hydrophilic membrane with feed water concentration less 20wt% at 60°C to 100°C. The effects of feed water content on membrane separation performance were studied in terms of: (1) fluxes and permeances of individual components, and (2) separation factor and selectivity of water to butanol.

Wei Fen Guo; Tai-Shung Chung; Takeshi Matsuura

2004-01-01

235

Separation of hydrogen isotopes by selective adsorption with production of high-purity DT and T sub 2  

Microsoft Academic Search

Selective adsorption on a solid at 20 K provides the means to separate hydrogen isotopes, and particularly to purify small quantities of molecular D--T or produce pure {ital J}=1 Tâ for nuclear spin polarization. We develop adsorption isotherms and separation factors for several solids from literature data. Our computational model of adsorption column operation, developed to determine column sensitivity to

J. L. Maienschein; R. S. Hudson; R. T. Tsugawa; E. M. Fearon; P. C. Souers; G. W. Collins

1992-01-01

236

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 (Ms = 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

2013-08-27

237

Electrochemical reduction of porous 17 kg uranium oxide pellets by selection of an optimal cathode\\/anode surface area ratio  

Microsoft Academic Search

This study examines how the cathode\\/anode surface area ratio affects the electrochemical reduction of uranium oxide in a molten Li2O–LiCl electrolyte. A bench-scale test showed that a low cathode\\/anode surface area ratio is helpful for efficiently attaining a high current density and producing metallic uranium from uranium oxide in an Li2O–LiCl electrolyte. A 17kg uranium oxide electrolysis cell was set

Eun-Young Choi; Jin-Mok Hur; In-Kyu Choi; Seon Gil Kwon; Dae-Seung Kang; Sun Seok Hong; Ho-Sup Shin; Min A. Yoo; Sang Mun Jeong

2011-01-01

238

Uranium removal from soils: An overview from the Uranium in Soils Integrated Demonstration program  

SciTech Connect

An integrated approach to remove uranium from uranium-contaminated soils is being conducted by four of the US Department of Energy national laboratories. In this approach, managed through the Uranium in Soils Integrated Demonstration program at the Fernald Environmental Management Project, Fernald, Ohio, these laboratories are developing processes that selectively remove uranium from soil without seriously degrading the soil`s physicochemical characteristics or generating waste that is difficult to manage or dispose of. These processes include traditional uranium extractions that use carbonate as well as some nontraditional extraction techniques that use citric acid and complex organic chelating agents such as naturally occurring microbial siderophores. A bench-scale engineering design for heap leaching; a process that uses carbonate leaching media shows that >90% of the uranium can be removed from the Fernald soils. Other work involves amending soils with cultures of sulfur and ferrous oxidizing microbes or cultures of fungi whose role is to generate mycorrhiza that excrete strong complexers for uranium. Aqueous biphasic extraction, a physical separation technology, is also being evaluated because of its ability to segregate fine particulate, a fundamental requirement for soils containing high levels of silt and clay. Interactions among participating scientists have produced some significant progress not only in evaluating the feasibility of uranium removal but also in understanding some important technical aspects of the task.

Francis, C.W. [Oak Ridge National Lab., TN (United States); Brainard, J.R.; York, D.A. [Los Alamos National Lab., NM (United States); Chaiko, D.J. [Argonne National Lab., IL (United States); Matthern, G. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1994-09-01

239

Rapid and selective separation for mixed proteins with thiol functionalized magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; p I = 4.65) and lysozyme (LYZ; 14.3 kDa; p I = 11) were shown at the pH values corresponding to their own p I in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein.

Lee, Soo Youn; Ahn, Chi Young; Lee, Jiho; Lee, Jin Hyung; Chang, Jeong Ho

2012-05-01

240

Filter paper with selective absorption and separation of liquids that differ in surface tension.  

PubMed

Superhydrophobic and superoleophilic filter paper was successfully prepared by treating commercially available filter paper with a mixture of hydrophobic silica nanoparticles and polystyrene solution in toluene. Applications of the filter paper in separating liquids with low surface tensions such as oil and ethanol from water were investigated in detail. The oil uptake ability of the superhydrophobic filter paper was evaluated and the results show that the filter paper can selectively adsorb oil floating on a water surface or in aqueous emulsions. Furthermore, filtration of mixtures of oil and water through the paper can reduce the water content in the oil. Additionally, the filter paper can also extract ethanol from homogeneous aqueous solution. PMID:20356268

Wang, Suhao; Li, Mei; Lu, Qinghua

2010-03-01

241

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.

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

2010-01-01

242

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

243

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

244

Determination of SCFAs in water using GC-FID. Selection of the separation system.  

PubMed

In the present study, an analytical procedure was developed for the determination of short-chain fatty acids (SCFAs) in landfill leachate and municipal wastewater employing injection of aqueous samples to gas chromatograph with flame ionization detector (GC-FID). Chromatographic conditions such as a separation system, injection volume, oven temperature program were investigated and selected. With two columns, one with a polar (polyethylene glycol) and one with a non-polar (dimethylpolisiloxane) stationary phase, good separation of SCFAs, containing from 2 to 8 carbon atoms, was achieved. The sample volume was 2 ?L and the temperature program 80°C (30 s) then 7 °C min(-1) to 220 °C (2 min). LOQs values were below 0.25 mg L(-1). The concentrations of the acids in the landfill leachate studied ranged from 0.45±0,059 (average ± extended uncertainty) mg L(-1) for pentanoic acid to 15.2±0.73 mg L(-1) for ethanoic acid. Concentrations of SCFAs in the municipal wastewater were lower than LOQs. PMID:22284873

Banel, Anna; Jakimska, Anna; Wasielewska, Marta; Wolska, Lidia; Zygmunt, Bogdan

2011-03-05

245

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 A? 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

246

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

PubMed

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 A 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. PMID:16512731

Arora, Gaurav; Sandler, Stanley I

2006-02-28

247

Separation of metals by supported liquid membrane  

Microsoft Academic Search

This patent describes a process of separating a preselected chemical species selected from the group consisting of aluminum, arsenic, antimony, bismuth, cadmium, chromium, copper, cobalt, gallium, gold, hafnium, indium, iridium, iron, lead, manganese, mercury, molybdenum, neodymium, nickel, niobium, osmium, palladium, platinum, rhenium, rhodium, ruthenium, selenium, silver, tantalum, tellurium, thallium, thorium, tin, tungsten, uranium, vanadium, zinc, or zirconium from a feedstream.

Takigawa

1992-01-01

248

Laser isotope separation: the plutonium connection  

SciTech Connect

A new process that promises to enrich uranium more cheaply and easily than either of the technologies currently used is described. The new process, called laser isotope separation (LIS), uses lasers to selectively excite and ionize uranium-235 and then accumulates that isotope on collectors. The advantages of the LIS process are discussed. It is concluded that the government's growing support of the laser isotope separation process may reconnect civilian nuclear power to the military requirements for enough plutonium for 14,000 new warheads.

Palmer, G.; Bolef, D.I.

1984-03-01

249

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

250

PRODUCTION OF URANIUM METAL BY CARBON REDUCTION  

DOEpatents

The preparation of uranium metal by the carbon reduction of an oxide of uranium is described. In a preferred embodiment of the invention a charge composed of carbon and uranium oxide is heated to a solid mass after which it is further heated under vacuum to a temperature of about 2000 deg C to produce a fused uranium metal. Slowly ccoling the fused mass produces a dendritic structure of uranium carbide in uranium metal. Reacting the solidified charge with deionized water hydrolyzes the uranium carbide to finely divide uranium dioxide which can be separated from the coarser uranium metal by ordinary filtration methods.

Holden, R.B.; Powers, R.M.; Blaber, O.J.

1959-09-22

251

Air separation by single wall carbon nanotubes: Thermodynamics and adsorptive selectivity  

NASA Astrophysics Data System (ADS)

Separation of a nitrogen-oxygen mixture (air) by single wall carbon nanotubes has been studied using grand canonical Monte Carlo simulations at a range of nanotube diameters, temperatures, and pressures. It is demonstrated that depending on these operating parameters, the extent of adsorptive selectivity can vary significantly. Detailed calculations are also presented for the adsorption isotherms, energies, and isosteric heats of pure nitrogen, oxygen, and their mixture at 100 K in a carbon nanotube of 12.53-A? diameter. In single-component simulations, it is found that near saturation loading nitrogen forms only an annular layer close to the nanotube wall, while smaller-sized oxygen also occupies the region near the center of the nanotube. In mixture adsorption, the energetically favored nitrogen is preferentially adsorbed at low loadings. However, at high loadings oxygen replaces nitrogen due to the dominant entropic effects, and therefore a high selectivity towards oxygen is observed close to the saturation loading. The effect of the entropic change on mixture adsorption is evident from the calculated isosteric heats of adsorption. The mixture isotherms obtained from simulations are found to be in good agreement with the predictions based only on the pure component simulation results.

Arora, Gaurav; Sandler, Stanley I.

2005-07-01

252

Air separation by single wall carbon nanotubes: thermodynamics and adsorptive selectivity.  

PubMed

Separation of a nitrogen-oxygen mixture (air) by single wall carbon nanotubes has been studied using grand canonical Monte Carlo simulations at a range of nanotube diameters, temperatures, and pressures. It is demonstrated that depending on these operating parameters, the extent of adsorptive selectivity can vary significantly. Detailed calculations are also presented for the adsorption isotherms, energies, and isosteric heats of pure nitrogen, oxygen, and their mixture at 100 K in a carbon nanotube of 12.53-A diameter. In single-component simulations, it is found that near saturation loading nitrogen forms only an annular layer close to the nanotube wall, while smaller-sized oxygen also occupies the region near the center of the nanotube. In mixture adsorption, the energetically favored nitrogen is preferentially adsorbed at low loadings. However, at high loadings oxygen replaces nitrogen due to the dominant entropic effects, and therefore a high selectivity towards oxygen is observed close to the saturation loading. The effect of the entropic change on mixture adsorption is evident from the calculated isosteric heats of adsorption. The mixture isotherms obtained from simulations are found to be in good agreement with the predictions based only on the pure component simulation results. PMID:16095382

Arora, Gaurav; Sandler, Stanley I

2005-07-22

253

Tuning the gate opening pressure of Metal-Organic Frameworks (MOFs) for the selective separation of hydrocarbons.  

PubMed

Separation of hydrocarbons is one of the most energy demanding processes. The need to develop materials for the selective adsorption of hydrocarbons, under reasonable conditions, is therefore of paramount importance. This work unveils unexpected hydrocarbon selectivity in a flexible Metal-Organic Framework (MOF), based on differences in their gate opening pressure. We show selectivity dependence on both chain length and specific framework-gas interaction. By combining Raman spectroscopy and theoretical van der Waals Density Functional (vdW-DF) calculations, the separation mechanisms governing this unexpected gate-opening behavior are revealed. PMID:22946693

Nijem, Nour; Wu, Haohan; Canepa, Pieremanuele; Marti, Anne; Balkus, Kenneth J; Thonhauser, Timo; Li, Jing; Chabal, Yves J

2012-09-10

254

Iron EDTA chelate catalyzed oxidation of uranium  

Microsoft Academic Search

Uranium ore deposits which contain uranium in the relatively insoluble tetravalent state are readily selectively leached in situ to recover relatively pure uranium compounds, by: (A) passing through the ore deposit a relatively dilute aqueous leach solution of ammonium bicarbonate, ferric ammonium ethylenediaminetetraacetic acid (EDTA), and a source of oxygen, the leach solution converting the tetravalent uranium to hexavalent uranium

J. F. Jackovitz; A. J. Panson; E. A. Pantier

1981-01-01

255

Atomic vapor laser isotope separation  

SciTech Connect

Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power reactor fuel has been under development for over 10 years. In June 1985 the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for the internationally competitive production of uranium separative work. The economic basis for this decision is considered, with an indicated of the constraints placed on the process figures of merit and the process laser system. We then trace an atom through a generic AVLIS separator and give examples of the physical steps encountered, the models used to describe the process physics, the fundamental parameters involved, and the role of diagnostic laser measurements.

Stern, R.C.; Paisner, J.A.

1985-11-08

256

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

257

Production of separation-nozzle systems for uranium enrichment by a combination of X-ray lithography and galvanoplastics  

Microsoft Academic Search

X-ray lithography using synchrotron radiation has been applied in a multi-step process for the production of plastic moulds to be used in the fabrication of separation nozzles by electrodeposition. For characteristic dimensions of a few microns a total height of the nozzle structure of about 400 µm has been achieved. Structural details of about 0.1 µm are being reproduced across

E. W. Backer; W. Ehrfeld; D. Münchmeyer; H. Betz; A. Heuberger; S. Pongratz; W. Glashauser; H. J. Michel; R. Siemens

1982-01-01

258

USE OF RADIOMETRIC METHODS FOR THE SIMULTANEOUS SEPARATE DETERMINATION OF URANIUM, THORIUM, RADIUM AND POTASSIUM IN ACID IGNEOUS ROCKS  

Microsoft Academic Search

A method has been worked out for the simultaneous separate determination ; of U, Th, Ra, and K in acid igneous rocks. Samples of artificial mixtures have ; been investigated containing 6 x 10⁻⁴% of U, 18 x 10⁻⁴ % of The, 2 x ; 10⁻¹°% of Ra and 9% of K (almost an order less than in Eldjurta granites).

A. S. Serdyukova; Yu. T. Kapitanov

1958-01-01

259

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

260

METHOD FOR RECOVERING URANIUM FROM OILS  

DOEpatents

A method is presented for recovering uranium from hydrocarbon oils, wherein the uranium is principally present as UF/sub 4/. According to the invention, substantially complete removal of the uranium from the hydrocarbon oil may be effected by intimately mixing one part of acetone to about 2 to 12 parts of the hydrocarbon oil containing uranium and separating the resulting cake of uranium from the resulting mixture. The uranium in the cake may be readily recovered by burning to the oxide.

Gooch, L.H.

1959-07-14

261

Separation and detection of rare cells in a microfluidic disk via negative selection.  

PubMed

Cyto-analysis of rare cells often requires separation and detection with each procedure posing substantial challenges. This paper presents a disk-based microfluidic platform for both procedures via an immunomagnetic negative selection process. The microfluidic platform's unique features include a multistage magnetic gradient to trap labeled cells in double trapping areas, drainage of fluid to substantially shorten detection time, and a bin-like regions to capture target cells to facilitate a seamless enumeration process. Proof-of-concept was conducted using MCF7 as target rare cells (stained with anti-cytokeratin-FITC antibodies) spiked into Jurkat Clone E6-1 non-target cells (labeled with anti-CD45-PE and anti-PE BD magnetic beads). Then, mononuclear cells (MNC) from healthy blood donors were mixed with MCF7s, modeling rare cells, and tested in the disk. Results show a non-linear magnetic coupling effect of the multistage magnet substantially increased the trapping efficacy over that of a single magnet, contributing to the depletion rate of Jurkats, which reaches 99.96%. Detection time is extensively shortened by depletion of 95% of non-cell-containing fluid in the collection area. The average yield of detected MCF7 cells is near-constant 60 ± 10% over a wide range of rarity from 10(-3) to 10(-6) and this yield also holds for the MCF7/MNC complex mixture. Comparison with autoMACS and BD IMagnet separators revealed the average yield from the disk (60%) is superior to that of autoMACS (37.3%) and BD IMagnet (48.3%). The advantages of near-constant yield, roughly 30 min of operation, an acceptable level of cell loss, and potentially low cost system should aid in cyto-analysis of rare cells. PMID:21088774

Chen, Chen-Lin; Chen, Ken-Chao; Pan, Yu-Cheng; Lee, Tai-Ping; Hsiung, Lo-Chang; Lin, Cheng-Ming; Chen, Chang-Yu; Lin, Ching-Hung; Chiang, Bor-Luen; Wo, Andrew M

2010-11-18

262

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

263

Prospects for uranium enrichment  

Microsoft Academic Search

It is pointed out that the lack of suitable lasers constitutes the biggest technological barrier to practical laser techniques for the enrichment of uranium isotopes. Costs of laser isotope-separation techniques are compared with those of other approaches, taking into account as a basis conservative extrapolations of existing laser technology. Attention is given to the demand for enriched uranium, the types

R. J. Jensen; J. G. Marinuzzi; C. P. Robinson; S. D. Rockwood

1976-01-01

264

Separation and immobilization of lipase from Penicillium simplicissimum by selective adsorption on hydrophobic supports.  

PubMed

Lipases are an enzyme class of a great importance as biocatalysts applied to organic chemistry. However, it is still necessary to search for new enzymes with special characteristics such as good stability towards high temperatures, organic solvents, and high stereoselectivity presence. The present work's aim was to immobilize the lipases pool produced by Penicillium simplissicimum, a filamentous fungi strain isolated from Brazilian babassu cake residue. P. simplissicimum lipases were separated into three different fractions using selective adsorption method on different hydrophobic supports (butyl-, phenyl-, and octyl-agarose) at low ionic strength. After immobilization, it was observed that these fractions' hyperactivation is in the range of 131% to 1133%. This phenomenon probably occurs due to enzyme open form stabilization when immobilized onto hydrophobic supports. Those fractions showed different thermal stability, specificity, and enantioselectivity towards some substrates. Enantiomeric ratio for the hydrolysis of (R,S) 2-O-butyryl-2-phenylacetic acid ranged from 1 to 7.9 for different immobilized P. simplissicimum lipase fractions. Asymmetry factor for diethyl 2-phenylmalonate hydrolysis ranged from 11.8 to 16.4 according to the immobilized P. simplissicimum lipase fractions. Those results showed that sequential adsorption methodology was an efficient strategy to obtain new biocatalysts with different enantioselectivity degrees, thermostability, and specificity prepared with a crude extract produced by a simple and low-cost technology. PMID:19037600

Cunha, Aline G; Fernández-Lorente, Gloria; Gutarra, Melissa L E; Bevilaqua, Juliana V; Almeida, Rodrigo V; Paiva, Lúcia M C; Fernández-Lafuente, Roberto; Guisán, Jose M; Freire, Denise M G

2008-11-28

265

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

266

Photochemical isotope separation  

DOEpatents

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

1987-01-01

267

Laser isotope separation  

DOEpatents

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Munich, DE); Boyer, Keith (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM)

1988-01-01

268

Laser isotope separation  

DOEpatents

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.

1975-11-26

269

Photochemical isotope separation  

DOEpatents

A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

1987-04-28

270

PREPARATION OF URANIUM-ALUMINUM ALLOYS  

DOEpatents

A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

Moore, R.H.

1962-09-01

271

Molecular modeling of selectivity of single-walled carbon nanotube and MCM-41 for separation of methane and carbon dioxide  

Microsoft Academic Search

Separation of carbon dioxide and methane in cylindrical geometries materials (including MCM-41 and single-walled carbon nanotube (SWNT)) is investigated systematically using grand canonical Monte Carlo (GCMC) simulations. The selectivities of carbon dioxide with respect to methane (CO2\\/CH4) in MCM-41 and SWNT at different temperatures and mole fractions are obtained. Simulation results indicate that the selectivity of MCM-41 for CO2\\/CH4 is

Xiang Zhang; Xiaohong Shao; Wenchuan Wang; Dapeng Cao

2010-01-01

272

Multilayer composite membranes for gas separation based on crosslinked PTMSP gutter layer and partially crosslinked Matrimid ® 5218 selective layer  

Microsoft Academic Search

New multilayer composite membranes for gas separation with enhanced performance were prepared. Membranes consist of poly[1-(trimethylsilyl)-1-propyne] (PTMSP) as the gutter layer deposited on a poly(acrylonitrile) porous support and partially crosslinked Matrimid® 5218 selective top-layer. Matrimid® 5218 is an attractive soluble polyimide known for its excellent thermal and mechanical resistance and high selectivities for some gas pairs, e.g. O2\\/N2 or H2\\/CH4.

J. Peter; K.-V. Peinemann

2009-01-01

273

Supporting and Improving Sellafield Purex Operations: Recent Work on Reductive Plutonium-Uranium Separations Using Ferrous Sulphamate and Hydroxylamine  

SciTech Connect

The separation of plutonium in spent fuel processing through reductive stripping is a very well established technology. Although a very effective reagent for reductive stripping of Pu, Ferrous Sulphamate (FeSM) adds significantly to non-evaporable salt-bearing effluent, a situation exacerbated due to its super-stoichiometric consumption in the process. The process chemistry which leads to excessive ferrous consumption - commonly termed the 'box effect' - is a complex interplay of chemical reactions and mass transfer. We have developed a chemical model to describe the 'box effect' and incorporated it within powerful solvent extraction process models to describe and replicate the process in a counter-current mixer-settler battery at plant and laboratory scale. The chemical and process models have been validated against lab-scale experimental and plant operational data and can, therefore, be used to help justify flowsheet changes and examine a range of mal-operation scenarios to support continued operation of the plant. A programme of work to partially replace the FeSM feed with hydroxylamine (HAN) and thereby reduce waste arisings is well advanced. Laboratory and modelling work has furthered our understanding of the complex process chemistry of the Pu/Fe/HAN system, and flowsheet testing has shown that Fe/HAN reductive stripping can be as efficient as FeSM only stripping. Flowsheet trials on a glovebox-housed miniature mixer-settler rig have been undertaken to validate process models of a U/Pu split contactor operating under FeSM only, mixed FeSM/HAN conditions and mal-operation conditions. (authors)

Fox, O.D.; Mason, C.; Taylor, R.J.; Woodhead, D. [Nexia Solutions Ltd., Sellafield, Seascale, CA20 1PG (United Kingdom); Hobbs, J.; Rebello, A. [British Nuclear Group, Sellafield, Seascale, CA20 1PG (United Kingdom)

2006-07-01

274

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

275

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).

2013-01-01

276

Novel biphasic separations utilising highly selective molecularly imprinted polymers as biorecognition solvent extraction agents.  

PubMed

Molecularly imprinted polymers (MIPs) represent a class of artificial receptors that promise an environmentally robust alternative to naturally occurring biorecognition elements of biosensing devices and systems. However, in general, the performance of conventional MIPs in aqueous environments is poor. In the study reported here, this limitation has been addressed by the novel application of MIPs as a solvent extraction solid phase in a biphasic solvent system. This paper describes a previously unreported use of MIPs as solvent extraction reagents, their successful application to aqueous sample media and the opportunities for utilisation of this unique system in novel biosensing and separation procedures. This study demonstrates the development of a novel biphasic solvent system utilising MIP in the extracting phase to enhance both efficiency and selectivity of a simple two phase liquid extraction. Monodisperse propranolol imprinted polymer microspheres [p(divinylbenzene-co-methacrylic acid)] were prepared by precipitation polymerisation. Initially, the affinity of the polymers for (R,S)-propranolol was assessed by established techniques whereby the MIP demonstrated greater affinity for the template than did the non-imprinted control polymer (NIP). Importantly, MIP performance was also assessed using the novel dual solvent system. The depletion of (R,S)-propranolol from the aqueous phase into the polymer containing organic phase was determined. When compared to control extractions containing no polymer the presence of MIP in the extracting solvent phase resulted in an increased extraction of (R,S)-propranolol from the aqueous phase. Importantly, this extraction was significantly greater in the presence of MIP when compared to NIP. This unique principle generates opportunities for MIP based extractions and chemical enrichments in industrial applications, offering commercial, ecological and practical advantages to traditional solvent extraction techniques. The technique is readily transferable to analytical microsystems utilising MIP recognition elements generating promising opportunities for MIP based sensing of aqueous sample media. PMID:16938448

Castell, Oliver K; Allender, Christopher J; Barrow, David A

2006-08-30

277

Rationally tuned micropores within enantiopure metal-organic frameworks for highly selective separation of acetylene and ethylene  

SciTech Connect

Separation of acetylene and ethylene is an important industrial process because both compounds are essential reagents for a range of chemical products and materials. Current separation approaches include the partial hydrogenation of acetylene into ethylene over a supported Pd catalyst, and the extraction of cracked olefins using an organic solvent; both routes are costly and energy consuming. Adsorption technologies may allow separation, but microporous materials exhibiting highly selective adsorption of C{sub 2}H{sub 2}/C{sub 2}H{sub 4} have not been realized to date. Here, we report the development of tunable microporous enantiopure mixed-metal-organic framework (M'MOF) materials for highly selective separation of C{sub 2}H{sub 2} and C{sub 2}H{sub 4}. The high selectivities achieved suggest the potential application of microporous M'MOFs for practical adsorption-based separation of C{sub 2}H{sub 2}/C{sub 2}H{sub 4}.

Xiang, Sheng-Chang [University of Texas at San Antonio (UTSA); Zhang, Zhangjing [University of Texas at San Antonio (UTSA); Zhao, Cong-Gui [University of Texas at San Antonio (UTSA); Hong, Kunlun [ORNL; Zhao, Xuebo [University of Newcastle upon Tyne; Ding, De-Rong [University of Texas at San Antonio (UTSA); Xie, Ming-Hua [University of Texas, Pan American, Edinburg, TX; Wu, Chuan-De [University of Texas, Pan American, Edinburg, TX; Madhab, Das [University of Texas at San Antonio (UTSA); Gill, Rachel [University of Newcastle upon Tyne; Thomas, K Mark [University of Newcastle upon Tyne; Chen, Banglin [University of Texas at San Antonio (UTSA)

2011-01-01

278

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

279

Selective separation of chromium (VI) from acidic solutions containing various metal ions through emulsion liquid membrane using trioctylamine as extractant  

Microsoft Academic Search

Chromium compounds have received considerable attention because of used extensively in such industrial applications as electroplating, tanning of leather goods, steelmaking, and corrosion inhibition. In this work, selective separation and concentration of Cr (VI) ions from acidic solutions containing various metal ions through emulsion liquid membrane (ELM) containing trioctylamine (TOA) as extractant was studied. The membrane phase consists of kerosene

Recep Ali Kumbasar

2008-01-01

280

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...

281

Properties of poly-aminophenylboronate coatings in capillary electrophoresis for the selective separation of diastereoisomers and glycoproteins.  

PubMed

The polymerisation of 3-aminophenylboronic acid (APBA) in aqueous environment has been used for the open tubular modification of capillary electrophoresis (CE) capillaries. Being poly-APBA endowed with boronic acid, aromatic rings and secondary amines groups, it posses a variety of functional groups affecting selectivity. Diastereoisomers (e.g. ascorbic and isoascorbic acid) and proteins (e.g. haemoglobins) were successfully separated onto poly-APBA column, by means of a combination of electrophoresis and open tubular electrochromatography. The mechanism of selection was investigated: results indicate an interplay between enhancing or silencing the contribution of the protonable functionalities (amino groups, boronic acid). The properties of APBA polymer coating make it attractive for CE separation and for further application in affinity separations and chip technologies. PMID:14753696

Bossi, Alessandra; Castelletti, Laura; Piletsky, Sergey A; Turner, Anthony P F; Righetti, Pier Giorgio

2004-01-16

282

Self-Report Measures of Parent-Adolescent Attachment and Separation-Individuation: A Selective Review.  

ERIC Educational Resources Information Center

|Reviews and critiques three self-report measures of parent-adolescent attachment (Parental Bonding Instrument, Parental Attachment Questionnaire, Inventory of Parent and Peer Attachment) and three self-report measures of parent-adolescent separation-individuation (Psychological Separation Inventory, Personal Authority in the Family System…

Lopez, Frederick G.; Gover, Mark R.

1993-01-01

283

The psychological adjustment of children from separated families: The role of selected social support variables  

Microsoft Academic Search

This study investigates the impact of social support on children's psychological adjustment following the divorce of their parents. Seventy-one (71) children from separated families and 120 children from intact families participated in the study. Data were collected twice. Children from separated families listed support networks of lower density with more sitters and teachers contributing both to emotional support and to

Camil Bouchard; Sylvie Drapeau

1991-01-01

284

ASPECTS OF MULTICOMPONENT MIXTURE SEPARATION IN THE PRESENCE OF SELECTIVE SOLVENTS  

Microsoft Academic Search

The extractive and autoextractive distillation of ternary and quaternary azeotropic solvent mixtures was adopted to demonstrate the relation between the structure of phase diagram of the azeotropic systems and the operating parameters of the extractive distillation column based on the relative volatility criterion. A set of separation schemes belonging to different structural classes have been investigated. The separation scheme that

H. Benyounes; A. K. Frolkova

2010-01-01

285

A SIMPLE PARAMETER FOR SELECTING AN ADSORBENT FOR GAS SEPARATION BY PRESSURE SWING ADSORPTION  

Microsoft Academic Search

A simple parameter is proposed for comparing the performance of two or more adsorbents for a particular binary gas separation by pressure swing adsorption. The parameter is most suitable for separations based on differences in equilibrium adsorption capacity rather than on differences in adsorption kinetics. The two main components of the parameter are the ratio of the delta loadings (differences

Salil U. Rege; Ralph T. Yang

2001-01-01

286

Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Remedial action selection report  

SciTech Connect

The uranium mill tailings site near Durango, Colorado, was one of 24 inactive uranium mill sites designated to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). Part of the UMTRCA requires that the US 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 US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which has been developed to serve a two-fold purpose. First, it describes the activities that have been conducted by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium mill processing site near Durango, Colorado. Secondly, this document and the rest of the RAP, upon concurrence and execution by the DOE, the State of Colorado, and the NRC, become Appendix B of the Cooperative Agreement between the DOE and the State of Colorado.

Not Available

1991-12-01

287

Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Remedial action selection report. Revised final report  

SciTech Connect

The uranium mill tailings site near Durango, Colorado, was one of 24 inactive uranium mill sites designated to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). Part of the UMTRCA requires that the US 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 US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which has been developed to serve a two-fold purpose. First, it describes the activities that have been conducted by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium mill processing site near Durango, Colorado. Secondly, this document and the rest of the RAP, upon concurrence and execution by the DOE, the State of Colorado, and the NRC, become Appendix B of the Cooperative Agreement between the DOE and the State of Colorado.

Not Available

1991-12-01

288

Evaluation of selected detector systems for products formed in the atmospheric hydrolysis of uranium hexafluoride  

SciTech Connect

Sensitive detection of UF/sub 6/ hydrolysis products, either by discontinuous sampling or by continuous or near real-time monitoring, is an important safety consideration for DOE contractors handling large quantities of UF/sub 6/. Automated continuous or rapid intermittent remote sensing of these reaction products can provide an alarm signal when a preselected threshold value has been exceeded (absolute response) or when a significant emission excursion has occurred (rate of change of response). This report evaluates the performance of selected devices for the detection of airborne materials formed in the release of liquid UF/sub 6/ (approx. =1.3 g) into an enclosed volume of 6 m/sup 3/; these experiments were initiated on October 23, 1986. The detection principles investigated are: photometric, gas detector tubes, and electrochemical sensor.

Bostick, W.D.; Bostick, D.T.

1987-03-01

289

URANIUM EXTRACTION  

DOEpatents

The recovery of uranium values from uranium ore such as pitchblende is described. The ore is first dissolved in nitric acid, and a water soluble nitrate is added as a salting out agent. The resulting feed solution is then contacted with diethyl ether, whereby the bulk of the uranyl nitrate and a portion of the impurities are taken up by the ether. This acid ether extract is then separated from the aqueous raffinate, and contacted with water causing back extractioa of the uranyl nitrate and impurities into the water to form a crude liquor. After separation from the ether extract, this crude liquor is heated to about 118 deg C to obtain molten uranyl nitrate hexahydratc. After being slightly cooled the uranyl nitrate hexahydrate is contacted with acid free diethyl ether whereby the bulk of the uranyl nitrate is dissolved into the ethcr to form a neutral ether solution while most of the impurities remain in the aqueous waste. After separation from the aqueous waste, the resultant ether solution is washed with about l0% of its volume of water to free it of any dissolved impurities and is then contacted with at least one half its volume of water whereby the uranyl nitrate is extracted into the water to form an aqueous product solution.

Harrington, C.D.; Opie, J.V.

1958-07-01

290

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

291

Line Selection and Parameter Optimization for Trace Analysis of Uranium in Glass Matrices by Laser-Induced Breakdown Spectroscopy (LIBS).  

PubMed

Laser-induced breakdown spectroscopy (LIBS) has been evaluated for the determination of uranium in real-world samples such as uraninite. NIST Standard Reference Materials were used to evaluate the spectral interferences on detection of uranium. The study addresses the detection limit of LIBS for several uranium lines and their relationship to non-uranium lines, with emphasis on spectral interferences. The data are discussed in the context of optimizing the choice of emission lines for both qualitative and quantitative analyses from a complex spectrum of uranium in the presence of other elements. Temporally resolved spectral emission intensities, line width, and line shifts were characterized to demonstrate the parameter influence on these measurements. The measured uranium line width demonstrates that LIBS acquired with moderately high spectral resolution (e.g., by a 1.25 m spectrometer with a 2400 grooves/mm grating) can be utilized for isotope shift measurements in air at atmospheric pressure with single to tens of parts per million (ppm) level detection limits, as long as an appropriate transition is chosen for analysis. PMID:24160879

Choi, Inhee; Chan, George C-Y; Mao, Xianglei; Perry, Dale L; Russo, Richard E

2013-11-01

292

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

293

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

2013-06-06

294

National Uranium Resource Evaluation: Durango Quadrangle, Colorado  

Microsoft Academic Search

The Durango Quadrangle (2°), Colorado, was evaluated using National Uranium Resource Evaluation criteria to determine environments favorable for uranium deposits. General reconnaissance, geologic and radiometric investigations, was augmented by detailed surface examination and radiometric and geochemical studies in selected areas. Eight areas favorable for uranium deposits were delineated. Favorable geologic environments include roscoelite-type vanadium-uranium deposits in the Placerville and Barlow

N. J. Theis; M. E. Madson; G. C. Rosenlund; W. R. Reinhart; H. A. Gardner

1981-01-01

295

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

1997-03-01

296

A microporous metal-organic framework for highly selective separation of acetylene, ethylene, and ethane from methane at room temperature.  

PubMed

A novel three-dimensional microporous metal-organic framework Zn(4)L(DMA)(4) (UTSA-33, H(8) L=1,2,4,5-tetra(5-isophthalic acid)benzene, DMA=N,N'-dimethylacetamide) with small pores of about 4.8 to 6.5 Å was synthesized and structurally characterized as a non-interpenetrated (4,8)-connected network with the flu topology (Schläfli symbol: (4(12)6(12)8(4))(4(6))(2)). The activated UTSA-33a exhibits highly selective separation of acetylene, ethylene, and ethane from methane with the adsorption selectivities of 12 to 20 at 296 K, which has been established exclusively by the sorption isotherms and simulated breakthrough experiments, thus methane can be readily separated from their binary and even ternary mixtures at room temperature. PMID:22162259

He, Yabing; Zhang, Zhangjing; Xiang, Shengchang; Fronczek, Frank R; Krishna, Rajamani; Chen, Banglin

2011-12-08

297

Study on the Perm-Selectivity of Thin Pd-Cu-Ni Ternary Alloy Membrane for Hydrogen Purification and Separation  

NASA Astrophysics Data System (ADS)

In order to meet the requirements of industries dealing with hydrogen, the membranes for hydrogen purification and separation need to be improved for both hydrogen permeability and selectivity. However, it has been difficult to enhance both properties simultaneously because their properties were contrary to each other. In this study, we fabricated a Pd-alloy membrane by using micro-polishing of porous metal support, plasma surface treatment, Pd-Cu sputtering at high temperature, and Cu-reflow process, and achieved both high permeability [10-6 mol/(m2\\cdots\\cdotPa)] and infinite selectivity. This Pd-Cu-Ni ternary alloy membrane could be commercialized for the purification and separation of hydrogen in various applications.

Kim, Dong-Won; Park, Yong Joon; Woo, Byung-Il; Kang, Seung-Min; Park, Jong-Soo

2010-01-01

298

Transfer and the Part-Time Student: The Gulf Separating Community Colleges and Selective Universities  

ERIC Educational Resources Information Center

|When representatives from community colleges and selective four-year institutions gather, there is no greater flashpoint than the topic of part-time enrollment. This issue--that students coming from an institution comprising mostly part-time students should be enabled to transfer to selective four-year institutions in which full-time enrollment…

Handel, Stephen J.

2009-01-01

299

Experimental and modeling of selective separation of gold(III) ions from aqueous solutions by emulsion liquid membrane system  

Microsoft Academic Search

Selective separation of gold(III) ions from acidic aqueous solutions, using MIBK as carrier and LK-80 as emulsifier, has been investigated. The extraction results from model solution containing Au3+, Pd2+, Pt4+, Cu2+ and Fe3+, showed that only the Au3+ ions transported across the liquid membrane and nearly all of other ions remained in the external solution without change in their concentration.

Ali Kargari; Tahereh Kaghazchi; Baharak Mardangahi; Mansoureh Soleimani

2006-01-01

300

Optimum Conditions of Separation Selectivity Based on Molecularly Imprinted Polymers of Bovine Serum Albumin Formed on Surface of Aminosilica  

Microsoft Academic Search

Sol-gel molecularly imprinted polymers for recognition of bovine serum albumin were prepared via polymerization on the surface of aminopropyl silica followed by immobilization proteins. Based on the above system, the relationship between fundamental parameters of preparation of molecularly imprinted polymers and their effect on the separation selectivity was studied. A mixture of octyltrimethoxysilane, 3-aminopropylsilane, and tetraethoxysilane at 42.5:42.5:5:15 was polymerized

Xue ZHOU; Xi-Wen HE; Lang-Xing CHEN; Wen-You LI; Yu-Kui ZHANG

2009-01-01

301

Chemistry, spectroscopy, and isotope-selective infrared photochemistry of volatile uranium compound tailored for 10-. mu. m absorption: U(OCH/sub 3/)/sub 6/  

SciTech Connect

This contribution reports on the chemical, vibrational spectroscopic, and infrared multiphoton photochemical properties of uranium hexamethoxide, U(OCH/sub 3/)/sub 6/, a prototype molecule for laser-induced uranium isotope separation with a carbon dioxide laser. Uranium hexamethoxide can be prepared from UCl/sub 4/ by conversion to Li/sub 2/U(OCH/sub 3/)/sub 6/, followed by oxidation with lead tetraacetate. Vapor pressure studies on U(OCH/sub 3/)/sub 6/ indicate that at 33/sup 0/C, the vapor pressure is 17 mtorr. The vibrational spectra of U(/sup 16/OCH/sub 3/)/sub 6/ and U(/sup 18/OCH/sub 3/)/sub 6/ have been assigned by using infrared and laser Raman data. Under idealized O/sub h/ symmetry, the U(/sup 16/OCH/sub 3/)/sub 6/ U-O stretching fundamentals are assigned at 505.0 (A/sub lg/), 464.8(T/sub 1u/, and 414.0 cm/sup -1/ (E/sub g/). Tentative assignments are also made for several of the overtone and combination transitions evidence for possible lowering of the symmetry is presented. In gas-phase infrared photochemical experiments, the predominant U(OCH/sub 3/)/sub 6/ photoproducts isolated are U(OCH/sub 3/)/sub 5/, methanol, and formaldhyde. These are suggestive of multiphoton U-O bond homolysis to produce uranium pentamethoxide and methoxy radicals. The enrichment of unreacted U(OCH/sub 3/)/sub 6/ in /sup 235/U is maximum at ca 927 cm/sup -1/ (near what may be a U-O stretching overtone transition) and exhibits both a low fluence threshold and diminution at high fluence.

Cuellar, E.A.; Miller, S.S.; Marks, T.J.; Weitz, E.

1983-07-13

302

Chemistry, spectroscopy, and isotope-selective infrared photochemistry of a volatile uranium compound tailored for 10-mm absorption: U(OCH/sub 3/)/sub 6/  

SciTech Connect

This contribution reports on the chemical, vibrational spectroscopic, and infrared multiphoton photochemical properties of uranium hexamethoxide, U(OCH/sub 3/)/sub 6/, a prototype molecule for laser-induced uranium isotope separation with a carbon dioxide laser. Uranium hexamethoxide can be prepared from UCl/sub 4/ by conversion to Li/sub 2/U(OCH/sub 3/)/sub 6/, followed by oxidation with lead tetraacetate. Vapor pressure studies on U(OCH/sub 3/)/sub 6/ indicate that ..delta..H/sub sub//sup 0/ = 23 +/- 3 kcal/mol and ..delta..S/sub sub//sup 0/ = 76 +/- 4 eu; at 33/sup 0/C, the vapor pressure is 17 mtorr. The vibrational spectra of U(/sup 16/OCH/sub 3/)/sub 6/ and U(/sup 18/OCH/sub 3/)/sub 6/ have been assigned by using infrared and laser Raman data. Under idealized O/sub h/ symmetry, the U(/sup 16/OCH/sub 3/)/sub 6/U-O stretching fundamentals are assigned at 505.0 (A/sub 1g/), 464.8 (T/sub 1u/), and 414.0 cm/sup -1/ (E/sub g/). Tentative assignments are also made for several of the overtone and combination transitions evidence for possible lowering of the symmetry is presented. In gas-phase infrared photochemical experiments, the predominant U(OCH/sub 3/)/sub 6/ photoproducts isolated are U(OCH/sub 3/)/sub 5/, methanol, and formaldehyde. These are suggestive of multiphoton U-O bond homolysis to produce uranium pentamethoxide and methoxy radicals. The enrichment of unreacted U(OCH/sub 3/)/sub 6/ in /sup 235/U is maximum at ca. 927 cm/sup -1/ (near what may be a U-O stretching overtone transition) and exhibits both a low fluence threshold and dimunution at high fluence.

Cuellar, E.A.; Miller, S.S.; Marks, T.J.; Weitz, E.

1983-07-13

303

Method of recovering uranium  

SciTech Connect

Uranium is recovered from a carbonate leach solution containing a dissolved uranium salt and a monovalent ion. The pH of the leach solution is adjusted to about 5 to about 7.5, and preferably to about 6 to about 7. Phosphate ion is then added to typical in-situ leach solutions in an amount from about 10 to about 30 mole % in excess of the amount needed to stoichiometrically react with the uranium in said solution. This results in the precipitation of a compound made up of the monovalent ion, uranium, and the phosphate ion, which is insoluble in the solution. The precipitate is then separated from the solution preferably by means of a centrifuge or a vortex clarifier. It can then be dissolved in acid, and the uranium extracted into an organic solvent such as DEHPA-TOPA in kerosene.

Camp, F.E.; Swartzlander, A.B.

1984-10-09

304

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

PubMed

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

2013-03-20

305

Comparative ease of separation of mixtures of selected nuisance anions (nitrate, nitrite, sulfate, phosphate) using Octolig®  

Microsoft Academic Search

Mixtures of sodium salts of nitrate, nitrite, sulfate, and phosphate were prepared in relative amounts present in atomic waste containers with a view to effect removal by chromatography over Octolig®, commercially available material with polyethylenediamine moieties covalently attached to high-surface area silica gel. Separation was attempted using aqueous solutions and column chromatography with Octolig®. It is presumed that this material

Frederick W. Stull; Dean F. Martin

2009-01-01

306

A model to optimize the selectivity of gas separation in membranes  

Microsoft Academic Search

We present a model of olefin\\/paraffin separation via nanocomposite membranes and a corresponding lattice kinetic Monte Carlo simulation. Our model is based on the solution-diffusion theory of facilitated transport through microporous membranes and the preferential binding of olefins to silver ions and nanoparticles. In our model, olefin molecules bind to the randomly distributed traps on a lattice whereas paraffin molecules

Zachary D. Pozun; Graeme Henkelman

2010-01-01

307

Temperature dependence of acidity constants, a tool to affect separation selectivity in capillary electrophoresis  

Microsoft Academic Search

The mathematical models of migration and dispersion in capillary zone electrophoresis of small molecules form a sound basis for separation strategies of complex mixtures. It turned out that the key property is the effective mobility of the sample ions. To tune resolution parameters such as pH, complexation constants and ionic strength are widely used; temperature however is not although mobilities

Jetse C. Reijenga; Leonardo G. Gagliardi; Ernst Kenndler

2007-01-01

308

SEPARATION OP ZIRCONIUM \\/IV\\/ FROM HAFNIUM \\/IV\\/ ON VARIOUS TYPES OF SELECTIVE ION-EXCHANGERS  

Microsoft Academic Search

Results of the studies on separation of hefnium \\/IV\\/ from zirconium \\/IV\\/ by frontal analysis on chelating ion-exchangers of different types have been presented. The phosphonic ion-exchanger Duolite ES-63 proved to be the best in zirconium sulphate purification from hafnium \\/IV\\/ among the examined chelating ion-exchangers.

Z. HUBICKI

1988-01-01

309

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  

Microsoft Academic Search

A very effective sorbent material which exhibits exceptional capture of hexavalent uranium from other actinides and lanthanides at ?gg?1 level, features pyridine 2,6-dimethanol immobilized onto alumina. The maximum sorption capacity for dioxouranium(VI) was found as 1.96mmolg?1 at pH 3.0. The adsorbed uranium complex was eluted completely by 0.05molL?1 (NH4)2CO3 solution and the concentration of hexavalent dioxouranium ion was monitored spectrophotometrically

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

2010-01-01

310

Geological and geochemical aspects of uranium deposits: a selected, annotated bibliography. Vol. 2, Rev. 1. [490 references  

SciTech Connect

This bibliography, a compilation of 490 references, is the second in a series compiled from the National Uranium Resource Evaluation (NURE) Bibliographic Data Base. This data base is one of six data bases created by the Ecological Sciences Information Center, Oak Ridge National Laboratory, for the Grand Junction Office of the Department of Energy. Major emphasis for this volume has been placed on uranium geology, encompassing deposition, genesis of ore deposits, and ore controls; and prospecting techniques, including geochemistry and aerial reconnaissance. The following indexes are provided to aid the user in locating references of interest: author, geographic location, quadrangle name, geoformational feature, taxonomic name, and keyword.

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

1979-07-01

311

A selective lon-exchange separation and spectrophotometric determination of traces of copper in silicate rocks  

Microsoft Academic Search

Summary  A combined cation-exchange separation-spectrophotometric procedure has been worked out for the accurate determination of traces\\u000a of copper in silicate rocks. Silicates are opened up with sulfuric and hydrofluoric acids. The residue is taken up into a\\u000a 0.5 M hydrochloric acid ?0.05 M oxalic acid ?1% hydrogen peroxide solution and loaded on a strongly acidic cation-exchange\\u000a resin column. Polyvalent ions including

R. Kuroda; T. Seki

1980-01-01

312

Selective Separation of Gallium from Acidic Leach Solutions by Emulsion Liquid Membranes  

Microsoft Academic Search

The separation and concentration of gallium from acidic leach solutions, containing various other ions such as iron, cobalt, nickel, zinc, cadmium, lead, copper, and aluminium, by an emulsion liquid membrane (ELM) technique using tributyl phosphate (TBP) as carrier has been presented. Liquid membrane consists of a diluent, a surfactant (ECA 4360J), and an extractant (TBP), and 0.1 M HCl or 0.1 M

R. A. Kumbasar; O. Tutkun

2006-01-01

313

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

314

Comparison of separation selectivity in aqueous and non-aqueous capillary electrophoresis  

Microsoft Academic Search

The use of non-aqueous capillary electrophoresis in free solution in uncoated fused-silica capillaries was investigated and compared with capillary electrophoresis using aqueous systems. Cationic drug substances differing only in the amine functionallity or even having the same charge-to-mass ratio were used as test solutes. Some of these test substances are difficult to separate in plain aqueous buffers and even when

Inga Bjørnsdottir; Steen HonoréHansen

1995-01-01

315

POMS Membrane for Selective Separation of Ethanol From Dilute Alcohol-Aqueous Solutions by Pervaporation  

Microsoft Academic Search

Lignocellulosic biomass has potential as an alternative to corn as starting material for the production of ethanol for the development of non-fossil fuel energy sources. In this case, low concentration bioethanol is gained by yeast fermentation and it has to be efficiently recovered and concentrated. For this purpose pervaporation separation of dilute alcohol-aqueous solutions was carried out using a poly(octhylmethyl

M. Lazarova; P. Bösch; A. Friedl

2012-01-01

316

BASIC PEROXIDE PRECIPITATION METHOD OF SEPARATING PLUTONIUM FROM CONTAMINANTS  

DOEpatents

A process is described for the separation from each other of uranyl values, tetravalent plutonium values and fission products contained in an aqueous acidic solution. First the pH of the solution is adjusted to between 2.5 and 8 and hydrogen peroxide is then added to the solution causing precipitation of uranium peroxide which carries any plutonium values present, while the fission products remain in solution. Separation of the uranium and plutonium values is then effected by dissolving the peroxide precipitate in an acidic solution and incorporating a second carrier precipitate, selective for plutonium. The plutonium values are thus carried from the solution while the uranium remains flissolved. The second carrier precipitate may be selected from among the group consisting of rare earth fluorides, and oxalates, zirconium phosphate, and bismuth lihosphate.

Seaborg, G.T.; Perlman, I.

1959-02-10

317

Selectivity in reversed-phase separations Influence of the stationary phase.  

PubMed

The selectivity difference between 15 different stationary phases was measured using a large number of analytes at 2 or 3 different pH values (3, 7 and 10) with acetonitrile and methanol as the mobile phase modifiers. The packings discussed include standard C(8) and C(18) packings, packings with embedded polar groups, a phenyl packing, a pentafluoro-phenyl packing, an adamantylethyl packing and others. The major selectivity differences observed are discussed in detail. Specific effects such as pi-pi interactions on phenyl packings or hydrogen-bond interactions on phases with embedded polar groups are confirmed. PMID:16806238

Neue, Uwe D; O'Gara, John E; Méndez, Alberto

2006-06-27

318

Selected values of chemical thermodynamic properties: compounds of uranium, protactinium, thorium, actinium, and the alkali metals. Final report  

SciTech Connect

This publication contains tables of recommended values for the standard enthalpies (heats) of formation, Gibbs (free) energies of formation, entropies, enthalpy contents and heat capacities at 298.15 K, and enthalpies of formation at O K for compounds of uranium, protactinium, thorium, actinium, lithium, sodium, potassium, rubidium, cesium, and francium.

Wagman, D.D.; Evans, W.H.; Parker, V.B.; Schumm, R.H.; Nuttall, R.L.

1981-05-01

319

Synthesis of surface imprinted nanospheres for selective removal of uranium from simulants of Sambhar salt lake and ground water.  

PubMed

Imprinted polymer nanospheres for uranium were prepared by complexing uranyl ion on to quinoline-8-ol functionalized 3-aminopropyltrimethoxysilane modified silica nanoparticles followed by surface imprinting with 4-VP (4-vinyl pyridine), HEMA (2-hydroxy ethyl methacrylate) and EGDMA (ethylene glycol dimethacrylate) as the functional monomers and cross linking agent respectively with AIBN (2,2'-azo-bis-isobutyronitrile) as initiator and 2-methoxyethanol as the porogen. Non-imprinted polymer material was also prepared under similar conditions omitting uranyl ion. The above materials were used for solid phase extraction of uranium. Recent realization that its chemical toxicity is dominant than radiation hazards makes decontamination a relevant topic for environmental point of view, particularly in the light of projected global thrust for uranium fuel based atomic power plants. The material offers high retention capacity of 97.1 ?mol g(-1) for 10 mg L(-1) of uranium that does not require tedious grinding and sieving steps, is water compatible and works in the pH range of 5-7, making it ideal for possible use in decontamination of polluted natural water samples or front end effluents of nuclear power reactors. PMID:21345587

Milja, Thazhathuparambil Elias; Prathish, Krishnapillai Padmajakumari; Prasada Rao, Talasila

2011-02-04

320

Selected values of chemical thermodynamic properties: compounds of uranium, protactinium, thorium, actinium, and the alkali metals. Final report  

Microsoft Academic Search

This publication contains tables of recommended values for the standard enthalpies (heats) of formation, Gibbs (free) energies of formation, entropies, enthalpy contents and heat capacities at 298.15 K, and enthalpies of formation at O K for compounds of uranium, protactinium, thorium, actinium, lithium, sodium, potassium, rubidium, cesium, and francium.

D. D. Wagman; W. H. Evans; V. B. Parker; R. H. Schumm; R. L. Nuttall

1981-01-01

321

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

322

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

SciTech Connect

Implementation of a closed loop nuclear fuel cycle requires the utilization of Pu-containing MOX fuels with the important side effect of increased production of the transplutonium actinides, most importantly isotopes of Am and Cm. Because the presence of these isotopes significantly impacts the long-term radiotoxicity of high level waste, it is important that effective methods for their isolation and/or transmutation be developed. Furthermore, since transmutation is most efficiently done in the absence of lanthanide fission products (high yield species with large thermal neutron absorption cross sections) it is important to have efficient procedures for the mutual separation of Am and Cm from the lanthanides. The chemistries of these elements are nearly identical, differing only in the slightly stronger strength of interaction of trivalent actinides with ligand donor atoms softer than O (N, Cl-, S). Research being conducted around the world has led to the development of new reagents and processes with considerable potential for this task. However, pilot scale testing of these reagents and processes has demonstrated the susceptibility of the new classes of reagents to radiolytic and hydrolytic degradation. In this project, separations of trivalent actinides from fission product lanthanides have been investigated in studies of 1) the extraction and chemical stability properties of a class of soft-donor extractants that are adapted from water-soluble analogs, 2) the application of water soluble soft-donor complexing agents in tandem with conventional extractant molecules emphasizing fundamental studies of the TALSPEAK Process. This research was conducted principally in radiochemistry laboratories at Washington State University. Collaborators at the Radiological Processing Laboratory (RPL) at the Pacific Northwest National Laboratory (PNNL) have contributed their unique facilities and capabilities, and have supported student internships at PNNL to broaden their academic experience. New information has been developed to qualify the extraction potential of a class of pyridine-functionalized tetraaza complexants indicating potential single contact Am-Nd separation factors of about 40. The methodology developed for characterization will find further application in our continuing efforts to synthesize and characterize new reagents for this separation. Significant new insights into the performance envelope and supporting information on the TALSPEAK process has also been developed.

Kenneth L. Nash

2009-09-22

323

Design of linear ligands for selective separation using a genetic algorithm applied to molecular architecture.  

PubMed

Continuous purification of chemical reaction products through adsorption-based operations during workup may present advantages over batch chromatography or crystallization. In pharmaceutical syntheses, however, the desired product is often structurally similar to byproducts or unconverted reactant, so that identifying a suitable adsorption medium is challenging. We developed an in silico screening process to design organic ligands which, when chemically bound to a solid surface, would constitute an effective adsorption for a pharmaceutically relevant mixture of reaction products. This procedure employs automated molecular dynamics simulations to evaluate potential ligands, by measuring the difference in adsorption energy of two solutes which differed by one functional group. Then, a genetic algorithm was used to iteratively improve a population of such ligands through selection and reproduction steps. This procedure identified chemical designs of the surface-bound ligands that were outside the set we considered using chemical intuition. The ligand designs achieved selectivity by exploiting phenyl-phenyl stacking which was sterically hindered in the case of one solution component. The ligand designs had selectivity energies of 0.8-1.6 kcal/mol in single-ligand, solvent-free simulations, if entropic contributions to the relative selectivity are neglected. We believe this molecular evolution technique presents a useful method for the directed exploration of chemical space or for molecular design, when the chemical properties of interest can be efficiently evaluated through simulations. PMID:23844994

Santiso, Erik E; Musolino, Nicholas; Trout, Bernhardt L

2013-07-11

324

Separating the effects of mutation and selection in producing DNA skew in bacterial chromosomes  

Microsoft Academic Search

BACKGROUND: Many bacterial chromosomes display nucleotide asymmetry, or skew, between the leading and lagging strands of replication. Mutational differences between these strands result in an overall pattern of skew that is centered about the origin of replication. Such a pattern could also arise from selection coupled with a bias for genes coded on the leading strand. The relative contributions of

Richard A Morton; Brian R Morton

2007-01-01

325

Selectivity Principles in Anion Separation by Crystallization of Hydrogen-Bonding Capsules  

SciTech Connect

The fundamental factors controlling anion selectivity in the crystallization of hydrogen-bonding capsules [Mg(H2O)6][X L2] (X = SO42-, 1a; SeO42-, 1b; SO32-, 1c; CO32-, 1d; L = tris[2-(3-pyridylurea)ethyl]-amine) from water have been investigated by solution and solid-state thermodynamic measurements, anion competition experiments, and X-ray structural analysis. The crystal structures of 1a-d are isomorphous, thereby simplifying the interpretation of the observed selectivities based on differences in anion coordination geometries. The solubilities of 1a-d in water follow the order: 1a < 1b < 1c < 1d, which is consistent with the selectivity for the tetrahedral sulfate and selenate anions observed in competitive crystallization experiments. Crystallization of the capsules is highly exothermic, with the most favorable {Delta}H{sub cryst}{sup o} of -99.1 and -108.5 kJ/mol corresponding to SO42- and SeO42-, respectively, in agreement with the X-ray structural data showing shape complementarity between these tetrahedral anions and the urea-lined cavities of the capsules. Sulfite, on the other hand, has a significantly less negative {Delta}H{sub cryst}{sup o} of -64.6 kJ/mol, which may be attributed to its poor fit inside the capsules, involving repulsive interactions. The more favorable entropy of crystallization for this anion, however, partly offsets the enthalpic disadvantage, resulting in a solubility product very similar to that of the selenate complex. Because of their very similar shape and size, SO42- and SeO42- have a propensity to form solid solutions, which limits the selectivity between these two anions in competitive crystallizations. In the end, a comprehensive picture of contributing factors to anion selectivity in crystalline hydrogen-bonding capsules emerges.

Custelcean, Radu [ORNL; Bock, Aurelien [ORNL; Moyer, Bruce A [ORNL

2010-01-01

326

Separate and shared sources of dual-task cost in stimulus identification and response selection.  

PubMed

There is often strong interference if a second target stimulus (T2) is presented before processing of a prior target stimulus (T1) is complete. In the "Psychological Refractory Period" (PRP) paradigm, responses are speeded and interference manifests as increased response time for T2. In the "Attentional Blink" (AB) paradigm, stimuli are masked and responses unspeeded; interference manifests as reduced T2 accuracy. While different causes have usually been considered for PRP and AB phenomena, recent evidence has supported a unified account based on a single, shared restriction on concurrent processing. Here we show that a full assessment of separate and shared resource limitations requires direct comparison of hybrid PRP/AB trials with corresponding pure PRP and AB cases. Randomizing trial types in such a comparison also brings substantial benefit in addressing possible changes in task preparation or readiness. The data from two such experiments--combining speeded auditory (SA) and unspeeded visual (UV) task events--provide clear evidence for both separate and shared resource limitations. Often interference is strongest for T1 and T2 events of the same type, reflecting predominantly different limitations in SA and UV processing. With modest increases in demand, however, interference between different event types can also be made arbitrarily large, reflecting arbitrarily important shared limitations. For even such simple tasks as these, T--T2 interference reflects a combination of relatively local and relatively global sources. PMID:11863322

Arnell, Karen M; Duncan, John

2002-03-01

327

URANIUM PRECIPITATION PROCESS  

DOEpatents

A method for the recovery of uranium from sulfuric acid solutions is described. In the present process, sulfuric acid is added to the uranium bearing solution to bring the pH to between 1 and 1.8, preferably to about 1.4, and aluminum metal is then used as a reducing agent to convert hexavalent uranium to the tetravalent state. As the reaction proceeds, the pH rises amd a selective precipitation of uranium occurs resulting in a high grade precipitate. This process is an improvement over the process using metallic iron, in that metallic aluminum reacts less readily than metallic iron with sulfuric acid, thus avoiding consumption of the reducing agent and a raising of the pH without accomplishing the desired reduction of the hexavalent uranium in the solution. Another disadvantage to the use of iron is that positive ferric ions will precipitate with negative phosphate and arsenate ions at the pH range employed.

Thunaes, A.; Brown, E.A.; Smith, H.W.; Simard, R.

1957-12-01

328

Molecularly imprinted layer-coated silica nanoparticles toward highly selective separation of active diosgenin from Dioscorea nipponica Makino.  

PubMed

This paper reports the molecularly imprinted layer-coated silica nanoparticles toward highly selective separation of active diosgenin (DG) from the crude extracts of Dioscorea nipponica Makino (DNM). It has been demonstrated that DG templates were efficiently imprinted into the silica layer by the use of thermally cleavable urethane bonds between DG and 3-isocyanatopropyltriethoxysilane (IPTS), which was synchronously coated onto the surface of silica mother nanoparticles through a seed-directing surface condensation reaction between DG-IPTS and tetraethoxysilicane (TEOS). After removal of templates by simple thermal cleavage reaction, a high density of recognition sites of DG were created in the silica-coating layer. Afterwards, the DG-imprinted silica nanoparticles were evaluated by rebinding experiments and showed a higher selectivity and affinity to DG than commercial silica. When the imprinted particles were used as solid-phase extraction (SPE) sorbents, the recovery yield of DG was up to 90% by one-step extraction from the hydrolysate of DNM, and the purity of DG was larger than 98% by HPLC analysis. These results reported herein provide the possibility for the highly selective separation and purification of active DG from DNM by the molecular imprinting modification at the surface of common silica adsorbents. PMID:19185307

Zhai, Chunxiao; Lu, Qing; Chen, Xuemei; Peng, Yan; Chen, Lina; Du, Shuhu

2009-01-17

329

Selective extraction and effective separation of galactosylsphingosine (psychosine) and glucosylsphingosine from other glycosphingolipids in pathological tissue samples.  

PubMed

To facilitate the study of the chemical pathology of galactosylsphingosine (psychosine, GalSph) in Krabbe disease and glucosylsphingosine (GlcSph) in Gaucher disease, we have devised a facile method for the effective separation of these two glycosylsphingosines from other glycosphingolipids (GSLs) in Krabbe brain and Gaucher spleen samples. The procedure involves the use of acetone to selectively extract GalSph and GlcSph, respectively, from Krabbe brain and Gaucher spleen samples. Since acetone does not extract other GSLs except modest amounts of galactosylceramide, sulfatide, and glucosylceramide, the positively charged GalSph or GlcSph in the acetone extract can be readily separated from other GSLs by batchwise cation-exchange chromatography using a Waters Accell Plus CM Cartridge. GalSph or GlcSph enriched by this simple procedure can be readily analyzed by thin-layer chromatography or high-performance liquid chromatography. PMID:21136152

Li, Yu-Teh; Li, Su-Chen; Buck, Wayne R; Haskins, Mark E; Wu, Sz-Wei; Khoo, Kay-Hooi; Sidransky, Ellen; Bunnell, Bruce A

2010-12-07

330

Selective inhibition of separated forms of cyclic nucleotide phosphodiesterase from rat heart by some pentasubstituted quercetin analogs.  

PubMed

Synthetic analogs of quercetin were evaluated as inhibitors of cyclic nucleotide phosphodiesterase in rat heart preparations. Three main enzymatic forms of cyclic nucleotide phosphodiesterase can be resolved from rat heart cytosol by isoelectric focusing. Inhibition studies were performed with the whole cytosolic and particulate preparations and with the cytosolic separated enzymatic forms. All the compounds studied proved more potent as inhibitors of the particular preparation than as inhibitors of the cytosolic fraction. With the exception of water-soluble derivatives and quercetin, they showed a better potency to inhibit cyclic AMP than cyclic GMP phosphodiesterase activity of the cytosolic and particulate preparations; likewise, among the three separated enzymatic forms, the cyclic AMP specific form of pI 5.55-6 is the most inhibited by these flavonoid compounds. In all cases, the highest selectivity was observed with pentaethyl quercetin (2). PMID:6291544

Picq, M; Prigent, A F; Nemoz, G; Pacheco, H

1982-09-01

331

Predictive framework for shape-selective separations in three-dimensional zeolites and metal-organic frameworks.  

PubMed

With the growing number of zeolites and metal-organic frameworks (MOFs) available, computational methods are needed to screen databases of structures to identify those most suitable for applications of interest. We have developed novel methods based on mathematical optimization to predict the shape selectivity of zeolites and MOFs in three dimensions by considering the energy costs of transport through possible pathways. Our approach is applied to databases of over 1800 microporous materials including zeolites, MOFs, zeolitic imidazolate frameworks, and hypothetical MOFs. New materials are identified for applications in gas separations (CO2/N2, CO2/CH4, and CO2/H2), air separation (O2/N2), and chemicals (propane/propylene, ethane/ethylene, styrene/ethylbenzene, and xylenes). PMID:23617929

First, Eric L; Gounaris, Chrysanthos E; Floudas, Christodoulos A

2013-04-26

332

Neutron activation determination of noble metals using a selective group separation scheme  

Microsoft Academic Search

A rapid and comprehensive method has been developed for the determination of ppm to sub-ppb amounts of Ru, Pd, Ag, Os, Ir,\\u000a Pt and Au, based on thermal neutron irradiation, dissolution of samples, selective absorption on Srafion NMRR ion exchange\\u000a resin and high resolution ?-ray spectrometry. Two noble metals “specific” resins were tested for their absorption behaviour.\\u000a The method has

R. A. Nadkarni; G. H. Morrison

1977-01-01

333

The design of microporous graphitic adsorbents for selective separation of gases  

Microsoft Academic Search

We discuss the design of optimum graphitic microstructures for selective adsorption from gaseous mixtures. Binary mixtures of methane and nitrogen at 293.1 K and pressures up to 1 bar were chosen as model systems. Non-local density functional theory (DFT) was used to predict the adsorption of nitrogen and methane in slit-shaped pores for a pore size range of 0.5–5 nm.

P Kluson; S Scaife; N Quirke

2000-01-01

334

Thin layer molecularly imprinted composite membranes for selective separation of erythromycin from water  

Microsoft Academic Search

Molecularly imprinted composite membranes for selective binding of erythromycin were synthesized by UV initiated photo-copolymerization\\u000a using polysulfone ultrafiltration (PSF) membranes as porous supports. The thin imprinted layers deposited on the surface of\\u000a the support membranes were formed by copolymerization of acrylic acid (AA) as functional monomer and ethylene glycol dimethacrylate\\u000a (EGDMA) as cross-linker in the presence of erythromycin as template

Jinyang Yu; Xiaoling Hu; Dapeng Li; Cuicui Jiao

2009-01-01

335

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

336

Practical solvent system selection for counter-current separation of pharmaceutical compounds.  

PubMed

Counter-current chromatography (CCC) is a technique that shows a lot of potential for large scale purification. Its usefulness in a "research and development" pharmaceutical environment has been investigated, and the conclusions are shown in this article. The use of CCC requires the development of an appropriate solvent system (a parameter of critical importance), a process which can be tedious. This article presents a novel strategy, combining a statistical approach and fast HPLC to generate a three-dimensional partition coefficient map and rapidly predict an optimal solvent system. This screen is performed in half a day and involves 9 experiments per solvent mixture. Test separations were performed using that screen to ensure the validity of the method. PMID:18801491

Dubant, Stéphane; Mathews, Ben; Higginson, Paul; Crook, Robert; Snowden, Martin; Mitchell, John

2008-09-05

337

Radiostrontium separation and measurement in a single step using plastic scintillators plus selective extractants. Application to aqueous sample analysis.  

PubMed

This study describes a new protocol for (90)Sr determination in water samples based on the use of a selective extractant (DtBuCH18C6) and plastic scintillator microspheres. The proposed procedure unifies chemical separation and sample measurement preparation in a single step to reduce the effort, time and reagents required for analysis. In addition, the final measurement does not produce mixed waste. The minimum activity detectable for 10 mL of sample solution is 0.46 Bq L(-1). Relative errors for the determination of (90)Sr activity in drinking, sea and river waters are less than 4%. PMID:21237307

Bagán, H; Tarancón, A; Rauret, G; García, J F

2010-12-01

338

SULFIDE METHOD PLUTONIUM SEPARATION  

DOEpatents

A process is described for the recovery of plutonium from neutron irradiated uranium solutions. Such a solution is first treated with a soluble sullide, causing precipitation of the plutoniunn and uraniunn values present, along with those impurities which form insoluble sulfides. The precipitate is then treated with a solution of carbonate ions, which will dissolve the uranium and plutonium present while the fission product sulfides remain unaffected. After separation from the residue, this solution may then be treated by any of the usual methods, such as formation of a lanthanum fluoride precipitate, to effect separation of plutoniunn from uranium.

Duffield, R.B.

1958-08-12

339

Separation of alcohol-water mixtures by selective adsorption. Semi-annual technical progress report  

SciTech Connect

The intent is to chemically modify polyvinyl chloride so as to convert it to a material capable of selectively adsorbing ethyl alcohol from alcohol-water mixtures. This concept differs from the more conventional technique in which water is absorbed from the mixture by, for example, molecular sieves. The approach is to attempt to remove alcohol from mixtures containing a low percentage of alcohol. Such a solution might originate directly from the fermentation process and contain approximately 10% alcohol, or it might consist of distillation residues containing low alcohol concentrations that are uneconomical to handle by further distillation.

Dearborn, R.J.

1982-03-23

340

Fluoridized iron phosphate as a novel adsorbent for selective separation/isolation of cytochrome c.  

PubMed

Fluoridized iron phosphate (F-FePO) is prepared via a hydrothermal protocol and characterized by means of (57)Fe Mössbauer spectra, Fourier transform infrared, and surface charge analysis. For the first time, F-FePO is used as an adsorbent for the adsorption of proteins, which exhibits favorable selectivity toward cytochrome c (cyt-c) in the presence of acidic and neutral proteins under controlled experimental conditions. At pH 10.5, an adsorption efficiency of 100% is achieved for 60 mg L(-1) cyt-c in 1.0 mL of sample solution using 6.0 mg F-FePO. The adsorption behavior is consistent with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 37.59 ?g mg(-1). The retained cyt-c on F-FePO could be readily collected by 0.1 mol L(-1) Na(2)CO(3)-NaHCO(3) buffer (pH 10.5), deriving a recovery of 100%. Circular dichroism spectra indicate no conformational change for cyt-c after the adsorption and desorption processes, demonstrating the favorable biocompatibility of the fluoridized iron phosphate. F-FePO is employed for the selective isolation of cyt-c from a spiked human whole blood, achieving satisfactory results by assay with SDS-polyacrylamide gel electrophoresis and native polyacrylamide gel electrophoresis. PMID:21983982

Tang, Shisong; Wang, WenJing; Chen, XuWei; Wang, JianHua

2011-10-08

341

Selective separation of flavonoid glycosides in Dalbergia odorifera by matrix solid-phase dispersion using titania.  

PubMed

Dalbergia odorifera contains high concentrations of flavonoid aglycones and trace flavonoid glycosides. In this study, trace flavonoid glycosides were separated from D. odorifera by titania with matrix solid-phase dispersion (MSPD). Before the MSPD experiment, four standards, including two isoflavone glycosides (genistin and formononetin-8-C-apiosyl (1-6)-glucoside) and their aglycones (genistein and formononetin), were used to compare their retention on a titania column. The effect of acetonitrile concentration and pH on their retention was investigated and a conclusion was drawn that high acetonitrile concentration and pH lead to the greatest difference in the retention of flavonoid as glycosides and aglycones. Besides hydrophilic interaction and ligand-exchange interaction may exist between sugar moiety of flavonoid glycoside and titania, so that flavonoid glycosides have stronger retention than that of aglycones. Based on the chromatographic rule of flavonoid as glycosides and aglycones on the titania column, the MSPD method was optimized to elute high concentration flavonoid aglycones first with 90% acetonitrile and 10% water containing 100 mM ammonium acetate buffer, and then to elute trace flavonoid glycosides with 20% acetonitrile and 80% water containing 1% trifluoroacetate (TFA). Isolated flavonoid glycosides were further analyzed by UPLC-MS/MS, and their fragmentation in MS(2) showed they are C-glycosyl flavonoids. PMID:21491599

Xu, Lingyan; Shi, Hui; Liang, Tu; Feng, Jiatao; Jin, Yu; Ke, Yanxiong; Liang, Xinmiao

2011-04-13

342

Objective source selection in Blind Source Separation of AEPs in children with Cochlear Implants.  

PubMed

Multi-channel Auditory Evoked Potentials (AEPs) are a useful methodology for evaluating the auditory performance of children with Cochlear Implants (CIs). These recordings are generally contaminated, not only with well known physiological artifacts (blinking, muscle) and line noise etc., but also by CI artifact. The CI induces an artifact in the recording at the electrodes in the temporal lobe area (where it is implanted) when specific tones are presented, this artifact in particular makes the detection and analysis of AEPs much more challenging. This paper evaluates the convenience of using Blind Source Separation (BSS) and Independent Component Analysis (ICA) in order to identify the AEPs from ongoing recordings and to isolate the artifact when testing a child with a CI. We propose a new procedure to elicit an objective differentiation between the independent components (ICs) related to the AEPs and CI artifact; two concepts are fundamental in this procedure Mutual Information (MI) and Clustering. Finally, the variability of three BSS/ICA algorithms is assessed; in order to determine which one is more convenient to isolate the respective ICs of interest. Temporal decorrelation based ICA showed the least change in the estimation of both the AEPs and the CI artifact; this has allowed for considerable autonomy in the construction of relevant, consistent clusters. PMID:18003443

Castañeda-Villa, N; James, C J

2007-01-01

343

PROCESS OF RECOVERING URANIUM  

DOEpatents

A method is presented for separating and recovering uranium from a complex mixure of impurities. The uranium is dissolved to produce an aqueous acidic solution including various impurities. In accordance with one method, with the uranium in the uranyl state, hydrogen cyanide is introduced into the solution to complex the impurities. Subsequently, ammonia is added to the solution to precipitate the uraniunn as ammonium diuranate away from the impurities in the solution. Alternatively, the uranium is precipitated by adding an alkaline metal hydroxide. In accordance with the second method, the uranium is reduced to the uranous state in the solution. The reduced solution is then treated with solid alkali metal cyanide sufficient to render the solution about 0.1 to 1.0 N in cyanide ions whereat cyanide complex ions of the metal impurities are produced and the uranium is simultaneously precipituted as uranous hydroxide. Alternatively, hydrogen cyanide may be added to the reduced solution and the uranium precipitated subsequently by adding ammonium hydroxide or an alkali metal hydroxide. Other refinements of the method are also disclosed.

Kilner, S.B.

1959-12-29

344

Isotope separation by laser means  

DOEpatents

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

1982-06-15

345

Distributed Physical and Molecular Separations for Selective Harvest of Higher Value Wheat Straw Components Project  

SciTech Connect

Wheat straw (Triticum aestivum L.) is an abundant source of plant fiber. It is regenerated, in large quantities, every year. At present, this potentially valuable resource is greatly under-exploited. Most of the excess straw biomass (i.e., tonnage above that required for agronomic cropping system sustainability) is managed through expensive chopping/tillage operations and/or burnt in the field following harvest, resulting in air pollution and associated health problems. Potential applications for wheat straw investigated within this project include energy and composites manufacture. Other methods of straw utilization that will potentially benefit from the findings of this research project include housing and building, pulp and paper, thermal insulation, fuels, and chemicals. This project focused on components of the feedstock assembly system for supplying a higher value small grains straw residue for (1) gasification/combustion and (2) straw-thermoplastic composites. This project was an integrated effort to solve the technological, infrastructural, and economic challenges associated with using straw residue for these bioenergy and bioproducts applications. The objective of the research is to contribute to the development of a low-capital distributed harvesting and engineered storage system for upgrading wheat straw to more desirable feedstocks for combustion and for straw-plastic composites. We investigated two processes for upgrading wheat straw to a more desirable feedstock: (1) An efficient combine-based threshing system for separating the internodal stems from the leaves, sheaths, nodes, and chaff. (2) An inexpensive biological process using white-rot fungi to improve the composition of the mechanically processed straw stems.

Hess, J.R

2005-01-31

346

Distributed Physical and Molecular Separations for Selective Harvest of Higher Value Wheat Straw Components Project  

SciTech Connect

Wheat straw (Triticum aestivum L.) is an abundant source of plant fiber. It is regenerated, in large quantities, every year. At present, this potentially valuable resource is greatly under-exploited. Most of the excess straw biomass (i.e., tonnage above that required for agronomic cropping system sustainability) is managed through expensive chopping/tillage operations and/or burnt in the field following harvest, resulting in air pollution and associated health problems. Potential applications for wheat straw investigated within this project include energy and composites manufacture. Other methods of straw utilization that will potentially benefit from the findings of this research project include housing and building, pulp and paper, thermal insulation, fuels, and chemicals. This project focused on components of the feedstock assembly system for supplying a higher value small grains straw residue for (1) gasification/combustion and (2) straw-thermoplastic composites. This project was an integrated effort to solve the technological, infrastructural, and economic challenges associated with using straw residue for these bioenergy and bioproducts applications. The objective of the research is to contribute to the development of a low-capital distributed harvesting and engineered storage system for upgrading wheat straw to more desirable feedstocks for combustion and for straw-plastic composites. They investigated two processes for upgrading wheat straw to a more desirable feedstock: (1) an efficient combine-based threshing system for separating the intermodal stems from the leaves, sheaths, nodes, and chaff. (2) An inexpensive biological process using white-rot fungi to improve the composition of the mechanically processed straw stems.

N /A

2004-09-30

347

Separation of alcohol-water mixtures by selective adsorption. Final technical report  

SciTech Connect

The plastic waste that is generated during the manufacture of electric storage batteries has been utilized in the preparation of new and different resins. This waste is pure polyvinyl chloride and in storage batteries sintered sheets of the poly;mer are used as cell separators. The scrap, in the form of thin flakes, can be ground to any particle size range including powder. If the particles are about 30 to 60 mesh they are granular and physically resemble the resins used in adsorption and ion exchange processes. A procedure was developed for the replacement of a portion of the chlorine atoms in the granular polyvinyl chloride with amine nitrogen-containing groups. Reaction conditions were investigated and it was established that low temperatures (80 to 95/sup 0/C) and rather long reaction times (24 to 72 hours) resulted in minimal degradation of the polyvinyl chloride and replacement of up to one-third of the chlorine atoms with amine groups. In most instances the modified PVC resins contained four to six percent nitrogen. A number of preparations were tested for ethyl alcohol adsorption by suspending one part of the resin in about four parts by weight of dilute (usually ten percent) alcohol and determining the alcohol concentration following filtration of the suspension. The decrease in alcohol content generally amounted to from 0.6 to 1.1 percent, indicating that alcohol adsorption to the extent of 25 to 50 mg. per gram of resin had occurred. Adsorption tests in which dilute alcohol was passed through about 300 g. of modified resin contained in a 4 x 50 cm. chromatographic column were also conducted.

Dearborn, R.J.

1982-12-24

348

SOLVENT EXTRACTION PROCESS FOR URANIUM RECOVERY  

DOEpatents

A process is described for extracting uranium from uranium ore, wherein the uranium is substantially free from molybdenum contamination. In a solvent extraction process for recovering uranium, uranium and molybdenum ions are extracted from the ore with ether under high acidity conditions. The ether phase is then stripped with water at a lower controiled acidity, resaturated with salting materials such as sodium nitrate, and reextracted with the separation of the molybdenum from the uranium without interference from other metals that have been previously extracted.

Clark, H.M.; Duffey, D.

1958-06-17

349

Exploring reverse shape selectivity and molecular sieving effect of metal-organic framework UIO-66 coated capillary column for gas chromatographic separation.  

PubMed

Metal-organic frameworks (MOFs) which offer a variety of topologies, porous networks and high surface areas are promising and have potential for the applications of specific adsorption, isomerization, catalysis and separation. UIO-66 is the first MOF that has been observed to have reverse shape selectivity. However, such reverse shape selectivity of MOFs has never been explored for capillary gas chromatographic separation. Here we report the fabrication of MOF UIO-66 coated capillary column and exploration of the reverse shape selectivity and molecular sieving effect of such column for capillary gas chromatographic separation of alkane isomers and benzene homologues with excellent selectivity and precision. The adsorption enthalpies and entropies on the interaction between hydrocarbons and UIO-66 were measured to illustrate the energy effect on the separation of alkane isomers and benzene homologues on the UIO-66 coated capillary column. UIO-66 coated capillary column gave preferential retention of branched alkane isomers over their linear isomer, showing reverse shape selectivity, making UIO-66 coated capillary column attractive for capillary gas chromatographic separation of alkane isomers. iso-Propylbenzene (branched) eluted after n-propylbenzene on the UIO-66 coated capillary column again shows reverse shape selectivity. However, much bulkier 1,3,5-trimethylbenzene eluted earlier than n-propylbenzene and iso-propylbenzene on the UIO-66 coated capillary column, exhibiting molecular sieving effect. The combination of reverse shape selectivity with molecular sieving effect makes the UIO-66 coated capillary column promising for the separation of structural isomers. PMID:22920300

Chang, Na; Yan, Xiu-Ping

2012-08-10

350

300 Area Uranium Stabilization Through Polyphosphate Injection: Final Report  

SciTech Connect

The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. This report summarizes the work on the polyphosphate injection project, including bench-scale laboratory studies, a field injection test, and the subsequent analysis and interpretation of the results. Previous laboratory tests have demonstrated that when a soluble form of polyphosphate is injected into uranium-bearing saturated porous media, immobilization of uranium occurs due to formation of an insoluble uranyl phosphate, autunite [Ca(UO2)2(PO4)2•nH2O]. These tests were conducted at conditions expected for the aquifer and used Hanford soils and groundwater containing very low concentrations of uranium (10-6 M). Because autunite sequesters uranium in the oxidized form U(VI) rather than forcing reduction to U(IV), the possibility of re-oxidation and subsequent re-mobilization is negated. Extensive testing demonstrated the very low solubility and slow dissolution kinetics of autunite. In addition to autunite, excess phosphorous may result in apatite mineral formation, which provides a long-term source of treatment capacity. Phosphate arrival response data indicate that, under site conditions, the polyphosphate amendment could be effectively distributed over a relatively large lateral extent, with wells located at a radial distance of 23 m (75 ft) reaching from between 40% and 60% of the injection concentration. Given these phosphate transport characteristics, direct treatment of uranium through the formation of uranyl-phosphate mineral phases (i.e., autunite) could likely be effectively implemented at full field scale. However, formation of calcium-phosphate mineral phases using the selected three-phase approach was problematic. Although amendment arrival response data indicate some degree of overlap between the reactive species and thus potential for the formation of calcium-phosphate mineral phases (i.e., apatite formation), the efficiency of this treatment approach was relatively poor. In general, uranium performance monitoring results support the hypothesis that limited long-term treatment capacity (i.e., apatite formation) was established during the injection test. Two separate overarching issues affect the efficacy of apatite remediation for uranium sequestration within the 300 Area: 1) the efficacy of apatite for sequestering uranium under the present geochemical and hydrodynamic conditions, and 2) the formation and emplacement of apatite via polyphosphate technology. In addition, the long-term stability of uranium sequestered via apatite is dependent on the chemical speciation of uranium, surface speciation of apatite, and the mechanism of retention, which is highly susceptible to dynamic geochemical conditions. It was expected that uranium sequestration in the presence of hydroxyapatite would occur by sorption and/or surface complexation until all surface sites have been depleted, but that the high carbonate concentrations in the 300 Area would act to inhibit the transformation of sorbed uranium to chernikovite and/or autunite. Adsorption of uranium by apatite was never considered a viable approach for in situ uranium sequestration in and of itself, because by definition, this is a reversible reaction. The efficacy of uranium sequestration by apatite assumes that the adsorbed uranium would subsequently convert to autunite, or other stable uranium phases. Because this appears to not be the case in the 300 Area aquifer, even in locations near the river, apatite may have limited efficacy for the retention and long-term immobilization of uranium at the 300 Area site..

Vermeul, Vincent R.; Bjornstad, Bruce N.; Fritz, Brad G.; Fruchter, Jonathan S.; Mackley, Rob D.; Newcomer, Darrell R.; Mendoza, Donaldo P.; Rockhold, Mark L.; Wellman, Dawn M.; Williams, Mark D.

2009-06-30

351

DISSOLUTION OF URANIUM FUELS BY MONOOR DIFLUOROPHOSPHORIC ACID  

DOEpatents

A method of dissolving and separating uranium from a uranium matrix fuel element by dissolving the uraniumcontaining matrix in monofluorophosphoric acid and/or difluorophosphoric acid at temperatures ranging from 150 to 275 un. Concent 85% C, thereafter neutralizing the solution to precipitate uranium solids, and converting the solids to uranium hexafluoride by treatment with a halogen trifluoride is presented. (AEC)

Johnson, R.; Horn, F.L.; Strickland, G.

1963-05-01

352

Using a Buffer Gas Modifier to Change Separation Selectivity in Ion Mobility Spectrometry.  

PubMed

The mobilities of a set of common ?-amino acids, four tetraalkylammonium ions, 2,4-dimethyl pyridine (2,4-lutidine), 2,6-di-tert-butyl pyridine (DTBP), and valinol were determined using electrospray ionization-ion mobility spectrometry-quadrupole mass spectrometry (ESI-IMS-QMS) while introducing 2-butanol into the buffer gas. The mobilities of the test compounds decreased by varying extents with 2-butanol concentration in the mobility spectrometer. When the concentration of 2-butanol increased from 0.0 to 6.8 mmol m(-3) (2.5×10(2) ppmv), percentage reductions in mobilities were: 13.6% (serine), 12.2% (threonine), 10.4% (methionine), 10.3% (tyrosine), 9.8% (valinol), 9.2% (phenylalanine), 7.8% (tryptophan), 5.6% (2,4-lutidine), 2.2% (DTBP), 1.0% (tetramethylammonium ion, TMA, and tetraethylammonium ion, TEA), 0.0% (tetrapropylammonium ion, TPA), and 0.3% (tetrabutylammonium ion, TBA). These variations in mobility depended on the size and steric hindrance on the charge of the ions, and were due to formation of large ion-2-butanol clusters. This selective variation in mobilities was applied to the resolution of a mixture of compounds with similar reduced mobilities such as serine and valinol, which overlapped in N(2)-only buffer gas in the IMS spectrum. The relative insensitivity of tetraalkylammonium ions and DTBP to the introduction of 2-butanol into the buffer gas was explained by steric hindrance of the four alkyl substituents in tetraalkylammonium ions and the two tert-butyl groups in DTBP, which shielded the positive charge of the ion from the attachment of 2-butanol molecules. Low buffer gas temperatures (100 °C) produced the largest reductions in mobilities by increasing ion-2-butanol interactions and formation of clusters; high temperatures (250 °C) prevented the formation of clusters, and no reduction in ion mobility was obtained with the introduction of 2-butanol into the buffer gas. Low temperatures and high concentrations of 2-butanol produced a series of ion clusters with one to three 2-butanol molecules in compounds without steric hindrance. Clusters of two and three molecules of 2-butanol were also visible. Ligand-saturation on the positive ions with 2-butanol molecules occurred at high concentrations of modifier (6.8 mmol m(-3) at 150°C); when saturated, no further reduction in mobility occurred when 2-butanol was introduced into the buffer gas. PMID:21344065

Fernández-Maestre, Roberto; Wu, Ching; Hill, Herbert H

2010-12-01

353

METHOD OF SEPARATING PLUTONIUM  

DOEpatents

Plutonium hexafluoride is a satisfactory fluorinating agent and may be reacted with various materials capable of forming fluorides, such as copper, iron, zinc, etc., with consequent formation of the metal fluoride and reduction of the plutonium to the form of a lower fluoride. In accordance with the present invention, it has been found that the reactivity of plutonium hexafluoride with other fluoridizable materials is so great that the process may be used as a method of separating plutonium from mixures containing plutonium hexafluoride and other vaporized fluorides even though the plutonium is present in but minute quantities. This process may be carried out by treating a mixture of fluoride vapors comprising plutonium hexafluoride and fluoride of uranium to selectively reduce the plutonium hexafluoride and convert it to a less volatile fluoride, and then recovering said less volatile fluoride from the vapor by condensation.

Brown, H.S.; Hill, O.F.

1958-02-01

354

Functionalized flexible MOFs as fillers in mixed matrix membranes for highly selective separation of CO2 from CH4 at elevated pressures.  

PubMed

Mixed matrix membranes (MMMs) composed of a glassy polymer (polysulfone) and the flexible metal organic framework NH(2)-MIL-53(Al) exhibit excellent separation properties. In contrast to most reported membranes, CO(2)/CH(4) separation selectivity increases with pressure, related to the flexibility of the filler. PMID:21769350

Zornoza, Beatriz; Martinez-Joaristi, Alberto; Serra-Crespo, Pablo; Tellez, Carlos; Coronas, Joaquin; Gascon, Jorge; Kapteijn, Freek

2011-07-18

355

Preconcentration determination of inorganic anions and organic acids in power plant waters separation optimization through control of column capacity and selectivity  

Microsoft Academic Search

An anion-exchange column has been developed for the separation of anions inpower plant waters. The column has been optimized, in terms of capacity and selectivity, to allow the isocratic separation of weakly retained organic and inorganic anions, in addition to more strongly retained anions. This new moderate capacity anion-exchange column was utilised for the preconcentration ion chromatography (IC) determination of

Mahmood Toofan; John R. Stillian; Christopher A. Pohl; Peter E. Jackson

1997-01-01

356

Soil decontamination using aqueous biphasic separation  

SciTech Connect

This paper summarizes efforts to develop a biphasic extraction process for separating ultrafine particulate contaminants from soils having high amounts of silt and clay. This work has thus far dealt with the removal of refractory uranium particles from the soils at Fernald, Ohio. The separation process involves the selective partitioning of ultra-fine particles between two immiscible aqueous phases. The authors have conducted batch extraction studies and are now beginning to scaleup the process for pilot-plant testing at Argonne National Laboratory (ANL). The results of these extraction studies are discussed.

Chaiko, D.J.; Mensah-Biney, R.; Gupta, D.

1994-02-01

357

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

358

ABSORPTIOMETRIC DETERMINATION OF IRON IN URANIUM AND ITS COMPOUNDS. URANIUM METAL, AMMONIUM DIURANATE AND URANOUS FLUORIDE (AFTER REMOVAL OF FLUORINE)  

Microsoft Academic Search

The possibility of determining microgram quantities of iron in uranium ; solutions using thioglycolic acid and ammonia without a prior separation from ; uranium has been studied and a method proposed. Citrate and carbonate ions are ; employed to prevent precipitation of uranium and destroy the color due to uranium ; and thioglycolic acid, respectively. Solutions containing uranyl ions do

A. B. Crowther; F. Warburton; R. Dickenson; S. M. Dykes

1950-01-01

359

Ages of major uranium mineralization and lead loss in the Key Lake uranium deposit, northern Saskatchewan, Canada  

Microsoft Academic Search

Uranium and lead isotope ratios were measured on nine ore samples and four mineral separates from the Deilmann orebody of the Key Lake uranium-nickel deposit. The time of primary mineralization is the oldest reported for Proterozoic unconformityrelated uranium deposits in the Athabasca basin. Data obtained in this study show that lead loss (or uranium gain) has occurred in highgrade rocks

L. K. Trucki; J. C. Banar; D. B. Curtis; A. J. Gancarz

1984-01-01

360

Wide angle, single screen, gridded square-loop frequency selective surface for diplexing two closely separated frequency bands  

NASA Astrophysics Data System (ADS)

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 incident angle from n degrees normal to 40 degrees from normal.

Wu, Te-Kao

1993-07-01

361

Selective population of the [1s2s] {sup 1}S{sub 0} and [1s2s] {sup 3}S{sub 1} states of He-like uranium  

SciTech Connect

The formation of the [1s2s] S states in heliumlike uranium (U{sup 90+}) has been studied in relativistic collisions of initially lithiumlike uranium (U{sup 89+}) ions with N{sub 2} target molecules. By measuring projectile x-ray emission in coincidence with projectile ionization, a strong selectivity for the formation of the [1s2s] S states in heliumlike uranium is observed. This selectivity is found to be unaffected by the subsequent rearrangement of the atomic orbitals involved. By measuring the photon emission associated with the decay of the [1s2s] {sup 1}S{sub 0} and the [1s2s] {sup 3}S{sub 1} substates, we obtain for their relative population probabilities a ratio of close to 1. This finding deviates considerably from the assumption of a statistical distribution 2J+1.

Rzadkiewicz, J. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); The Soltan Institute for Nuclear Studies, 05-400 Swierk (Poland); Stoehlker, Th.; Gumberidze, A.; Reuschl, R.; Spillmann, U.; Tashenov, S.; Trotsenko, S. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Institut fuer Kernphysik, Universitaet Frankfurt (Germany); Banas, D. [Institute of Physics, Swietokrzyska Academy, Kielce (Poland); Beyer, H. F.; Bosch, F.; Brandau, C.; Ionescu, D. C.; Kozhuharov, C.; Nandi, T. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Dong, C. Z. [Department of Physics, Northwest Normal University, Lanzhou (China); Fritzsche, S.; Surzhykov, A. [Universitaet Kassel (Germany); Gojska, A. [Soltan Institute for Nuclear Studies, Swierk (Poland); Hagmann, S. [Institut fuer Kernphysik, Universitaet Frankfurt (Germany); Sierpowski, D. [Institute of Physics, Jagiellonian University, Cracow (Poland)] (and others)

2006-07-15

362

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

363

Binary ionic liquid mixtures as gas chromatography stationary phases for improving the separation selectivity of alcohols and aromatic compounds.  

PubMed

Binary mixtures of two ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride (BMIM-Cl) and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (BMIM-NTf2), have been studied for the first time as gas chromatographic stationary phases. The two ILs differ only in the nature of the associated anion. The solvation parameter model was used to examine the change of solvation interactions with the IL stationary phase composition. The hydrogen bond basicity increased linearly as the stationary phase was enriched with the BMIM-Cl IL. The retention factor of short-chained alcohols increased by as much as 1100% when performing the separation on a column containing an IL mixture of 25% BMIM-NTf2/75% BMIM-Cl compared to that of the neat BMIM-NTf2 IL column. By tuning the composition of the IL-stationary phase, the separation selectivity and resolution factors of alcohols and aromatic compounds were improved. A reversal of elution order was observed for specific classes of analytes with enhancements in the stationary phase hydrogen bond basicity. PMID:18207157

Baltazar, Quinner Q; Leininger, Suzette K; Anderson, Jared L

2008-01-06

364

Oxidation states of uranium in depleted uranium particles from Kuwait  

Microsoft Academic Search

The oxidation states of uranium in depleted uranium (DU) particles were determined by synchrotron radiation based ?-XANES, applied to individual particles isolated from selected samples collected at different sites in Kuwait. Based on scanning electron microscopy with X-ray microanalysis prior to ?-XANES, DU particles ranging from submicrons to several hundred micrometers were observed. The median particle size depended on sources

B. Salbu; K. Janssens; O. C. Lind; K. Proost; L. Gijsels; P. R. Danesi

2004-01-01

365

ELECTROCHEMICAL DECONTAMINATION AND RECOVERY OF URANIUM VALUES  

DOEpatents

An electrochemical process is described for separating uranium from fission products. The method comprises subjecting the mass of uranium to anodic dissolution in an electrolytic cell containing aqueous alkali bicarbonate solution as its electrolyte, thereby promoting a settling from the solution of a solid sludge from about the electrodes and separating the resulting electrolyte solution containing the anodically dissolved uranium from the sludge which contains the rare earth fission products.

McLaren, J.A.; Goode, J.H.

1958-05-13

366

Chemical Properties of Uranium Hexafluoride, UF6  

Microsoft Academic Search

Uranium hexafluoride has the distinction of being the only stable gaseous compound of uranium known up to the present moment. Because of this property it is the only compound that can be used for processes of isotope separation, such as diffusion, thermal diffusion, centrifuge separation, distillation, and other of a similar nature. Here is a short description of the properties

Grosse; Aristid V

1941-01-01

367

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

368

Multifunctional inorganic-organic hybrid nanospheres for rapid and selective luminescence detection of TNT in mixed nitroaromatics via magnetic separation.  

PubMed

Rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT) in aqueous solution differentiating from other nitroaromatics and independent of complicated instruments is in high demand for public safety and environmental monitoring. Despite of many methods for TNT detection, it is hard to differentiate TNT from 2,4,6-trinitrophenol (TNP) due to their highly similar structures and properties. In this work, via a simple and versatile method, LaF3?Ce(3+)-Tb(3+)and Fe3O4 nanoparticle-codoped multifunctional nanospheres were prepared through self-assembly of the building blocks. The luminescence of these nanocomposites was dramatically quenched via adding nitroaromatics into the aqueous solution. After the magnetic separation, however, the interference of other nitroaromatics including 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (DNT), and nitrobenzene (NB) was effectively overcome due to the removal of these coexisting nitroaromatics from the surface of nanocomposites. Due to the formation of TNT(-)-RCONH3(+), the TNT was attached to the surface of the nanocomposites and was quantitatively detected by the postexposure luminescence quenching. Meanwhile, the luminescence intensity is negatively proportional to the concentration of TNT in the range of 0.01-5.0?g/mL with the 3? limit of detection (LOD) of 10.2ng/mL. Therefore, the as-developed method provides a novel strategy for rapid and selective detection of TNT in the mixture solution of nitroaromatics by postexposure luminescence quenching. PMID:24148441

Ma, Yingxin; Huang, Sheng; Wang, Leyu

2013-07-20

369

THORIUM, URANIUM AND POTASSIUM IN SOME SANDSTONES  

Microsoft Academic Search

Thorinm, uranium, and potassium concentrations have been determined in ; nineteen sands and sandstones by gamma -ray spectrometry, fluorometric uranium ; analysis, and alpha counting. The samples were selected so that both common ; and extreme thorium and uranium ratios would be represented. The average and ; nearly uniform values found in orthoquartzitic, clay-free sands were potassium ; (as metal)

E. G. Murray; J. A. S. Adams

1958-01-01

370

Thorium, uranium and potassium in some sandstones  

Microsoft Academic Search

Thorium, uranium, and potassium concentrations have been determined in nineteen sands and sandstones by -ray spectrometry, fluorometric uranium analysis, and -counting. The samples were selected so that both common and extreme thorium and uranium ratios would be represented. The average and nearly uniform values found in orthoquartzitic, clay-free sands were potassium (as metal) 0.64 ± 0.04 per cent ; thorium

Elaine G. Murray; John A. S. Adams

1958-01-01

371

Evolution of ultra-thin dense-selective layer from single-layer to dual-layer hollow fibers using novel Extem ® polyetherimide for gas separation  

Microsoft Academic Search

The aims of this study are to fabricate Extem® hollow fibers with an ultra-thin dense-selective layer for gas separation and to use this brand new amorphous thermoplastic polyetherimide (PEI) as a model material to reveal the fundamentals of hollow fiber membrane fabrication. The evolution of membrane morphology, final dense-selective layer thickness and O2\\/N2 selectivity from single-layer to dual-layer spinning have

Na Peng; Tai-Shung Chung; Mei Lin Chng; Weiqiang Aw

2010-01-01

372

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

373

PROCESS OF RECOVERING URANIUM  

DOEpatents

An improved precipitation method is described for the recovery of uranium from aqueous solutions. After removal of all but small amounts of Ni or Cu, and after complexing any iron present, the uranium is separated as the peroxide by adding H/sub 2/O/sub 2/. The improvement lies in the fact that the addition of H/sub 2/O/sub 2/ and consequent precipitation are carried out at a temperature below the freezing; point of the solution, so that minute crystals of solvent are present as seed crystals for the precipitation.

Price, T.D.; Jeung, N.M.

1958-06-17

374

Determination of molybdenum and uranium in biological materials by radiochemical neutron activation analysis  

Microsoft Academic Search

Recently developed radiochemical separation scheme for the simultaneous detemination of trace amounts of molybdenum and uranium in biological materials by NAA has been further refined and used for the detemination of these elements in several certified reference materials. The method assures very selective and quantitative separation of the indicator radionuclides:99Mo-99mTc and239Np from practically all accompanying activities followed by almost interference-free

B. Danko; R. Dybczyfiski

1997-01-01

375

Thin-layer chromatographic separation of zirconium, hafnium, thorium, uranium, and the rare earths on DEAE-cellulose in sulfate media  

Microsoft Academic Search

The thin-layer chromatographic behavior on DEAE-cellulose in gated in ; detail for Hf(IV), Zr(iV), U(VI), Th(IV) and the trivalent rare earths and the ; work is described in this paper. Procedures were developed for the separation of ; Zr(IV) and Hf(IV), and for the two-dimensional separation of Zr(IV), Hf(IV), ; Th(IV), U(VI) and the trivalent rare earths. (JSR);

T. Shimizu; A. Muto

1974-01-01

376

Effect of Pre?Filtration on Selective Isolation of Tat Protein by Affinity Membrane Separation: Analysis of Flux, Separation Efficiency, and Processing Time  

Microsoft Academic Search

The isolation and purification of Tat protein from bacterial lysate using avidin?biotin interaction in microfiltration membranes have been reported in the literature. To increase the efficacy of the technique, improvements in flux, Tat separation efficiency, and processing time are essential. In the current research work a pre?filtration step was introduced to remove unwanted high molecular weight proteins and other impurities

Saurav Datta; D. Bhattacharyya; P. D. Ray; A. Nath; M. Toborek

2007-01-01

377

METHOD OF PRODUCING URANIUM  

DOEpatents

A modified process is described for the production of uranium metal by means of a bomb reduction of UF/sub 4/. Difficulty is sometimes experienced in obtaining complete separation of the uranium from the slag when the process is carried out on a snnall scale, i.e., for the production of 10 grams of U or less. Complete separation may be obtained by incorporating in the reaction mixture a quantity of MnCl/sub 2/, so that this compound is reduced along with the UF/sub 4/ . As a result a U--Mn alloy is formed which has a melting point lower than that of pure U, and consequently the metal remains molten for a longer period allowing more complete separation from the slag.

Foster, L.S.; Magel, T.T.

1958-05-13

378

Mechanistic investigation of solvent extraction based on anion-functionalized ionic liquids for selective separation of rare-earth ions.  

PubMed

In this study, solvation has been found to be a dominant mechanism in an ionic liquid (IL)-based extraction system for rare earth elements (REEs). Trioctylmethylammonium di(2-ethylhexyl)phosphate ([TOMA][DEHP]), an anion-functionalized IL extractant, was used in 1-alkyl-3-methylimidizolium bis[(trifluoromethylsulfonyl)]imide ([C(n)mim][NTf2], n = 4, 6, 8, 10) and 1-alkyl-3-methylimidizolium bis(perfluoroethanesulfonyl)imide ([C(n)mim][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 IL cation increased from butyl (C4) to decyl (C10). This behavior is in sharp contrast to that exhibited by the conventional molecular extractants, whose extraction efficiencies are strongly dependent on the hydrophobicity of IL cations. Furthermore, the addition of IL cations ([C(n)mim](+)) in [C(n)mim]Cl form or IL anions ([NTf2](-) or [BETI](-)) in Li[NTf2] or Li[BETI] form to the aqueous phase had a minor 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 a conventional organic solvent, diisopropylbenzene (DIPB). This study highlights the potential of developing a comprehensive IL-based extraction strategy for REEs separations via ionic extractants. PMID:23595558

Sun, Xiaoqi; Luo, Huimin; Dai, Sheng

2013-04-17

379

SEPARATION OF URANYL AND RUTHENIUM VALUES BY THE TRIBUTYL PHOSPHATE EXTRACTION PROCESS  

DOEpatents

A process is given for separating uranyl values from ruthenium values contained in an aqueous 3 to 4 M nitric acid solution. After the addition of hydrogen peroxide to obtain a concentration of 0.3 M, the uranium is selectively extracted with kerosene-diluted tributyl phosphate.

Wilson, A.S.

1961-05-01

380

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

381

THE SEPARATION AND FLUORESCENT X-RAY SPECTROMETRIC DETERMINATION OF ZIRCONIUM, MOLYBDENUM, RUTHENIUM, RHODIUM, AND PALLADIUM IN SOLUTION IN URANIUM-BASE FISSIUM ALLOYS  

Microsoft Academic Search

The various elements are separated prior to the fluorescent x-ray ; determination because of either direct x-ray line interference or negative ; interference to the characteristic x-ray intensities caused by the presence of ; the other elements in the solution. Palladium is precipitated with ; dimethylglyoxime, and the precipitate is extracted with chloroform. The aqueous ; portion is made 6M

J. O. Karttunen

1963-01-01

382

Conversion of depleted uranium hexafluoride to a solid uranium compound  

DOEpatents

A process for converting UF.sub.6 to a solid uranium compound such as UO.sub.2 and CaF. The UF.sub.6 vapor form is contacted with an aqueous solution of NH.sub.4 OH at a pH greater than 7 to precipitate at least some solid uranium values as a solid leaving an aqueous solution containing NH.sub.4 OH and NH.sub.4 F and remaining uranium values. The solid uranium values are separated from the aqueous solution of NH.sub.4 OH and NH.sub.4 F and remaining uranium values which is then diluted with additional water precipitating more uranium values as a solid leaving trace quantities of uranium in a dilute aqueous solution. The dilute aqueous solution is contacted with an ion-exchange resin to remove substantially all the uranium values from the dilute aqueous solution. The dilute solution being contacted with Ca(OH).sub.2 to precipitate CaF.sub.2 leaving dilute NH.sub.4 OH.

Rothman, Alan B. (Willowbrook, IL); Graczyk, Donald G. (Lemont, IL); Essling, Alice M. (Elmhurst, IL); Horwitz, E. Philip (Naperville, IL)

2001-01-01

383

URANIUM COMPOSITIONS  

DOEpatents

This patent relates to high purity uranium alloys characterized by improved stability to thermal cycling and low thermal neutron absorption. The high purity uranium alloy contains less than 0.1 per cent by weight in total amount of any ore or more of the elements such as aluminum, silicon, phosphorous, tin, lead, bismuth, niobium, and zinc.

Allen, N.P.; Grogan, J.D.

1959-05-12

384

URANIUM EXTRACTION  

Microsoft Academic Search

The recovery of uranium values from uranium ore such as pitchblende is ; described. The ore is first dissolved in nitric acid, and a water soluble ; nitrate is added as a salting out agent. The resulting feed solution is then ; contacted with diethyl ether, whereby the bulk of the uranyl nitrate and a ; portion of the impurities

C. D. Harrington; J. V. Opie

1958-01-01

385

Determination of uranium in zircon  

USGS Publications Warehouse

A routine fluorimetric procedure is described for the determination of trace amounts of uranium in zircon. It employs the direct extraction of uranyl nitrate with ethyl acetate using phosphate as a retainer for zirconium. Submicrogram amounts or uranium are separated in the presence of 100,000 times the amount of zirconium. The modified procedure has been worked out using synthetic mixtures of known composition and zircon. Results of analyses have an accuracy of 97-98% of the contained uranium and a standard deviation of less than 2.5%. ?? 1959.

Cuttitta, F.; Daniels, G. J.

1959-01-01

386

Uranium enrichment  

SciTech Connect

GAO was asked to address several questions concerning a number of proposed uranium enrichment bills introduced during the 100th Congress. The bill would have restructured the Department of Energy's uranium enrichment program as a government corporation to allow it to compete more effectively in the domestic and international markets. Some of GAO's findings discussed are: uranium market experts believe and existing market models show that the proposed DOE purchase of a $750 million of uranium from domestic producers may not significantly increase production because of large producer-held inventories; excess uranium enrichment production capacity exists throughout the world; therefore, foreign producers are expected to compete heavily in the United States throughout the 1990s as utilities' contracts with DOE expire; and according to a 1988 agreement between DOE's Offices of Nuclear Energy and Defense Programs, enrichment decommissioning costs, estimated to total $3.6 billion for planning purposes, will be shared by the commercial enrichment program and the government.

Not Available

1989-01-01

387

Experimental investigation of the permeability and selectivity of supported ionic liquid membranes for CO 2\\/He separation at temperatures up to 125 °C  

Microsoft Academic Search

Supported liquid membranes have been prepared by impregnation of commercial porous polymer films with the ionic liquid 1-n-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The ionic liquid has been characterized, and the membranes have been tested to determine performance in the selective separation of CO2 from He. Experiments were conducted in a constant pressure system, and pure gas permeability\\/selectivity data are reported. Membranes prepared with

Jeffery Ilconich; Christina Myers; Henry Pennline; David Luebke

2007-01-01

388

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

389

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, V.M. Jr.; Pullen, W.C.; Kollie, T.G.; Bell, R.T.

1981-10-21

390

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

2009-10-12

391

Smart thorium and uranium determination exploiting renewable solid-phase extraction applied to environmental samples in a wide concentration range.  

PubMed

A smart fully automated system is proposed for determination of thorium and uranium in a wide concentration range, reaching environmental levels. The hyphenation of lab-on-valve (LOV) and multisyringe flow injection analysis (MSFIA), coupled to a long path length liquid waveguide capillary cell, allows the spectrophotometric determination of thorium and uranium in different types of environmental sample matrices achieving high selectivity and sensitivity levels. Online separation and preconcentration of thorium and uranium is carried out by means of Uranium and TEtraValents Actinides resin. The potential of the LOV-MSFIA makes possible the full automation of the system by the in-line regeneration of the column and its combination with a smart methodology is a step forward in automation. After elution, thorium(IV) and uranium(VI) are spectrophotometrically detected after reaction with arsenazo-III. We propose a rapid, inexpensive, and fully automated method to determine thorium(IV) and uranium(VI) in a wide concentration range (0-1,200 and 0-2,000 ?g L(-1) Th and U, respectively). Limits of detection reached are 5.9 ?g L(-1) of uranium and 60 ?g L(-1) of thorium. Different water sample matrices (seawater, well water, freshwater, tap water, and mineral water), and a channel sediment reference material which contained thorium and uranium were satisfactorily analyzed with the proposed method. PMID:21573729

Avivar, Jessica; Ferrer, Laura; Casas, Montserrat; Cerdà, Víctor

2011-05-14

392

The use of amphoteric ion exchange resin for the selective separation of cadmium from other radioelements present in neutron irradiated biological materials  

Microsoft Academic Search

A new method for the selective radiochemical separation of cadmium from other elements, present in biological materials, using amphoteric ion exchange resin Retardion 11A8 has been elaborated. Cadmium can be taken up by the resin either as anionic chloride complexes or cationic ammine complexes, depending on the composition of the eluent, exploiting both cation and anion exchange functions of the

R. Dybczy?ski; Z. Samczy?ski

1991-01-01

393

Self-assembly molecularly imprinted polymers of 17?-estradiol on the surface of magnetic nanoparticles for selective separation and detection of estrogenic hormones in feeds  

Microsoft Academic Search

This paper reports a surface molecular self-assembly strategy for molecular imprinting on magnetic nanoparticles for selective separation and detection of estrogens in feeds. First, ?-methacryloxypropyltrimethoxysilane (MEMO) was successfully assembled at the surface magnetic nanoparticles through simple free radical polymerization, and subsequently, the copolymerization was further assembled between methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of templates

Shu Wang; Yun Li; Meijuan Ding; Xiaoli Wu; Jinhui Xu; Ruoyu Wang; Tingting Wen; Wenyu Huang; Ping Zhou; Kunfang Ma; Xuemin Zhou; Shuhu Du

2011-01-01

394

Selective separation of radio-cesium from acidic solutions using supported liquid membrane containing chlorinated cobalt dicarbollide (CCD) in phenyltrifluoromethyl sulphone (PTMS)  

Microsoft Academic Search

A supported liquid membrane method was developed using chlorinated cobalt dicarbollide (CCD) in phenyltrifluoromethyl sulphone (PTMS) as the carrier, impregnated in PTFE flat sheet membranes for the selective separation of Cs(I) from nitric acid feed solution. Solvent extraction studies were carried out for optimizing the feed as well as strip conditions. >95% Facilitated transport of Cs(I) was observed in about

P. K. Mohapatra; A. Bhattacharyya; V. K. Manchanda

2010-01-01

395

REMOVAL OF URANIUM FROM ORGANIC LIQUIDS  

DOEpatents

A process is described for recovering small quantities of uranium from organic liquids such as hydrocarbon oils. halogen-substituted hydrocarbons, and alcohols. The organic liquid is contacted with a comminuted alkaline earth hydroxide, calcium hydroxide particularly, and the resulting uranium-bearing solid is separated from the liquid by filtration. Uranium may then be recovered from the solid by means of dissolution in nitric acid and conventional extraction with an organic solvent such as tributyl phosphate.

Vavalides, S.P.

1959-08-25

396

Application of carboxymethyl-?-cyclodextrin as a chiral selector in capillary electrophoresis for enantiomer separation of selected neurotransmitters  

Microsoft Academic Search

The aim of this work was to optimize conditions for capillary electrophoresis separation of different neurotransmitters (serotonin, phenylalanine, dopamine, adrenaline, ephedrine, propranolol and DOPA) in a single run, including separation of existing enantiomers. As chiral selectors added to the borate background, electrolyte unsubstituted ?-, ?- and ?-cyclodextrins (CDs), methyl-, dimethyl-, and trimethyl-substituted ?-CDs, and hydroxypropyl-substituted ?-, ?- and ?-CDs were

Wioleta Maruszak; Marek Trojanowicz; Magdalena Margasi?ska; Hans Engelhardt

2001-01-01

397

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

398

URANIUM DECONTAMINATION WITH RESPECT TO ZIRCONIUM  

DOEpatents

A process is given for separating uranium values from a nitric acid aqueous solution containing uranyl values, zirconium values and tetravalent plutonium values. The process comprises contacting said solution with a substantially water-immiscible liquid organic solvent containing alkyl phosphate, separating an organic extract phase containing the uranium, zirconium, and tetravalent plutonium values from an aqueous raffinate, contacting said organic extract phase with an aqueous solution 2M to 7M in nitric acid and also containing an oxalate ion-containing substance, and separating a uranium- containing organic raffinate from aqueous zirconium- and plutonium-containing extract phase.

Vogler, S.; Beederman, M.

1961-05-01

399

OXALATE PROCESS FOR SEPARATING ELEMENT 94  

DOEpatents

A process is presented for separating plutonium values in the tetravalent state from hexavalent uranium with which it is associated in aqueous solutions. This separation is aceomplished by forming a thorium oxalate precipitate in order to carry only the plutonium. By carefully regulating the acidity of the solution and the oxalate ion concentration, the precipitation of uranium oxalate may be avoided.

Gofman, J.W.

1959-01-01

400

Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lowman, Idaho: Remedial action selection report for the Lowman UMTRA project site, Idaho  

SciTech Connect

The inactive uranium mill tailings site near Lowman, Idaho, was designated as one of 24 abandoned uranium tailings sites to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). The UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's remedial action plan and certify that the remedial action complies with the standards promulgated by the US Environmental Protection Agency (EPA). The remedial action plan (RAP), which includes this remedial action selection report (RAS), has been developed to serve a two-fold purpose. First, it describes the activities that are proposed by the DOE to accomplish long-term stabilization and control of residual radioactive materials at the inactive uranium processing site near Lowman, Idaho. Second, this document and the remainder of the RAP, upon concurrence and execution by the DOE, the State of Idaho, and the NRC, becomes Appendix B of the Cooperative Agreement (No. DE-FC04-85AL20535) between the DOE and the State of Idaho.

Matthews, M.L. (USDOE Albuquerque Field Office, NM (United States). Uranium Mill Tailings Remedial Action Project Office); Nagel, J. (Idaho Dept. of Health and Welfare, Boise, ID (United States). Div. of Environmental Quality)

1991-09-01

401

Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lowman, Idaho: Remedial action selection report for the Lowman UMTRA project site, Idaho. Final report  

SciTech Connect

The inactive uranium mill tailings site near Lowman, Idaho, was designated as one of 24 abandoned uranium tailings sites to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). The UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE`s remedial action plan and certify that the remedial action complies with the standards promulgated by the US Environmental Protection Agency (EPA). The remedial action plan (RAP), which includes this remedial action selection report (RAS), has been developed to serve a two-fold purpose. First, it describes the activities that are proposed by the DOE to accomplish long-term stabilization and control of residual radioactive materials at the inactive uranium processing site near Lowman, Idaho. Second, this document and the remainder of the RAP, upon concurrence and execution by the DOE, the State of Idaho, and the NRC, becomes Appendix B of the Cooperative Agreement (No. DE-FC04-85AL20535) between the DOE and the State of Idaho.

Matthews, M.L. [USDOE Albuquerque Field Office, NM (United States). Uranium Mill Tailings Remedial Action Project Office; Nagel, J. [Idaho Dept. of Health and Welfare, Boise, ID (United States). Div. of Environmental Quality

1991-09-01

402

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; 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 US Department of Energy (DOE) under Title I of the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). The UMTRCA requires that the US 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 US 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.

Chernoff, A.R. [USDOE Albuquerque Field Office, NM (United States). Uranium Mill Tailings Remedial Action Project Office; Lacker, D.K. [Texas State Dept. of Health, Austin, TX (United States). Bureau of Radiation Control

1992-09-01

403

Do diatom algae frustules accumulate uranium?  

Microsoft Academic Search

Neutron Activation Analysis (NAA) and Synchrotron Radiation X-ray Fluorescent Analysis (SRXRFA) were used to measure the content of uranium and a few other trace elements in samples of bottom sediments of Lake Baikel separated into biogenic (diatom algae frustules) and clastic components by an aerodynamic method. Uranium is rejected, rather than accumulated by diatom algae frustules.

E. L. Goldberg; M. A. Grachev; V. A. Bobrov; A. V. Bessergenev; B. V. Zolotaryov; Ye. V. Likhoshway

1998-01-01

404

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...

405

Plutonium recovery from spent reactor fuel by uranium displacement  

Microsoft Academic Search

A process for separating uranium values and transuranic values from fission products containing rare earth values when the values 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

Ackerman; John P

1992-01-01

406

Plutonium recovery from spent reactor fuel by uranium displacement  

Microsoft Academic Search

A process is described for separating uranium values and transuranic values from fission products containing rare earth values when the values 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

Ackerman

1992-01-01

407

Effect of anionic ion-pairing reagent hydrophobicity on selectivity of peptide separations by reversed-phase liquid chromatography  

Microsoft Academic Search

Despite the continuing dominance of trifluoroacetic acid (TFA) as the anionic ion-pairing reagent of choice for peptide separations by reversed-phase high-performance liquid chromatography (RP-HPLC), we believe that a step-by-step approach to re-examining the relative efficacy of TFA compared to other ion-pairing reagents is worthwhile, particularly for the design of separation protocols for complex peptide mixtures, e.g., in proteomics applications. Thus,

M. Shibue; C. T. Mant; R. S. Hodges

2005-01-01

408

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

409

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

2012-02-06

410

ELUTION OF URANIUM FROM RESIN  

DOEpatents

A method is described for eluting uranium from anion exchange resins so as to decrease vanadium and iron contamination and permit recycle of the major portion of the eluats after recovery of the uranium. Diminution of vanadium and iron contamination of the major portion of the uranium is accomplished by treating the anion exchange resin, which is saturated with uranium complex by adsorption from a sulfuric acid leach liquor from an ore bearing uranium, vanadium and iron, with one column volume of eluant prepared by passing chlorine into ammonium hydroxide until the chloride content is about 1 N and the pH is about 1. The resin is then eluted with 8 to 9 column volumes of 0.9 N ammonium chloride--0.1 N hydrochloric acid solution. The eluants are collected separately and treated with ammonia to precipitate ammonium diuranate which is filtered therefrom. The uranium salt from the first eluant is contaminated with the major portion of ths vanadium and iron and is reworked, while the uranium recovered from the second eluant is relatively free of the undesirable vanadium and irons. The filtrate from the first eluant portion is discarded. The filtrate from the second eluant portion may be recycled after adding hydrochloric acid to increase the chloride ion concentration and adjust the pH to about 1.

McLEan, D.C.

1959-03-10

411

Detection of uranium enrichment activities using environmental monitoring techniques  

SciTech Connect

Uranium enrichment processes have the capability of producing weapons-grade material in the form of highly enriched uranium. Thus, detection of undeclared uranium enrichment activities is an international safeguards concern. The uranium separation technologies currently in use employ UF{sub 6} gas as a separation medium, and trace quantities of enriched uranium are inevitably released to the environment from these facilities. The isotopic content of uranium in the vegetation, soil, and water near the plant site will be altered by these releases and can provide a signature for detecting the presence of enriched uranium activities. This paper discusses environmental sampling and analytical procedures that have been used for the detection of uranium enrichment facilities and possible safeguards applications of these techniques.

Belew, W.L.; Carter, J.A.; Smith, D.H.; Walker, R.L.

1993-03-30

412

Solid-vapor sorption of xylenes: prioritized selectivity as a means of separating all three isomers using a single substrate.  

PubMed

A Werner complex is highly selective for o-xylene in a vapor mixture containing all three isomers. However, in the absence of o-xylene, the substrate shows similar selectivity for m-xylene over p-xylene. Kinetic studies show a different trend whereby m-xylene is absorbed most rapidly, implying that thermodynamic factors must be responsible for the selectivity. PMID:22411768

Lusi, Matteo; Barbour, Leonard J

2012-03-12

413

Oil separator  

SciTech Connect

An oil separator is described for use at the scene of an oil spill. It features a tank divided by imperforate bulkheads into a folded, horizontal flow path, the flow path being further divided by perforate baffles through which the flow passes, the baffles having apertures selected to pass debris but also provide wave damping and evening of flow velocities.

Milgram, J.H.

1981-06-02

414

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

415

Response to domestication and selection for growth in the European sea bass ( Dicentrarchus labrax) in separate and mixed tanks  

Microsoft Academic Search

Selective breeding of European sea bass (Dicentrarchus labrax) receives a growing interest, as the estimated heritability of growth is medium to high. In this study, we compared the offspring of four groups of sea bass sires, mated with the same wild dams: wild (W), first generation of domestication (D), first generation of mass selection for length (M), first generation of

Marc Vandeputte; Mathilde Dupont-Nivet; Pierrick Haffray; Hervé Chavanne; Silvia Cenadelli; Katia Parati; Marie-Odile Vidal; Alain Vergnet; Béatrice Chatain

2009-01-01

416

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

417

Amide Grafted Amberlite XAD?16 Polymer for the Selective and Sequential Separation of U(VI) and Th(IV) from Acidic Waste Effluents  

Microsoft Academic Search

The newly developed amide grafted polymer, p?amino?N,N?dihexylacetamide (ADHA) anchored on Amberlite XAD?16 (polystyrene?divinylbenzene co?polymer) solid support, shows greater selectivity in extracting U(VI) over Th(IV) and lanthanides from highly acidic matrices. It serves as an efficient solid phase extractant to perform an extraction chromatographic separation of U\\/Th. The grafting process is monitored by C?CPMAS NMR spectroscopy, FT?NIR spectroscopy, and CHN elemental

M. Akhila Maheswari; M. S. Subramanian

2005-01-01

418

Selective separation of nickel from cobalt in ammoniacal solutions by emulsion type liquid membranes using 8-hydroxyquinoline (8HQ) as mobile carrier  

Microsoft Academic Search

The selective separation and concentration of nickel from ammoniacal solutions containing nickel and cobalt by an emulsion liquid membrane (ELM) technique using 8-hydroxyquinoline (8-HQ) as carrier has been examined. The emulsion liquid membrane consists of a diluent (kerosene), a surfactant (ECA 4360J), a carrier (8-HQ), and a stripping solution (0.025 M EDTA solution, buffered at pH 4.0). Cobalt (II) in the

R. A. Kumbasar; S. Kasap

2009-01-01

419

A comparative study of the metal selective properties of chelating dye impregnated resins for the ion chromatographic separation of trace metals  

Microsoft Academic Search

Summary  High-performance chelation ion chromatography (HPCIC) involving the use of chelating dye impregnated resins has been investigated for its ability to preconcentrate and separate a range of metals in a variety of complex samples. The parameters involved in the production of dye impregnated chelating columns have been identified and investigated. A number of selected chelating dyes have been impregnated into high-performance

B. Paull; P. Jones

1996-01-01

420

Separation and selective detection of lipoprotein particles of patients with coronary artery disease by frit-inlet asymmetrical flow field-flow fractionation  

Microsoft Academic Search

An analytical method to improve the characterization of lipoprotein fractions is presented. Human plasma samples were treated with Sudan Black B to stain the lipid component in lipoproteins, then the stained lipoproteins were separated by frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF), according to the lipoprotein particle sizes, with the selective detection of eluting lipoprotein fractions, high-density lipoproteins (HDL), low-density

Ki-Jung Paeng; Yeomin Yoon; Jung-Han Song; Myeong Hee Moon

2002-01-01

421

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

422

Expression profilings of 39 genes selected by ANOVA could separate precursors of murine dendritic cells and macrophages  

Microsoft Academic Search

Dendritic cells (DCs) and macrophages share some stages in the development and function of antigen presentation. But it is difficult to separate them from their precursors. We used one-way ANOVA (analysis of variances) on murine expression profilings of several hematopoietic cells associated with DCs and macrophages to find the genes with great differences across the cell groups. These groups were

Shixin Zhou; Yuqin Liu; Hong Bo; Xiaocui Bian; Xiaojun Xia; Changsheng Lin; Vincent Wai-Sun Wong; Zuhong Lu

2006-01-01

423

Separated Families and Children Who Refuse Access to a Parent. Unit for Child Studies Selected Papers Number 33.  

ERIC Educational Resources Information Center

On the whole, professionals agree that there is an advantage in both parents having access to the child or children after separation. This paper provides (1) an overview of the controversy over the value of such access; (2) a description of various contexts of access disputes and perspectives involved in the assessment of access situations; (3) a…

Renouf, Emilia

424

METHOD FOR REFINING AND SEPARATING A METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM, ZIRCONIUM, CERIUM, HAFNIUM AND THORIUM  

Microsoft Academic Search

A method for refining and separating Ti, Zr, Ce, Hf, and Th is given ; which involves distillation of carbonyl complexes. Powdered Ti, for example, is ; agitated and heated in a vessel to 400 ction prod- C at a pressure of 4 to 8 ; atm. of a rare gas and enough CO to react to form liquid Ti(CO)â.

S. T. Jazwinski; J. A. Sisto

1960-01-01

425

Effect of anionic ion-pairing reagent hydrophobicity on selectivity of peptide separations by reversed-phase liquid chromatography  

PubMed Central

Despite the continuing dominance of trifluoroacetic acid (TFA) as the anionic ion-pairing reagent of choice for peptide separations by reversed-phase high-performance liquid chromatography (RP-HPLC), we believe that a step-by-step approach to re-examining the relative efficacy of TFA compared to other ion-pairing reagents is worthwhile, particularly for the design of separation protocols for complex peptide mixtures, e.g., in proteomics applications. Thus, we applied RP-HPLC in the presence of different concentrations of anionic ion-pairing reagents – phosphoric acid, TFA, pentafluoropropionic acid (PFPA) and heptafluorobutyric acid (HFBA) – to a mixture of three groups of four 10-residue peptides, these groups containing peptides of +1, +3 or +5 net charge. Overall separation of the 12-peptide mixture improved with increasing reagent hydrophobicity (phosphate? < TFA? < PFPA? < HFBA?) and/or concentration of the anion, with reagent hydrophobicity having a considerably more pronounced effect than reagent concentration. HFBA, in particular, achieved an excellent separation at a concentration of just 10 mM, whereby the peptides were separated by charged groups (+1 < +3 < +5) and hydrophobicity within these groups. There was an essentially equal effect of reagent hydrophobicity and concentration on each positive charge of the peptides, a useful observation for prediction of the effect of varying counterion concentration hydrophobicity and/or concentration during optimization of peptide purification protocols. Peak widths were greater for the more highly charged peptides, although these could be decreased significantly by raising the acid concentration; concomitantly, peptide resolution increased with increasing concentration of ion-pairing reagent.

Shibue, M.; Mant, C.T.; Hodges, R.S.

2009-01-01

426

Effect of anionic ion-pairing reagent hydrophobicity on selectivity of peptide separations by reversed-phase liquid chromatography.  

PubMed

Despite the continuing dominance of trifluoroacetic acid (TFA) as the anionic ion-pairing reagent of choice for peptide separations by reversed-phase high-performance liquid chromatography (RP-HPLC), we believe that a step-by-step approach to re-examining the relative efficacy of TFA compared to other ion-pairing reagents is worthwhile, particularly for the design of separation protocols for complex peptide mixtures, e.g., in proteomics applications. Thus, we applied RP-HPLC in the presence of different concentrations of anionic ion-pairing reagents - phosphoric acid, TFA, pentafluoropropionic acid (PFPA) and heptafluorobutyric acid (HFBA)--to a mixture of three groups of four 10-residue peptides, these groups containing peptides of +1, +3 or +5 net charge. Overall separation of the 12-peptide mixture improved with increasing reagent hydrophobicity (phosphate- < TFA- < PFPA- < HFBA-) and/or concentration of the anion, with reagent hydrophobicity having a considerably more pronounced effect than reagent concentration. HFBA, in particular, achieved an excellent separation at a concentration of just 10 mM, whereby the peptides were separated by charged groups (+1 < +3 < +5) and hydrophobicity within these groups. There was an essentially equal effect of reagent hydrophobicity and concentration on each positive charge of the peptides, a useful observation for prediction of the effect of varying counterion concentration hydrophobicity and/or concentration during optimization of peptide purification protocols. Peak widths were greater for the more highly charged peptides, although these could be decreased significantly by raising the acid concentration; concomitantly, peptide resolution increased with increasing concentration of ion-pairing reagent. PMID:16013616

Shibue, M; Mant, C T; Hodges, R S

2005-07-01

427

Recovery of uranium from solutions  

Microsoft Academic Search

A process is described of separating uranium from a dilute waste solution derived from the ammonium diuranate process of converting UFâ to UOâ and containing U(VI), fluoride ion, and ammonium ion, which comprises adding sodium hydrosulfite to the solution and recovering a precipitate containing fluorine, sodium, ammonium, and U(IV).

R. A. Hermens; J. B. Kendall; J. A. Partridge

1987-01-01

428

METHOD OF PURIFYING URANIUM METAL  

DOEpatents

The removal of lmpurities from uranlum metal can be done by a process conslstlng of contacting the metal with liquid mercury at 300 icient laborato C, separating the impunitycontalnlng slag formed, cooling the slag-free liquld substantlally below the point at which uranlum mercurlde sollds form, removlng the mercury from the solids, and recovering metallic uranium by heating the solids.

Blanco, R.E.; Morrison, B.H.

1958-12-23

429

Uranium enrichment: technology, economics, capacity  

Microsoft Academic Search

Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being

W. R. Jr. Voigt; P. R. Vanstrum; D. E. Saire; D. K. Gestson; S. E. Peske

1982-01-01

430

Environmental Planning in Uranium Milling.  

National Technical Information Service (NTIS)

Effluents from uranium milling in the Achala region in the province of Cordoba are studied. Liquids from lixiviation-recovery and from precipitation-washing of yellow-cake were analyzed. Separation of both liquids before treatment and disposal is recommen...

L. F. Bertello

1987-01-01

431

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

432

Evaluation of Cyclodextrins as Chiral Selectors in the Separation of Selected Monoterpenes by Capillary Liquid Chromatography and Capillary Electrophoresis  

Microsoft Academic Search

Two techniques are evaluated in this paper for the separation of chiral monoterpenes commonly present in citrus: capillary liquid chromatography (C?LC) and capillary electrophoresis (CE). The utilization of cyclodextrins, as additive in the mobile phase (C?LC), and in the buffer (CE) was verified. It was observed, that the analytes interacted with methyl???cyclodextrin (met???CD), since the addition of cyclodextrin promoted alteration

C. A. Diagone; C. A. Ogawa; F. M. Lanças

2003-01-01

433

A Phos-tag-based magnetic-bead method for rapid and selective separation of phosphorylated biomolecules.  

PubMed

A simple and efficient method based on magnetic-bead technology has been developed for the separation of phosphorylated and nonphosphorylated low-molecular-weight biomolecules, such as nucleotides, phosphorylated amino acids, or phosphopeptides. The phosphate-binding site on the bead is an alkoxide-bridged dinuclear zinc(II) complex with 1,3-bis(pyridin-2-ylmethylamino)propan-2-olate (Phos-tag), which is linked to a hydrophilic cross-linked agarose coating on a magnetic core particle. All steps for the phosphate-affinity separation are conducted in buffers of neutral pH with 50 ?L of the magnetic beads in a 1.5-mL microtube. The entire separation protocol for phosphomonoester-type compounds, from addition to elution, requires less than 12 min per sample if the buffers and the zinc(II)-bound Phos-tag magnetic beads have been prepared in advance. The phosphate-affinity magnetic beads are reusable at least 15 times without a decrease in their phosphate-binding ability and they are stable for three months in propan-2-ol. PMID:23523882

Tsunehiro, Masaya; Meki, Yuma; Matsuoka, Kanako; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

2013-03-08

434

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

435

Membrane gas separation processes  

Microsoft Academic Search

A membrane gas separator apparatus is described for recovering a methane-enriched non-permeate gas from a mixture comprising methane and carbon dioxide. The apparatus consists of at least one first separator having a membrane exhibiting selectivity to the permeation of carbon dioxide; at least one subsequent separator having a membrane exhibiting selectivity to the permeation of carbon dioxide; a combustion engine

1986-01-01

436

Experimental investigation of the permeability and selectivity of supported ionic liquid membranes for CO2/He separation at temperatures up to 125° C  

SciTech Connect

Supported liquid membranes have been prepared by impregnation of commercial porous polymer films with the ionic liquid 1-n-hexyl-3- methylimidazolium bis(trifluoromethanesulfonyl)imide. The ionic liquid has been characterized, and the membranes have been tested to determine performance in the selective separation of CO2 from He. Experiments were conducted in a constant pressure system, and pure gas permeability/selectivity data are reported. Membranes prepared with polysulfone supports have been found to be stable to 125 °C. The CO2 permeability of the membranes increases from 744 to 1200 barrer as the temperature increases from 37 to 125 °C. The CO2/He selectivity decreased from 8.7 to 3.1 over the same temperature range.

Ilconich, J.B.; Myers, C.R.; Pennline, H.W.; Luebke, D.R.

2007-07-01

437

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

438

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

2011-04-12

439

Rescuing a Treasure Uranium-233  

SciTech Connect

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 for accurately quantifying and characterizing natural uranium isotopes for domestic and international safeguards. Separated 233U is stored in vaults at Oak Ridge National Laboratory. These materials represent a broad spectrum of 233U from the standpoint isotopic purity the purest being crucial for precise analyses in safeguarding uranium. All 233U at ORNL currently is scheduled to be down blended with depleted uranium beginning in 2015. Such down blending will permanently destroy the potential value of pure 233U samples as certified reference material for use in uranium analyses. Furthermore, no replacement 233U stocks are expected to be produced in the future due to a lack of operating production capability and the high cost of returning to operation this currently shut down capability. This paper will describe the efforts to rescue the purest of the 233U materials arguably national treasures from their destruction by down blending.

Krichinsky, Alan M [ORNL; Goldberg, Dr. Steven A. [DOE SC - Chicago Office; Hutcheon, Dr. Ian D. [Lawrence Livermore National Laboratory (LLNL)

2011-01-01

440

URANIUM ALLOYS  

DOEpatents

Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

Seybolt, A.U.

1958-04-15

441

Packed-column supercritical fluid chromatography: Quantitative determination of uranium without liquid waste generation  

SciTech Connect

A new procedure for the determination of uranium by packed-column supercritical fluid chromatography is proposed. A nonfluorinated chelating agent selective for copper and uranium, the 2,6-diacetylpyridine bis(benzoylhydrazone), has been chosen. We have studied its chromatographic properties on different stationary phases and the influence of the methanol content in the carbon dioxide mobile phase. The separation of the metal compounds was conducted with and without solvent injection. A calibration curve was obtained for uranium in the range of 52-323 ng injected. The accuracy of the method is 0.5%, the repeatability 4%. The same studies were performed with a new compound, diacetyl-2,6 pyridine bis(4-tert-butyl benzoylhydrazone). An increase in retention and efficiency was then observed. 30 refs., 5 figs., 3 tabs.

Martin-Daguet, V. [Commissariat a l`Energie Atomique, Gif sur Yvette (France); Gasnier, P. [Cogema, Bagnols sur Ceze (France); Caude, M. [Ecole Superieure de physique et de Chimie Industrielles de la ville de Paris, Paris (France)

1997-02-01

442

Remedial action plan and site design for stabilization of the inactive uranium processing site at Naturita, Colorado. Remedial Action Selection Report, Appendix B of Attachment 2: Geology report, Final  

SciTech Connect

The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the US 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 US 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 US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which describes the proposed remedial action for the Naturita site. An extensive amount of data and supporting information has been generated and evaluated for this remedial action. These data and supporting information are not incorporated into this single document but are included or referenced in the supporting documents. The RAP consists of this RAS and four supporting documents or attachments. This Attachment 2, Geology Report describes the details of geologic, geomorphic, and seismic conditions at the Dry Flats disposal site.

Not Available

1994-03-01

443

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

444

SEPARATION OF TECHNETIUM99 FROM URANIUM HEXAFLUORIDE  

Microsoft Academic Search

A system is described for recovery of Tc from UFâ in a UOâ fluorination plant. The Tc is retained on MgFâ in traps through which the UFâ stream is passed. The system is in operation at the Paducah Gaseous Diffusion Plant. (J.R.D.)

W. R. Golliher; R. A. LeDoux; S. Bernstein; V. A. Smith

1963-01-01

445

A novel molecularly imprinted polymer of the specific ionic liquid monomer for selective separation of synephrine from methanol-water media.  

PubMed

A novel molecularly imprinted polymer (MIP) using the specific ionic liquid (i.e. 1-vinyl-3-carboxymethylimidazolium bromide, 1-vinyl-3-carboxyethylimidazolium bromide, 1-viny-3-carboxybutylimidazolium bromide, or 1-vinyl-3-carboxypentylimidazolium bromide) as functional monomer was prepared via precipitation polymerization, which can be used to selectively separate synephrine (SYN) from methanol-water media. Ionic liquids are facile to be designed with varying the cation or anion, which enables the specific ionic liquid to be effectively designed to be a functional monomer for the preparation of MIP. The MIP showed a good selectivity and high adsorption capacity for SYN in methanol-water media. The adsorption process could be described by the pseudo-first-order model, which meant that the adsorption kinetics described a diffusion-controlled process. The equilibrium data fitted well to the Freundlich model, indicating multilayer adsorption. Finally, the MIP were successfully applied as sorbent to selectively enrich and separate SYN from the extracts of Aurantii Fructus Immaturus with a relatively high recovery (80-90%). PMID:23993524

Fan, Jie-Ping; Tian, Ze-You; Tong, Sheng; Zhang, Xue-Hong; Xie, Yan-Long; Xu, Rui; Qin, Yu; Li, Lie; Zhu, Jian-Hang; Ouyang, Xiao-Kun

2013-06-20

446

Selective extraction, separation, and identification of anthocyanins from Hibiscus sabdariffa L. using solid phase extraction-capillary electrophoresis-mass spectrometry (time-of-flight /ion trap).  

PubMed

A method for selective extraction using SPE, electrophoretic separation at basic condition and the identification by using exact masses and fragmentation patterns has been developed in order to know the anthocyanins in dried calyces of Hibiscus sabdariffa L. A detailed and comparative study of several extraction procedures has been carried out to obtain the maximum number of anthocyanidins from the calyces and then a CE-TOF-MS method in positive mode using ESI has been developed for the separation and rapid identification of anthocyanins in H. sabdariffa L. Delphinidin-3-sambubioside, cyanidin-3-sambubioside have been detected as main components and cyanidin-3-O-rutinoside, delphinidin-3-O-glucoside and cyanidin-3,5-diglucoside, and chlorogenic acid as minor constituents. The confirmation of the anthocyanidins and chlorogenic acid was carried out using fragmentation ions with the IT-mass spectrometer (IT-MS). PMID:18546170

Segura-Carretero, Antonio; Puertas-Mejía, Miguel A; Cortacero-Ramírez, Sonia; Beltrán, Raúl; Alonso-Villaverde, Carlos; Joven, Jorge; Dinelli, Giovanni; Fernández-Gutiérrez, Alberto

2008-07-01

447

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