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

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

2

The use of selective extraction chromatographic columns as an alternative to solvent extraction for the separation of uranium followed by the use of Arsenazo III as a calorimetric reagent for uranium determination  

SciTech Connect

The use of U/TEVA{reg_sign} Spec columns as an alternative to solvent extraction for separation of uranium prior to its determination by various techniques (calorimetric, phosphorescence, and mass spectroscopy) was investigated. U/TEVA{reg_sign} Spec columns have several advantages over the widely used 4-methyl-2-pentanone solvent extraction method. Among the advantages are: (1) no hazardous liquid organic waste, that creates regulatory waste disposal problems, is generated; (2) a clean separation of U from Zr, F, and fission products is obtained; (3) the sample preparation time is reduced; and (4) the exposure of analysts to ionizing radiation is reduced because the entire procedure may be performed in a hot cell using remote operations. This study also investigated the use of Arsenazo III (1,8-dihydroxynapthalene-3,6-disulfonic acid-2,7-bis [<-azo-2>-phenylarsonic acid]) as a calorimetric reagent to determine uranium concentrations over a wide range in waste streams and product streams at the Idaho Chemical Processing Plant. Process and waste stream samples were passed through a U/TEVA{reg_sign} Spec column to selectively remove the uranium. The uranium bearing fraction is compatible with the pH range for color development with Arsenazo III. Arsenazo III may be added to the uranium fraction, at a 3:1 mole ratio (Arsenazo:Uranium) at the high end of the method (10 {mu}/mL). Arsenazo III forms a highly stable complex with uranium. Stability tests from this and other studies show that the colored complex of Arsenazo III with U(VI) forms within one minute and remains stable for several hours. The complex with U(VI) varies in color with pH. However, with excess reagent, the color is varying shades of purple. Since the samples were passed through a highly selective extraction chromatographic column prior to adding the calorimetric reagent, no interferences were observed.

Miller, C.J.; Del Mastro, J.R.

1994-10-01

3

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

Microsoft Academic Search

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

Shinichi Suzuki; Yumi Sugo; Takaumi Kimura; Tsuyoshi Yaita

2007-01-01

4

A novel benzimidazole-functionalized 2-D COF material: synthesis and application as a selective solid-phase extractant for separation of uranium.  

PubMed

A novel COF-based material (COF-COOH) containing large amounts of carboxylic groups was prepared for the first time by using a simple and effective one-step synthetic method, in which the cheap and commercially available raw materials, trimesoyl chloride and p-phenylenediamine, were used. The as-synthesized COF-COOH was modified with previously synthesized 2-(2,4-dihydroxyphenyl)-benzimidazole (HBI) by "grafting to" method, and a new solid-phase extractant (COF-HBI) with highly efficient sorption performance for uranium(VI) was consequently obtained. A series of characterizations demonstrated that COF-COOH and COF-HBI exhibited great thermostabilities and irradiation stabilities. Sorption behavior of the COF-based materials toward U(VI) was compared in simulated nuclear industrial effluent containing UO2(2+) and 11 undesired ions, and the UO2(2+) sorption amount of COF-HBI was 81 mg g(-1), accounting for approximately 58% of the total sorption amount, which was much higher than the sorption selectivity of COF-COOH to UO2(2+) (39%). Batch sorption experiment results indicated that the uranium(VI) sorption on COF-HBI was a pH dependent, rapid (sorption equilibrium was reached in 30 min), endothermic and spontaneous process. In the most favorable conditions, the equilibrium sorption capacity of the adsorbent for uranium could reach 211 mg g(-1). PMID:25313486

Li, Juan; Yang, Xiaodan; Bai, Chiyao; Tian, Yin; Li, Bo; Zhang, Shuang; Yang, Xiaoyu; Ding, Songdong; Xia, Chuanqin; Tan, Xinyu; Ma, Lijian; Li, Shoujian

2015-01-01

5

Chemical separation method for uranium isotopes  

Microsoft Academic Search

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

S. H. Peterson; D. C. Phillips

1986-01-01

6

Separation of Zirconium from Uranium in U-Zr Alloys Using a Chlorination Process  

E-print Network

The fundamental behavior underpinning a new processing concept was demonstrated which is capable of separating uranium from zirconium in U-Zr alloys through the formation and selective volatilization of their respective chlorides. Bench...

Parkison, Adam J

2013-06-04

7

Innovative lasers for uranium isotope separation. [Progress report  

Microsoft Academic Search

Copper vapor lasers have important applications to uranium atomic vapor laser isotope separation (AVLIS). The authors have spent the first two years of their project investigating two innovative methods of exciting\\/pumping copper vapor lasers which have the potential to improve the efficiency and scaling of large laser systems used in uranium isotope separation. Experimental research has focused on the laser

M. L. Brake; R. M. Gilgenbach

1991-01-01

8

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

9

Pulsed CO laser for isotope separation of uranium  

SciTech Connect

This article proposes a technical solution for using a CO laser facility for the industrial separation of uranium used in the production of fuel for nuclear power plants, employing a method of laser isotope separation of uranium with condensation repression in a free jet. The laser operation with nanosecond pulse irradiation can provide an acceptable efficiency in the separating unit and a high efficiency of the laser with the wavelength of 5.3 {mu}m. In the present work we also introduce a calculation model and define the parameters of a mode-locked CO laser with a RF discharge in the supersonic stream. The average pulsed CO laser power of 3 kW is sufficient for efficient industrial isotope separation of uranium in one stage.

Baranov, Igor Y.; Koptev, Andrey V. [Rocket-Space Technics Department, Baltic State Technical University, 1, 1st Krasnoarmeyskaya st.,St. Petersburg, 190005 (Russian Federation)

2012-07-30

10

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

11

CO-laser-induced photochemical reaction of UF6 with HCl for the isotope separation of uranium hexafluoride  

NASA Astrophysics Data System (ADS)

In this paper, we report the results of CO-laser induced photochemical reaction of UF6 with HCl for the isotope separation of uranium hexafluoride, we also discussed that the molecular collision inducing V-T, V-V relaxation process affects on the selectivity of the isotope separation. The obtained quantum coefficiency of the reaction is about 0.34.

Ding, Hong-Bin; Shen, Z. Y.; Zhang, Cun H.

1993-05-01

12

Supercritical Fluid Extraction and Separation of Uranium from Other Actinides  

SciTech Connect

This paper investigates the feasibility of separating uranium from other actinides by using supercritical fluid carbon dioxide (sc-CO2) as a solvent modified with tri-n-butylphosphate (TBP) for the development of an extraction and counter current stripping technique, which would be a more efficient and environmentally benign technology for used nuclear fuel reprocessing compared to traditional solvent extraction. Several actinides (U(VI), Np(VI), Pu(IV), and Am(III)) were extracted in sc-CO2 modified with TBP over a range of nitric acid concentrations and then the actinides were exposed to reducing and complexing agents to suppress their extractability. According to this study, the separation of uranium from plutonium in sc-CO2 modified with TBP was successful at nitric acid concentrations of less than 3 M in the presence of acetohydroxamic acid or oxalic acid, and the separation of uranium from neptunium was successful at nitric acid concentrations of less than 1 M in the presence of acetohydroxamic acid, oxalic acid, or sodium nitrite.

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

2014-06-01

13

Separation and spectrophotometric determination of uranium (VI) by extraction with arsenazo III and zephiramine  

Microsoft Academic Search

Summary Microgram quantities of uranium(VI) can be determined at 655 nm after separation by chloroform extraction of its Arsenazo III complex with Zephiramine. The extracted uranium can be back-extracted with an aqueous solution of ammonium carbonate. Uranium can be separated from aluminium, iron(II), and some other elements. Probably the same species, i. e., the ion association compound between the uranium

Keiichi Sekine

1976-01-01

14

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

15

Innovative lasers for uranium isotope separation. [Progress report  

SciTech Connect

Copper vapor lasers have important applications to uranium atomic vapor laser isotope separation (AVLIS). The authors have spent the first two years of their project investigating two innovative methods of exciting/pumping copper vapor lasers which have the potential to improve the efficiency and scaling of large laser systems used in uranium isotope separation. Experimental research has focused on the laser discharge kinetics of (1) microwave, and (2) electron beam excitation/pumping of large-volume copper vapor lasers. During the first year, the experiments have been designed and constructed and initial data has been taken. During the second year these experiments have been diagnosed. Highlights of some of the second year results as well as plans for the future include the following: Microwave resonant cavity produced copper vapor plasmas at 2.45 GHz, have been investigated. A CW (0--500 W) signal heats and vaporizes the copper chloride to provide the atomic copper vapor. A pulsed (5 kW, 0.5--5kHz) signal is added to the incoming CW signal via a hybrid mixer to excite the copper states to the laser levels. An enhancement of the visible radiation has been observed during the pulsed pardon of the signal. Electrical probe measurements have been implemented on the system to verify the results of the electromagnetic model formulated last year. Laser gain measurements have been initiated with the use of a commercial copper vapor laser. Measurements of the spatial profile of the emission are also currently being made. The authors plan to increase the amount of pulsed microwave power to the system by implementing a high power magnetron. A laser cavity will be designed and added to this system.

Brake, M.L.; Gilgenbach, R.M.

1991-06-01

16

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

17

Separation of uranium from nitric and hydrochloric acid solutions with extractant-coated magnetic microparticles.  

SciTech Connect

The magnetically assisted chemical separation (MACS) process utilizes selective magnetic microparticle composites to separate dissolved metals from solution. In this study, MACS particles were coated with neutral and acidic organophosphorus extractants,octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), and bis(2-ethyl-hexyl)phosphoric acid (D{sub 2}EHPA or HDEHP) and were evaluated for the separation of uranyl ions from nitric- and hydrochloric-acid solutions. The results suggest that a synergistic interaction between the particle surface and solvent coating may explain why the particles display, in some cases, orders of magnitude of higher partitioning coefficients than are estimated from solvent-extraction measurements. Particles coated with TBP and those coated with a combination of TOPO and D{sub 2}EHPA displayed the most desirable characteristics for removing uranium from dilute acid environments typical of contaminated groundwater. Uranium separation from moderate to highly acidic waste streams typical of Department of Energy (DOE) nuclear wastes is best accomplished using particles coated with a combination of CMPO and TBP.

Kaminski, M. D.; Nunez, L.; Chemical Engineering

2000-01-01

18

Selected uranium and uranium-thorium occurrences in New Hampshire  

USGS Publications Warehouse

Secondary uranium mineralization occurs in a northwest-trending fracture zone in the Devonian Concord Granite in recent rock cuts along Interstate Highway 89 near New London, New Hampshire. A detailed plane table map of this occurrence was prepared. Traverses using total gamma ray scintillometers throughout the pluton of Concord Granite identified two additional areas in which very small amounts of secondary mineralization occurs in the marginal zones of the body. All three areas lie along the same northwest trend. A ground radiometry survey of a large part of the Jurassic White Mountain batholith was conducted. Emphasis was placed on those areas from which earlier sampling by Butler (1975) had been done. No unusual geological characteristics were apparent around sample localities from which anomalous U and Th had been reported.. The results of this survey confirm previous conclusions that the red, coarse-grained, biotite granite phase of the Conway Granite is more radioactive than other phases of the Conway Granite or other rock types of the White Mountain Plutonic-Volcanic Series. Aplites associated with the Conway Granite were found .generally to be as radioactive as the red Conway Granite.

Bothner, W.A.

1978-01-01

19

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

20

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

21

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

22

Charge-Separation in Uranium Diazomethane Complexes Leading to C-H Activation and Chemical Transformation  

E-print Network

Charge-Separation in Uranium Diazomethane Complexes Leading to C-H Activation and Chemical of diphenyldiazomethane with [((t-Bu ArO)3tacn)UIII ] (1) results in an 2 -bound diphenyldiazomethane uranium complex-shell ligand, [((t-Bu ArO)3tacn)UIV (2 -NNCPh2)] (2). Treating Ph2CN2 with a uranium complex that contains

Meyer, Karsten

23

Process for separating ceramics of uranium and plutonium from zirconium by hydriding and mixtures thereof  

Microsoft Academic Search

A process is provided involving the use of hydrogen for the separation of uranium and plutonium and mixtures thereof, from composite substances and assemblies or mixtures containing metallic and ceramic components where the metallic component is zirconium or a zirconium alloy and the ceramic component contains uranium and\\/or plutonium.

B. Cech; E. Kaderabek; T. Hanslik

1977-01-01

24

Separation and solvent extraction of vanadium and uranium with n-propyl 2,3,4-trihydroxybenzoate.  

PubMed

A spectrophotometric method is described for the separation and determination of trace quantities of vanadium(IV) and (V) from uranium(VI). Vanadium is selectively separated from uranium by extraction at pH 6.5 into n-propyl 2,3,4-trihydroxybenzoate (PTB) dissolved in t-pentanol. Up to 120 microg of vanadium can be determined by measuring the absorbance of the blue complex in the organic phase at 585 nm. Uranium(VI) remains in the aqueous layer and can be determined spectrophotometrically by its reaction with PTB in aqueous acetone to produce a brown-red colour at pH 7.6-8.8. Solutions containing 25-275 microg of uranium absorb at 370-380 nm according to Beer's law. By modification, this procedure can be used for the determination of the two metals in native phosphate rocks. The effects of diverse ions on the determination of vanadium and uranium have also been examined. PMID:18960575

Jasim, F

1969-06-01

25

Laser isotope separation: Uranium. (Latest citations from the NTIS bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning the technology and assessment of laser separation of uranium isotopes, compounds, oxides, and alloys. Topics include uranium enrichment plants, isotope enriched materials, gaseous diffusion, centrifuge enrichment, reliability and safety, and atomic vapor separation. Citations also discuss commercial enrichment, market trends, licensing, international competition, and waste management. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1995-12-01

26

Separation of Uranium by an Extractant Encapsulated Magnetic Alginate Gels  

NASA Astrophysics Data System (ADS)

The aim of this work is to prepare environmentally friendly and practically applicable alginate magnetic biopolymers encapsulated tri-n-butyl phosphate (TBP) for the removal uranium ions. Some important process parameters such as initial pH, initial U(VI) concentration, adsorbent dosage, time, temperature and sorption isotherms for uranium uptake were studied and the thermodynamic parameters for U(VI) were determined.

Portakal, Z.; Gok, C.; Aytas, S.

27

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

28

Separation of uranium from technetium in recovery of spent nuclear fuel  

DOEpatents

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

Friedman, Horace A. (Oak Ridge, TN)

1985-01-01

29

Depleted uranium particles in selected Kosovo samples  

Microsoft Academic Search

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

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

2003-01-01

30

Separation of titanium and uranium from other elements by tannin  

Microsoft Academic Search

Titanium and uranium have been precipitated by tannin in the presence of various other ions, e.g., Fe3+, Al3+, Cr3+, Th4+, Zr4+, Bi3+, Pb2+, (VO)2+ and rare earths, which are kept in solution by EDTA. The precipitation was carried out by raising the pH of the acidic solution containing EDTA and tannin by dilute ammonium hydroxide or hexamine. The pH of

J. Das; S. Banerjee

1961-01-01

31

Anionexchange separation of uranium (VI) from thorium, zirconium, titanium, lanthanides and other elements in malonic and ascorbic acid media  

Microsoft Academic Search

The anion-exchange behaviour of uranium (VI) has been studied extensively in various mineral acid media [1], but similar studies with organic acid solutions are lacking. Although the negatively charged complex of uranium in acetic acid was studied [2, 3], very small amounts of uranium could be separated and phosphate interfered. Such studies were further extended to non-aqueous media [4]. The

M. Chakrovorty; S. M. Khopkar

1977-01-01

32

Ultratrace uranium fingerprinting with isotope selective laser ionization spectrometry.  

PubMed

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 for ultratrace measurement of the minor isotopes (234)U, (235)U, and (236)U with respect to (238)U. The inherent isotopic selectivity of three-step excitation with single-mode continuous wave lasers results in measurement of the minor isotopes at relative abundances below 1 ppm and is not limited by isobaric interferences such as (235)UH(+) during measurement of (236)U. This relative abundance limit is attained 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 microg 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. PMID:18613650

Ziegler, Summer L; Bushaw, Bruce A

2008-08-01

33

Separation of tc from Uranium and development of metallic Technetium waste forms  

NASA Astrophysics Data System (ADS)

The isotope Technetium-99 (99Tc) is a major fission product of the nuclear industry. In the last decade, approximately 20 tons of 99Tc have been produced by the US nuclear industry. Due to its long half-life (t1/2 = 214,000 yr), beta radiotoxicity, and high mobility as pertechnetate [TcO4]-, Tc represents long-term concern to the biosphere. Various options have been considered to manage 99Tc. One of them is its separation from spent fuel, conversion to the metal and incorporation into a metallic waste form for long-term disposal. After dissolution of spent fuel in nitric acid and extraction of U and Tc in organic media, previously developed methods can be used to separate Tc from U, convert the separate Tc stream to the metal and reuse the uranium component of the fuel. A variety of metallic waste forms, ranging from pure Tc metal to ternary Tc alloys combined with stainless steel (SS) and Zr are proposed. The goal of this work was to examine three major questions: What is the optimal method to separate Tc from U? After separation, what is the most efficient method to convert the Tc stream to Tc metal? Finally, what is the corrosion behavior of Tc metal, Tc-SS alloys and Tc-Zr-SS alloys in 0.01M NaCl? The goal is to predict the long term behavior of Tc metallic waste in a hypothetical storage environment. In this work, three methods have been used to separate Tc from U: anionic exchange resin, liquid-liquid extraction and precipitation. Of the three methods studied, anionic exchange resins is the most selective. After separation of Tc from U, three different methods were studied to convert the Tc stream to the metal: thermal treatment under hydrogen atmosphere, electrochemical and chemical reduction of pertechnetate in aqueous media. The thermal treatment of the Tc stream under hydrogen atmosphere is the preferred method to produce Tc metal. After Tc metal is isolated, it will be incorporated into a metal host phase. Three different waste forms were produced for corrosion studies in this work: Pure Tc metal, SS(Tc 2 wt%)Zr and SS(Tc 1.34 wt%) alloys. Corrosion rate measurements indicate that both SS(Tc 2 wt%)Zr and SS(Tc 1.34 wt%) alloys corrode more slowly than metallic Tc in the solutions tested.

Mausolf, Edward John

34

Separation and spectrophotometric determination of uranium(VI) by extraction with tri-n-octylphosphine oxide and benzophenone.  

PubMed

Uranium(VI) is separated by extraction from nitric acid medium into a molten mixture of tri-n-octylphosphine oxide and benzophenone at about 50 degrees . The organic phase solidifies on cooling and is separated and dissolved in ethanol. The uranium(VI) in this solution is then determined spectrophotometrically with 1-(2-pyridylazo)-2-naphthol. PMID:18962800

Shigetomi, Y; Kojima, T; Kamba, H

1980-12-01

35

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

36

Supercritical fluid extraction and separation of uranium from other actinides.  

PubMed

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

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

2014-06-15

37

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

38

Sample selection and testing of separation processes  

NASA Technical Reports Server (NTRS)

Phase partitioning, which has become an important tool for the separation and purification of biological materials, was studied. Instruments available for this technique were researched and a countercurrent distribution apparatus, the Biosheff MK2N, was purchased. Various proteins, polysaccharides and cells were studied as models to determine operating procedures and conditions for this piece of equipment. Results were compared with those obtained from other similar equipment, including a nonsynchronous coil planet centrifuge device. Additionally, work was done with affinity ligands attached to PEG, which can further enhance the separation capabilities of phase partitioning.

Karr, L. J.

1985-01-01

39

DISSOLUTION OF METAL OXIDES AND SEPARATION OF URANIUM FROM LANTHANIDES AND ACTINIDES IN SUPERCRITICAL CARBON DIOXIDE  

SciTech Connect

This paper investigates the feasibility of extracting and separating uranium from lanthanides and other actinides by using supercritical fluid carbon dioxide (sc-CO2) as a solvent modified with tri-n-butylphosphate (TBP) for the development of a counter current stripping technique, which would be a more efficient and environmentally benign technology for spent nuclear fuel reprocessing compared to traditional solvent extraction. Several actinides (U, Pu, and Np) and europium were extracted in sc-CO2 modified with TBP over a range of nitric acid concentrations and then the actinides were exposed to reducing and complexing agents to suppress their extractability. According to this study, uranium/europium and uranium/plutonium extraction and separation in sc-CO2 modified with TBP is successful at nitric acid concentrations of less than 6 M and at nitric acid concentrations of less than 3 M with acetohydroxamic acid or oxalic acid, respectively. A scheme for recycling uranium from spent nuclear fuel by using sc-CO2 and counter current stripping columns is presented.

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

2013-10-01

40

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

PubMed

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

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

2014-01-01

41

Dissolution of metal oxides and separation of uranium from lanthanides and actinides in supercritical carbon dioxide  

SciTech Connect

This paper investigates the feasibility of extracting and separating uranium from lanthanides and other actinides by using supercritical fluid carbon dioxide (sc-CO{sub 2}) as a solvent modified with tri-n-butylphosphate (TBP) for the development of a counter current stripping technique, which would be a more efficient and environmentally benign technology for spent nuclear fuel reprocessing compared to traditional solvent extraction. Several actinides (U, Pu, and Np) and europium were extracted in sc-CO{sub 2} modified with TBP over a range of nitric acid concentrations and then the actinides were exposed to reducing and complexing agents to suppress their extractability. According to this study, uranium/europium and uranium/plutonium extraction and separation in sc-CO{sub 2} modified with TBP is successful at nitric acid concentrations of less than 6 M and at nitric acid concentrations of less than 3 M with acetohydroxamic acid or oxalic acid, respectively. A scheme for recycling uranium from spent nuclear fuel by using sc-CO{sub 2} and counter current stripping columns is presented. (authors)

Quach, D.L.; Wai, C.M. [Department of Chemistry, University of Idaho, Moscow, Idaho 83844 (United States); Mincher, B.J. [Idaho National Lab, Idaho Falls, Idaho (United States)

2013-07-01

42

Studies on separation and purification of fission (99)Mo from neutron activated uranium aluminum alloy.  

PubMed

A new method has been developed for separation and purification of fission (99)Mo from neutron activated uranium-aluminum alloy. Alkali dissolution of the irradiated target (100mg) results in aluminum along with (99)Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)3, iodine as AgI/AgIO3 and molybdenum as Mo-?-benzoin oxime. Ruthenium is separated by volatilization as RuO4 and final purification of (99)Mo was carried out using anion exchange method. The radiochemical yield of fission (99)Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards. PMID:24657474

Rao, Ankita; Kumar Sharma, Abhishek; Kumar, Pradeep; Charyulu, M M; Tomar, B S; Ramakumar, K L

2014-07-01

43

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

44

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

45

Development of non-denaturing off-gel isoelectric focusing for the separation of uranium-protein complexes in fish.  

PubMed

An off-gel non-denaturing isoelectric focusing (IEF) method was developed to separate uranium-biomolecule complexes from biological samples as a first step in a multidimensional metalloproteomic approach. Analysis of a synthetic uranium-bovine serum albumin complex demonstrated the focusing ability of the liquid-phase IEF method and the preservation of most of the uranium-protein interactions. The developed method was applied to gill cytosol prepared from zebrafish (Danio rerio) exposed to depleted uranium. The results were compared in terms of resolution, recovery, and protein identities with those obtained by in-gel IEF using an immobilized pH gradient gel strip. PMID:24691723

Bucher, Guillaume; Frelon, Sandrine; Simon, Olivier; Lobinski, Ryszard; Mounicou, Sandra

2014-05-01

46

Methods for selective functionalization and separation of carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

47

Extraction of uranium from soil using selective chelators with secondary concentration using water soluble polymers  

SciTech Connect

Studies have investigated the extraction and recovery of uranium from contaminated soil containing both sorbed and metallic uranium. Our goal was to selectively bind and recover uranium from this soil and minimize secondary waste generation. Our approach was to determine optimal chelators for uranium extraction using contaminated soil taken from an area at LANL where open air testing of explosives containing depleted uranium was conducted. Uranium concentrations range in the soil from 1000-5000ppm. We have found that equimolar carbonate/bicarbonate solution in conjunction with an oxidant, sodium hypochlorite, is an excellent extractant for uranium from this soil, removing 90+% of the uranium. Our present focus is on the recovery and concentration of uranium from the extractant solution using a large water soluble polymer (>10,000 MW) as a secondary chelator for complexing the extracted uranium:carbonate complex. Using ultrafiltration, the volume of waste can be reduced 100+ fold. These commercially available polymers can then be regenerated and re-used. Using this approach, we are able to recover 90+% of the uranium in a minimal volume.

Duran, B.L.; Ehler, D.S.; Sauer, N.N. [Los Alamos National Lab., NM (United States)

1997-12-31

48

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

E-print Network

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

Kamal, Altamash

1982-01-01

49

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

2009-11-15

50

Development of a Selective Calixarene Sensor for Uranium  

SciTech Connect

Traditionally, measurements of uranium in wastewater have been obtained by laboratory based instrumentation, such as inductively coupled plasma spectroscopy, ion-chromatography and radiochemical methods. However, such methods and equipment, whilst offering excellent sensitivity and reproducibility, are far too large and heavy to be portable. Therefore, there has been a lot of interest in developing a portable sensor to carry out uranium measurements. This work describes how a class of molecule called calixarenes have been used to develop a sensing methodology for measuring uranium concentration at low levels. This has been achieved by taking the established coordinating properties of the calixarene molecule for uranium and then adding functionalities to the molecule to make it adhere to metal surfaces. This way, a layer of the uranophilic molecule has been prepared on electrode surfaces, one molecule thick. These electrodes have been shown to be sensitive to uranium between 5 and 300 parts per billion. Using these modified electrodes, a portable device has been developed, which potentially allows for measurement of uranium in the field. This sensor therefore presents a very significant advantage in that it allows for rapid determination of low levels of uranium in wastewater, whilst offering portability.

Evans-Thompson, C.; Field, S. E.; Jones, A. H.; Kan, M. J.; Hall, C. W.; Nicholson, G. P.

2002-02-26

51

Preconcentration and Separation of Uranium from Thorium by Solid Phase Extraction with XAD?4 Modified with Organic Reagents  

Microsoft Academic Search

Uranyl ion can be separated from aqueous solution and preconcentrated on XAD?4 modified with organic reagents. Dibenzoyl methane (DBM), 8?hydroxy quinoline (oxine), and tri?n?octyl phosphine oxide (TOPO) were impregnated on the adsorber resin and treated with aqueous solutions containing microgram quantity of uranium. The preconcentrated uranium could be eluted out with dilute acid from the column modified with DBM or

K. Venkatesh; B. Maiti

2005-01-01

52

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

SciTech Connect

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

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

1991-01-01

53

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

54

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

55

New data on separation and position angle of selected binaries  

NASA Astrophysics Data System (ADS)

We report on a sample of the data aquired on may 2012 at the 31 inch NURO telescope at Anderson Mesa near Flagstaff, Arizona pertaining the separation and position angle of selected binary stars. A CCD camera coupled to the NURO telescope allows for a simple and straightforward procedure for obtaining the images of the binaries. Analysis of the images is straigthforward and both direct and software methodology yield the separation and position angle of the binary stars. The data obtained is suitable for insertion in the Washington Double Star Catalog of the US Naval Observatory.

Muller, Rafael J.; Lopez, Andy J.; Torres, Brian S.; Mendoza, Lizyan; Vergara, Nelson; Cersosimo, Juan; Martinez, Luis

2015-01-01

56

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

57

Use of Zirconium(IV) Arsenophosphate Columns for Cation Exchange Separation of Metal Ions Interfering in the Spectrophotometric Determination of Uranium with Sodium Diethyl Dithiocarbamate  

Microsoft Academic Search

A simple cation exchange method has been developed for the quantitative separation of uranium from some metal ions which generally interfere in its spectrophotometric determination using sodium diethyl dithiocarbamate as a reagent. The method requires only a single bed operation and enables a satisfactory (Error 5%) separation of uranium [UO2(II)] upto 1080 ?g from ten metal ions on a 2

K. G. Varshney; Sanjay Agrawal; Kanak Varshney; S. Anwar

1985-01-01

58

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

59

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

60

SEPARATION OF CADMIUM FROM URANIUM, COBALT, NICKEL, MANGANESE, ZINC, COPPER, TITANIUM, AND OTHER ELEMENTS BY CATION EXCHANGE CHROMATOGRAPHY  

Microsoft Academic Search

A study of the distribution curves of cations with AG 5OW-X8 resin in ; hydrochloric acid showed that most cations are adsorbed strongly from 0.5 N ; hydrochloric acid, while cadmium is not. This fact was used to develop a cation ; exchange chromatographic procedure to separate cadmium from uranium, cobalt, ; nickel, manganese, zinc, copper, and titanium. Other cations

F. W. E. Strelow; F. W. E

1960-01-01

61

Simultaneous spectrophotometric determination of uranium and thorium by flow injection analysis using selective masking.  

PubMed

A flow injection system for the simultaneous determination of uranium and thorium has been developed by using selective masking and a spectrophotometric detector with two flow cells aligned with the same optical path. The injected sample solution was first mixed with a reagent solution containing Chromazurol S (CAS) and cetyltrimethylammonium chloride (CTMAC), and the total absorbance of uranium- and thorium-CAS complexes was measured in the first flow cell at 620 nm. The sample stream was then mixed with an EDTA solution in order to convert the thorium-CAS complex to a thorium-EDTA complex, and the absorbance of the uranium-CAS complex was measured in the second flow cell. The detection limits were 10 microg dm(-3) for uranium and 7 microg dm(-3) for thorium. The calibration graphs were linear (r < 0.9998) at least over the ranges of 0.1 to 10 mg dm(-3) for uranium and 0.08 to 8 mg dm(-3) for thorium. The RSDs were less than 1.5% (n = 3) in the calibration range. Uranium and thorium of up to the 6-fold concentration to each other could be determined in admixtures with relative errors of less than 3.3%. The sample throughput was 24 per hour. The proposed system was successfully applied to the analysis of a uranium-thorium ore mock solution by coupling with anion-exchange in a magnesium nitrate medium to eliminate interference from coexisting elements. PMID:12608764

Hirano, Yoshihiro; Ogawa, Yuichi; Oguma, Koichi

2003-02-01

62

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

PubMed

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

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

2012-11-01

63

(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

64

Feature selection with redundancy-constrained class separability.  

PubMed

Scatter-matrix-based class separability is a simple and efficient feature selection criterion in the literature. However, the conventional trace-based formulation does not take feature redundancy into account and is prone to selecting a set of discriminative but mutually redundant features. In this brief, we first theoretically prove that in the context of this trace-based criterion the existence of sufficiently correlated features can always prevent selecting the optimal feature set. Then, on top of this criterion, we propose the redundancy-constrained feature selection (RCFS). To ensure the algorithm's efficiency and scalability, we study the characteristic of the constraints with which the resulted constrained 0-1 optimization can be efficiently and globally solved. By using the totally unimodular (TUM) concept in integer programming, a necessary condition for such constraints is derived. This condition reveals an interesting special case in which qualified redundancy constraints can be conveniently generated via a clustering of features. We study this special case and develop an efficient feature selection approach based on Dinkelbach's algorithm. Experiments on benchmark data sets demonstrate the superior performance of our approach to those without redundancy constraints. PMID:20227975

Zhou, Luping; Wang, Lei; Shen, Chunhua

2010-05-01

65

Separation and determination of thorium, uranium and mixed rare-earth elements as their UV/Vis absorbing complexes by capillary zone electrophoresis.  

PubMed

Separation and determination of thorium, uranium and mixed rare-earth elements (RE) as their 2-(2-arsenophenylazo)-1,8-dihydroxyl-7-(4-chloro-2,6-dibromophenylazo)-naphthalene-3,6-disulfonic acid (DBC-As) complexes by capillary electrophoresis is presented in this paper. The pre-column derivitization conditions are discussed. Some separation parameters such as pH value, type of carrier electrolyte, applied voltage, the concentration of ligand in buffer and the sample size are also optimized. Under the selected conditions, the complete separation of thorium and uranium from mixed RE was accomplished in 10 min. Quantitative analyses exhibited an excellent linear dynamic relationship in the range of over two orders of magnitude. Detection limits of 4.81x10(-8), 7.23x10(-8), and 59.4x10(-8) mol l(-1) for RE, Th and U were obtained, respectively. This method was applied to the determination of these metal ions in ore samples. PMID:18967328

Liu, B F; Liu, L B; Cheng, J K

1998-10-01

66

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

67

Feature Subset Selection, Class Separability, and Genetic Algorithms  

SciTech Connect

The performance of classification algorithms in machine learning is affected by the features used to describe the labeled examples presented to the inducers. Therefore, the problem of feature subset selection has received considerable attention. Genetic approaches to this problem usually follow the wrapper approach: treat the inducer as a black box that is used to evaluate candidate feature subsets. The evaluations might take a considerable time and the traditional approach might be unpractical for large data sets. This paper describes a hybrid of a simple genetic algorithm and a method based on class separability applied to the selection of feature subsets for classification problems. The proposed hybrid was compared against each of its components and two other feature selection wrappers that are used widely. The objective of this paper is to determine if the proposed hybrid presents advantages over the other methods in terms of accuracy or speed in this problem. The experiments used a Naive Bayes classifier and public-domain and artificial data sets. The experiments suggest that the hybrid usually finds compact feature subsets that give the most accurate results, while beating the execution time of the other wrappers.

Cantu-Paz, E

2004-01-21

68

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

Microsoft Academic Search

A microchemical procedure was developed for the separation and isotopic analysis of U and Th from irradiated (Th,U)Oâ 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 HNOâ solution. The bead sorbed approximately 1.7 ..mu..g of U and 4.8..mu..g of Th

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

1983-01-01

69

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

SciTech Connect

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

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

1985-01-01

70

Electrochemical separation of uranium in the molten system LiF-NaF-KF-UF4  

NASA Astrophysics Data System (ADS)

This article is focused on the electrochemical investigation (cyclic voltammetry and related studies) of possible reduction of U4+ ions to metal uranium in the molten system LiF-NaF-KF(eut.)-UF4 that can provide basis for the electrochemical extraction of uranium from molten salts. Two-step reduction mechanism for U4+ ions involving one electron exchange in soluble/soluble U4+/U3+ system and three electrons exchange in the second step were found on the nickel working electrode. Both steps were found to be reversible and diffusion controlled. Based on cyclic voltammetry, the diffusion coefficients of uranium ions at 530 °C were found to be D(U4+) = 1.64 × 10-5 cm2 s-1 and D(U3+) 1.76 × 10-5 cm2 s-1. Usage of the nickel spiral electrode for electrorefining of uranium showed fairly good feasibility of its extraction. However some oxidant present during the process of electrorefining caused that the solid deposits contained different uranium species such as UF3, UO2 and K3UO2F5.

Korenko, M.; Straka, M.; Szatmáry, L.; Ambrová, M.; Uhlí?, J.

2013-09-01

71

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

72

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

73

Molecular dynamics simulation of nanoporous graphene for selective gas separation  

E-print Network

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

Au, Harold (Harold S.)

2012-01-01

74

Selected Hanford reactor and separations operating data for 1960--1964  

SciTech Connect

The purpose of this letter report is to reconstruct from available information that data which can be used to develop daily reactor operating history for 1960--1964. The information needed for source team calculations (as determined by the Source Terms Task Leader) were extracted and included in this report. The data on the amount of uranium dissolved by the separations plants (expressed both as tons and as MW) is also included in this compilation.

Gydesen, S.P.

1992-09-01

75

Selected Hanford reactor and separations operating data for 1960--1964. Hanford Environmental Dose Reconstruction Project  

SciTech Connect

The purpose of this letter report is to reconstruct from available information that data which can be used to develop daily reactor operating history for 1960--1964. The information needed for source team calculations (as determined by the Source Terms Task Leader) were extracted and included in this report. The data on the amount of uranium dissolved by the separations plants (expressed both as tons and as MW) is also included in this compilation.

Gydesen, S.P.

1992-09-01

76

Helicity Selective Separation of Zeolite-supported Single-walled Carbon Nanotubes Synthesized from  

E-print Network

1 Helicity Selective Separation of Zeolite-supported Single-walled Carbon Nanotubes Synthesized on metal supported Zeolite.10,11 Purification and helicity selective separation of SWNTs is still an important challenge. Two methods for purification, removal of metal catalysts and Zeolite, of SWNTs produced

Maruyama, Shigeo

77

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

PubMed

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

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

2014-10-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

79

Feature Subset Selection, Class Separability, and Genetic Algorithms  

Microsoft Academic Search

The performance of classiflcation algorithms in machine learn- ing is afiected by the features used to describe the labeled examples pre- sented to the inducers. Therefore, the problem of feature subset selection has received considerable attention. Genetic approaches to this problem usually follow the wrapper approach: treat the inducer as a black box that is used to evaluate candidate feature

Erick Cantú-paz

2004-01-01

80

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

81

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

SciTech Connect

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

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

1980-06-01

82

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

83

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

SciTech Connect

An analytical procedure was established in order to obtain selective fractions containing radium isotopes ({sup 228}Ra), thorium ({sup 232}Th), and rare earths from RETOTER (REsiduo de TOrio 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 {sup 228}Ra, {sup 226}Ra, {sup 238}U, {sup 210}Pb, and {sup 40}K concentrations in the selective fractions and total residue determined by high-resolution gamma spectroscopy, considering radioactive equilibrium of the samples.

Alves de Freitas, Antonio; Abrao, Alcidio [Centro de Quimica e do Meio Ambiente (Brazil); Godoy dos Santos, Adir Janete; Pecequilo, Brigitte Roxana Soreanu [Centro de Metrologia das Radiacoes Instituto de Pesquisas Energeticas e Nucleares Av. Prof. Lineu Prestes, 2242-Cidade Universitaria-Zip Code 05508-000 Sao Paulo-SP (Brazil)

2008-08-07

84

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; Abrão, Alcídio

2008-08-01

85

Synthesis of a novel chelating resin for the separation and preconcentration of uranium(VI) and its spectrophotometric determination.  

PubMed

A novel chelating polymer including three different functional groups, such as amidoxime (-C(NH(2))=NOH), azo (-N=N-) and carboxylic acid (-COOH), was synthesized. The poly(acrylamidoxime-co-(1-(2-pirydylazo)-2-naphtyl-2-methacrylate)-co-methacrylicacid) (APM) polymer, prepared in three steps, was characterized by FT-IR and elemental analyses. The resin was used for solid-phase extractive separation and the preconcentration of trace amounts of uranium(VI). The determination of U(VI) was performed by a spectrophotometric method using Arsenazo III as a complexing agent. The optimum conditions were found for the quantitative recovery of U(VI) (pH 5; eluent, 3 mol L(-1) HClO(4); sample and eluent flow rates, 1 mL min(-1) etc.). The capacity of the APM resin for U(VI) was found to be 24.2 mg g(-1). A preconcentration factor of 37.5 and the three sigma detection limit of 1.6 microg L(-1) (n = 20) were achieved for U(VI) ions. The polymer was used for separating and preconcentrating the uranyl ion existing in seawater samples and a certified reference material (TMDA 70; fortified lake water sample). PMID:19359797

Hazer, Orhan; Kartal, Senol

2009-04-01

86

Oil/Water separation with selective superantiwetting/superwetting surface materials.  

PubMed

The separation of oil from oily water is an important pursuit because of increasing worldwide oil pollution. Separation by the use of materials with selective oil/water absorption is a relatively recent area of development, yet highly promising. Owing to their selective superantiwetting/superwetting properties towards water and oil, superhydrophobic/superoleophilic surfaces and underwater superoleophobic surfaces have been developed for the separation of oil/water-free mixtures and emulsions. In this Review, after a short introduction to oil/water separation, we describe the principles of materials with selective oil/water absorption and outline recent advances in oil/water separation with superwetting/superantiwetting materials, including their design, their fabrication, and models of experimental setups. Finally, we discuss the current state of this new field and point out the remaining problems and future challenges. PMID:25425089

Chu, Zonglin; Feng, Yujun; Seeger, Stefan

2015-02-16

87

Computer program for spacecraft-booster separation spring selection, set composition, and location determination  

NASA Technical Reports Server (NTRS)

Program combines all calculation and determination requirements into one comprehensible technique. Program automatically performs selection of separation springs, composition of spring sets, and correct spring location with improved accuracy and reliability.

1974-01-01

88

Uranium enrichment by the separation nozzle method within the framework of German\\/Brazilian cooperation  

Microsoft Academic Search

In the separation nozzle process, the enrichment of ²³⁵U is achieved by extremely high centrifugal forces in a curved flow of UFâ diluted by a light gas. Remarkable progress has been made in the economy of the process by bringing up the gas pressure and by introducing a nozzle system with double deflection of the jet. While the specific energy

E. W. Becker; P. Nogueira Batista; H. Voelcker

1981-01-01

89

Separation of thorium and uranium from silicate rock samples using two commercial extraction chromatographic resins.  

PubMed

A new chemical separation technique to isolate Th and U from silicate rocks was established by using two kinds of commercial extraction chromatographic resins. In the first column procedure, with U/TEVA·spec resin, almost all elements except Th and U were eluted by 4 M HNO(3). Th was then separated by using 5 M HCl, and U was finally isolated by successive addition of 0.1 M HNO(3). A significant amount of Zr still remained in the Th fraction, which was then further purified in the second column stage using TEVA·spec resin. In the second procedure, Zr was eluted first by using 2 M HNO(3), and then Th was collected by 0.1 M HNO(3). Both the Th and U fractions obtained by these procedures were sufficiently pure for thermal ionization mass spectrometric (TIMS) analysis. Recovery yields of Th and U exceeded 90%, and total blanks were <19 pg for Th and <10 pg for U. Our method has advantages over previous methods in terms of matrix effects, tailing problems, and degree of isolation. Since Th and U are effectively separated without suffering any matrix interference from coexisting cations and anions, this technique can be used not only for the analysis of igneous rock samples but also for the analysis of soils, marine sediments, carbonates, phosphates and seawater, groundwater, and surface water. PMID:21662935

Yokoyama, T; Makishima, A; Nakamura, E

1999-01-01

90

Selective aqueous extraction of organics coupled with trapping by membrane separation  

SciTech Connect

This patent describes improvement in an organic/aqueous extraction process for the extraction of an organic solute from an organic solvent or solvent mixture with an aqueous-based extractant. The improvement comprises continuously recycling the aqueous-based extractant through a membrane separation process that selectively removes the organic solute from the aqueous-based extractant, the membrane separation process being selected from at least one of reverse osmosis, nanofiltration, ultrafiltration, membrane distillation, pervaporation, membrane contactor and supported-liquid membrane.

van Eikeren, P.; Brose, D.J.; Ray, R.J.

1991-08-20

91

Loading Capacities for Uranium, Plutonium and Neptunium in High Caustic Nuclear Waste Storage Tanks Containing Selected Sorbents  

Microsoft Academic Search

In this study the loading capacities of selected actinides onto some of the most common sorbent materials which are present in caustic nuclear waste storage tanks have been determined. Some of these transition metal oxides and activated carbons easily absorb or precipitate plutonium, neptunium and even uranium, which if care is not taken may lead to unwanted accumulation of some

2004-01-01

92

Separation between reference surfaces of selected vertical datums  

NASA Astrophysics Data System (ADS)

This paper discusses the separation between the reference surface of several vertical datums and the geoid. The data used includes a set of Doppler positioned stations, transformation parameters to convert the Doppler positions to ITRF90, and a potential coefficient model composed of the JGM-2 (NASA model) from degree 2 to 70 plus the OSU91A model from degree 71 to 360. The basic method of analysis is the comparison of a geometric geoid undulation derived from an ellipsoidal height and an orthometric height with the undulation computed from the potential coefficient model The mean difference can imply a bias of the datum reference surface with respect to the geoid. Vertical datums in the following countries were considered: England, Germany, United States, and Australia. The following numbers represent the bias values of each datum after adopting an equatorial radius of 6378136.3m: England (-87 cm), Germany (4 cm), United States (NGVD29 (-26 cm)), NAVD88 (-72 cm), Australia AHD (mainland, -68 cm); AHD (Tasmania, -98 cm). A negative sign indicates the datum reference surface is below the geoid. The 91 cm difference between the datums in England and Germany has been independently estimated as 80 cm. The 30 cm difference between AHD (mainland) and AHD (Tasmania) has been independently estimated as 40 cm. These bias values have been estimated from data where the geometric/ gravimetric geoid undulation difference standard deviation, at one station, is typically ±100 cm, although the mean difference is determined more accurately. The results of this paper can be improved and expanded with more accurate geocentric station positions, more accurate and consistent heights with respect to the local vertical datum, and a more accurate gravity field for the Earth. The ideas developed here provide insight on the determination of a world height system.

Rapp, Richard H.

1994-03-01

93

ULTRAVIOLET SPECTROPHOTOMETRIC DETERMINATION OF URANIUM. Separation of Uranium from Bismuth Using Tris(2-ethylhexyl)phosphine Oxide. Work completed, May 1958  

Microsoft Academic Search

An ultraviolet spectrophotometric method for the determination of ; uranium was developed which is based on the ultraviolet absorption of the complex ; of uranium(VI) with tris-(2-ethylhexyl)phosphine oxide (TEHPO). The complex is ; formed by extracting unanium(VI) from an aqueous 6M sodium nitrate solution in ; the pH range 2.5to 3.0 into 0.1M solution of TEHPO in an inert diluent,

A. H. A. Heyn; G. Banerjee

1959-01-01

94

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

PubMed

Two former uranium mines and a uranium reprocessing factory in the city of Aktau, Kazakhstan, may represent a risk of contaminating the surrounding areas by uranium and its daughter elements. One of the possible fingerprinting tools for studying the environmental contamination is using plant samples, collected in the surroundings of this city in 2007 and 2008. The distribution pattern of environmental pollution by uranium and thorium was evaluated by determining the thorium and uranium concentrations in plant samples (Artemisia austriaca) from the city of Aktau and comparing these results with those obtained for the same species of plants from an unpolluted area (town of Kurchatov). The determination of the uranium and thorium concentrations in different parts of A. austriaca plants collected from the analyzed areas demonstrated that the main contamination of the flora in areas surrounding the city of Aktau was due to dust transported by the wind from the uranium mines. The results obtained demonstrate that all the areas surrounding Aktau have a higher pollution level due to thorium and uranium than the control area (Kurchatov). A few "hot points" with high concentrations of uranium and thorium were found near the uranium reprocessing factory and the uranium mines. PMID:20346550

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

2010-05-01

95

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

PubMed

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

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

2014-01-01

96

A simple-rapid method to separate uranium, thorium, and protactinium for U-series age-dating of materials.  

PubMed

Uranium-series dating techniques require the isolation of radionuclides in high yields and in fractions free of impurities. Within this context, we describe a novel-rapid method for the separation and purification of U, Th, and Pa. The method takes advantage of differences in the chemistry of U, Th, and Pa, utilizing a commercially-available extraction chromatographic resin (TEVA) and standard reagents. The elution behavior of U, Th, and Pa were optimized using liquid scintillation counting techniques and fractional purity was evaluated by alpha-spectrometry. The overall method was further assessed by isotope dilution alpha-spectrometry for the preliminary age determination of an ancient carbonate sample obtained from the Lake Bonneville site in western Utah (United States). Preliminary evaluations of the method produced elemental purity of greater than 99.99% and radiochemical recoveries exceeding 90% for U and Th and 85% for Pa. Excellent purity and yields (76% for U, 96% for Th and 55% for Pa) were also obtained for the analysis of the carbonate samples and the preliminary Pa and Th ages of about 39,000 years before present are consistent with (14)C-derived age of the material. PMID:24681438

Knight, Andrew W; Eitrheim, Eric S; Nelson, Andrew W; Nelson, Steven; Schultz, Michael K

2014-08-01

97

State-selective x-ray studies of radiative recombination into bare and H-like uranium at threshold energies  

NASA Astrophysics Data System (ADS)

A state-selective investigation of radiative recombination (RR) at threshold energies has been performed by x-ray detection at the electron cooler of the experimental storage ring (ESR) at Gesellschaft für Schwerionenforschung (GSI) for decelerated bare and hydrogenlike uranium ions. The application of the deceleration mode enabled us to observe state-selective RR into the K and L shells of bare and H-like uranium. The observed relative RR intensities into these low-lying bound states exhibit a good agreement with rigorous relativistic predictions, whereas the nonrelativistic approach fails to reproduce the data. Furthermore, the scaled relativistic one-electron treatment seems to be insufficient for the state-selective description of RR into H-like species at extremely low energies, suggesting the importance of electron-electron interactions for the RR process at the threshold.

Reuschl, R.; Gumberidze, A.; Kozhuharov, C.; Spillmann, U.; Tashenov, S.; Stöhlker, Th.; Eichler, J.

2008-03-01

98

[Determination of 235U/238U isotope ratios in camphor tree bark samples by MC-ICP-MS after separation of uranium from matrix elements].  

PubMed

Twelve camphor (cinnamomum camphora) tree bark samples were collected from Hiroshima and Kyoto, and the matrix element composition and morphology of the outer surface of these camphor tree bark samples were studied by EDXS and SEM respectively. After a dry decomposition, DOWEX 1-X8 anion exchange resin was used to separate uranium from matrix elements in these camphor tree bark samples. Finally, 235U/238 U isotope ratios in purified uranium solutions were determined by MC-ICP-MS. It was demonstrated that the outer surface of these camphor tree bark samples is porous and rough, with Al, Ca, Fe, K, Mg, Si, C, O and S as its matrix element composition. Uranium in these camphor tree bark samples can be efficiently separated and quantitatively recovered from the matrix element composition. Compared with those collected from Kyoto, the camphor tree bark samples collected from Hiroshima have significantly higher uranium contents, which may be due to the increased aerosol mass concentration during the city reconstruction. Moreover, the 235 U/23.U isotope ratios in a few camphor tree bark samples collected from Hiroshima are slightly higher than 0.007 25. PMID:17944430

Wang, Xiao-Ping; Zhang, Ji-Long

2007-07-01

99

Microscale phase separator for selective extraction of CO2 from methanol solution flow  

NASA Astrophysics Data System (ADS)

This study is aimed at understanding the limits in reducing the size of a membrane-based CO2 separator and its pressure head needs and energy consumption, while maximizing its selectivity. The separator consists of a flow channel capped by a hydrophobic nanoporous membrane through which CO2 exits the anode flow stream of a direct methanol fuel cell (DMFC). A systematic study is conducted to determine the effect of differential pressure across the membrane, flow velocity, and flow channel dimensions on the separation process. The extraction flux was found to change linearly with pressure difference across the membrane. The effect of flow velocity on the extraction flux was negligible up to a critical velocity beyond which the separation process ceased. The separation selectivity enhanced by increasing the differential pressure across the membrane but did not change with varying the flow velocity and channel depth. Using the findings of the first part of the study, an optimal micro-separator (with a footprint of approximately 10 × 1 mm2) was designed/fabricated for a 20 W DMFC and its performance was experimentally analyzed. An unprecedented separation selectivity of close to 200 was achieved at a differential pressure of about 10 kPa and negligible energy consumption.

Fazeli, Abdolreza; Moghaddam, Saeed

2014-12-01

100

Geological and geochemical aspects of uranium deposits: a selected, annotated bibliography. [474 references  

SciTech Connect

This bibliography, a compilation of 474 references, is the fourth in a series compiled from the National Uranium Resource Evaluation (NURE) Bibliographic Data Base. This data base was created for the Grand Junction Office of the Department of Energy's National Uranium Resource Evaluation Project by the Ecological Sciences Information Center, Oak Ridge National Laboratory. The references in the bibliography are arranged by subject category: (1) geochemistry, (2) exploration, (3) mineralogy, (4) genesis of deposits, (5) geology of deposits, (6) uranium industry, (7) geology of potential uranium-bearing areas, and (8) reserves and resources. The references are indexed by author, geographic location, quadrangle name, geoformational feature, and keyword.

Thomas, J.M.; Garland, P.A.; White, M.B.; Daniel, E.W.

1980-09-01

101

Determination of Uranium Metal Concentration in Irradiated Fuel Storage Basin Sludge Using Selective Dissolution  

SciTech Connect

Uranium metal corroding in water-saturated sludges now held in the US Department of Energy Hanford Site K West irradiated fuel storage basin can create hazardous hydrogen atmospheres during handling, immobilization, or subsequent transport and storage. Knowledge of uranium metal concentration in sludge thus is essential to safe sludge management and process design, requiring an expeditious routine analytical method to detect uranium metal concentrations as low as 0.03 wt% in sludge even in the presence of 30 wt% or higher total uranium concentrations.

Delegard, Calvin H.; Sinkov, Sergey I.; Chenault, Jeffrey W.; Schmidt, Andrew J.; Welsh, Terri L.; Pool, Karl N.

2014-03-01

102

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

103

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

104

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

105

Selective separation of Eu{sup 3+} using polymer-enhanced ultrafiltration  

SciTech Connect

A process to selectively remove {sup 241}Am from liquid radioactive waste was investigated as an actinide separation method applicable to Hanford and other waste sites. The experimental procedures involved removal of Eu, a nonradioactive surrogate for Am, from aqueous solutions at pH 5 using organic polymers in conjunction with ultrafiltration. Commercially available polyacrylic acid (60,000 MW) and Pacific Northwest Laboratory`s (PNL) synthesized E3 copolymer ({approximately}10,000 MW) were tested. Test solutions containing 10 {mu}g/mL of Eu were dosed vath each polymer at various concentrations in order to bind Eu (i.e., by complexation and/or cation exchange) for subsequent rejection by an ultrafiltration coupon. Test solutions were filtered with and without polymer to determine if enhanced Eu separation could be achieved from polymer treatment. Both polymers significantly increased Eu removal. Optimum concentrations were 20 {mu}g/mL of polyacrylic acid and 100 {mu}g/mL of E3 for 100% Eu rejection by the Amicon PM10 membrane at 55 psi. In addition to enhancement of removal, the polymers selectively bound Eu over Na, suggesting that selective separation of Eu was possible. This suggests that polymer-enhanced ultrafiltration is a potential process for separation of {sup 241}Am from Hanford tank waste, further investigation of binding agents and membranes effective under very alkaline and high ionic strength is warranted. This process also has potential applications for selective separation of toxic metals from industrial process streams.

Norton, M.V.

1994-03-01

106

Method for converting uranium oxides to uranium metal  

DOEpatents

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

Duerksen, Walter K. (Norris, TN)

1988-01-01

107

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. PMID:20699706

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

2010-01-01

108

Precursor Selection and Process Conditions in the Preparation of Carbon Membrane for Gas Separation: A Review  

Microsoft Academic Search

Carbon membranes prepared by pyrolysis\\/carbonization of polymeric precursors have been studied in the last few years as a promising candidate for gas separation process. As the aim of this paper, a review on polymer precursor selection and effect of pyrolysis conditions on carbon membrane characteristics and performances were discussed in detail. A number of different polymer precursors have been surveyed

W. N. W. Salleh; A. F. Ismail; T. Matsuura; M. S. Abdullah

2011-01-01

109

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

110

A robust and conductive metal-impregnated graphene oxide membrane selectively separating organic vapors.  

PubMed

A small amount of Zn impregnated by ALD triggered enhancement of the mechanical as well as electrical properties of the graphene oxide (GO) membrane. In addition, the Zn-impregnated membranes selectively separated diverse organic vapors while maintaining high water permeability. PMID:25572131

Lam, Do Van; Gong, Tao; Won, Sejeong; Kim, Jae-Hyun; Lee, Hak-Joo; Lee, Changgu; Lee, Seung-Mo

2015-01-29

111

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

112

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

SciTech Connect

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

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

1991-09-01

113

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

SciTech Connect

Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective 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

114

Selective separation of similarly sized proteins with tunable nanoporous block copolymer membranes.  

PubMed

An integral asymmetric membrane was fabricated in a fast and one-step process by combining the self-assembly of an amphiphilic block copolymer (PS-b-P4VP) with nonsolvent-induced phase separation. The structure was found to be composed of a thin layer of densely packed highly ordered cylindrical channels with uniform pore sizes perpendicular to the surface on top of a nonordered sponge-like layer. The as-assembled membrane obtained a water flux of more than 3200 L m(-2) h(-1) bar(-1), which was at least an order of magnitude higher than the water fluxes of commercially available membranes with comparable pore sizes, making this membrane particularly well suited to size-selective and charge-based separation of biomolecules. To test the performance of the membrane, we conducted diffusion experiments at the physiological pH of 7.4 using bovine serum albumin (BSA) and globulin-?, two proteins with different diameters but too close in size (2-fold difference in molecular mass) to be efficiently separated via conventional dialysis membrane processes. The diffusion rate differed by a factor of 87, the highest value reported to date. We also analyzed charge-based diffusive transport and separation of two proteins of similar molecular weight (BSA and bovine hemoglobin (BHb)) through the membrane as a function of external pH. The membrane achieved a selectivity of about 10 at pH 4.7, the isoelectric point (pI) of BSA. We then positively charged the membrane to improve the separation selectivity. With the modified membrane BSA was completely blocked when the pH was 7.0, the pI of BHb, while BHb was completely blocked at pH 4.7. Our results demonstrate the potential of our asymmetric membrane to efficiently separate biological substances/pharmaceuticals in bioscience, biotechnology, and biomedicine applications. PMID:23252799

Qiu, Xiaoyan; Yu, Haizhou; Karunakaran, Madhavan; Pradeep, Neelakanda; Nunes, Suzana P; Peinemann, Klaus-Viktor

2013-01-22

115

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

116

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

NASA Technical Reports Server (NTRS)

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

Vasquez, Arturo; Bradley, Karla F.

2010-01-01

117

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

NASA Astrophysics Data System (ADS)

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

Wang, Lei

118

Selective foam separation of binary protein solution by SDS complexation method.  

PubMed

A fundamental study about the selective foam separation of protein mixture was carried out. A solution containing two proteins, ovalbumin (OA) and lysozyme (LZ), and an anionic surfactant, sodium dodecyl sulfate (SDS), was adjusted to pH 6.0, which referred to an intermediate state between the isoelectric points of the proteins. The solution was processed by continuous foam separation. The results showed that a proper addition of SDS greatly improved the selective recovery of LZ to OA. The experimental data were well explained by a simple model that most of cationic protein molecules (LZ) are associated with SDS and the adsorption of all the species including LZ-SDS complexes are subjected to Langmuir adsorption isotherm. The results also showed that one of the Langmuir parameters, which means a kind of lyophillic property of adsorbed material, of LZ-SDS complexes was extremely large as compared with that of primary protein. PMID:16290871

Suzuki, Akira; Yasuhara, Kazuki; Seki, Hideshi; Maruyama, Hideo

2002-09-15

119

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

PubMed

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

Lehmann, U

1985-01-01

120

Selective Separation and Preconcentration of Total Tin Using Quercetin as Chelating Agent  

Microsoft Academic Search

Three methods were developed for rapid and selective extraction of total tin as Sn(IV) using quercetin (H5Q) as chelating agent, prior to its determination by hydride generation atomic absorption spectrometry (HGAAS). H5Q was chemically or physically immobilized onto silica gel or polyurethane foam, respectively, and used for the separation of Sn(IV) by the solid phase extraction (SPE) technique. The SPE

Mohamed M. Hassanien; Ibrahim M. M. Kenawy

2007-01-01

121

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

122

Separation of fatty acid methyl esters from tall oil by selective adsorption  

Microsoft Academic Search

Fatty acid methyl esters (FAME) and resin acids (RA) were separated from tall oil by selective adsorption. Commercial nonmodified\\u000a molecular sieve 13X was used as adsorbent. The adsorption isotherms of fatty acids (FA), FAME, and RA on molecular sieve 13X\\u000a at 25°C were determined using various solvents. The solvents were methanol, ethanol, isopropanol, acetone, benzene, hexane,\\u000a isooctane, petroleum ether (40–60°C),

Güldem Üstün

1996-01-01

123

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

124

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

125

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

PubMed

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

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

2009-06-01

126

Radioecological survey at selected sites hit by depleted uranium ammunitions during the 1999 Kosovo conflict  

Microsoft Academic Search

A field study, organised, coordinated and conducted under the responsibility of the United Nations Environment Programme (UNEP), took place in Kosovo in November 2000 to evaluate the level of depleted uranium (DU) released into the environment by the use of DU ammunition during the 1999 conflict. Representatives of six different scientific organisations took part in the mission and a total

Umberto Sansone; Pier Roberto Danesi; Sabrina Barbizzi; Maria Belli; Michael Campbell; Stefania Gaudino; Guogang Jia; Rita Ocone; Alessandra Pati; Silvia Rosamilia; Luisa Stellato

2001-01-01

127

Radioecological survey at selected sites hit by depleted uranium ammunitions during the 1999 Kosovo conflict.  

PubMed

A field study, organised, coordinated and conducted under the responsibility of the United Nations Environment Programme (UNEP), took place in Kosovo in November 2000 to evaluate the level of depleted uranium (DU) released into the environment by the use of DU ammunition during the 1999 conflict. Representatives of six different scientific organisations took part in the mission and a total of approximately 350 samples were collected. During this field mission, the Italian National Environmental Protection Agency (ANPA) collected water, soil, lichen and tree bark samples from different sites. The samples were analysed by alpha-spectroscopy and in some cases by inductively coupled plasma-source mass spectrometry (ICP-MS). The 234U/238U and 235U/238U activity concentration ratios were used to distinguish natural from anthropogenic uranium. This paper reports the results obtained on these samples. All water samples had very low concentrations of uranium (much below the average concentration of drinking water in Europe). The surface soil samples showed a very large variability in uranium activity concentration, namely from approximately 20 Bq kg(-1) (environmental natural uranium) to approximately 2.3 x 10(5) Bq kg(-1) (approximately 18000 mg kg(-1) of depleted uranium), with concentrations above environmental levels always due to DU. The uranium isotope measurements refer to soil samples collected at places where DU ammunition had been fired; this variability indicates that the impact of DU ammunitions is very site-specific, reflecting both the physical conditions at the time of the impact of the DU ammunition and any physical and chemical alteration which occurred since then. The results on tree barks and lichens indicated the presence of DU in all cases, showing their usefulness as sensitive qualitative bio-indicators for the presence of DU dusts or aerosols formed at the time the DU ammunition had hit a hard target. This result is particularly interesting considering that at some sites, which had been hit by DU ammunition, no DU ground contamination could be detected. PMID:11778955

Sansone, U; Danesi, P R; Barbizzi, S; Belli, M; Campbell, M; Gaudino, S; Jia, G; Ocone, R; Pati, A; Rosamilia, S; Stellato, L

2001-12-17

128

In-line assay monitor for uranium hexafluoride  

DOEpatents

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

Wallace, S.A.

1980-03-21

129

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

SciTech Connect

Highlights: • Both PET and PVC have nearly the same densities. • The best pH value will be 4 for optimizing pH values. • Malic acid gave the best results for selective separation of PET and PVC. - Abstract: 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.

Guney, Ali; Poyraz, M. Ibrahim; Kangal, Olgac, E-mail: kangal@itu.edu.tr; Burat, Firat

2013-09-15

130

Position angle and separation of binary stars selected from the Washington Double Star Catalog  

NASA Astrophysics Data System (ADS)

We report on separation and position angle measurements of binary star systems, selected from the Washington Double Star catalog. This data is acquired at the 31 inch NURO telescope, located 20 miles east of Flagstaff, Arizona. The NASACAM CCD camera, with 27-micron pixels and a field of view of 16 arc minutes is attached to the telescope when collecting the images for this project. . Then, the images are pixelized and finally, the separation and the position angle of the star system are measured. The data is then published at the Journal of Double Star Observations. This research project is part of an ongoing gathering of data that has been active for various years. We include stars with data from various years.

Muller, Rafael J.; Cersosimo, J. C.; Franco, E.; Rodriguez, R. A.; Diaz Rodriguez, M.; Rosario, M.; Nieves, Y.; Torres, B.; Rodriguez, J.; Vergara, N.

2014-01-01

131

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

132

Selective and efficient control of coherent population transfer with time-separated chirped pulses  

SciTech Connect

We propose a selective, efficient, and robust way to realize control of coherent population transfer in a {Lambda}-type four-level system with a closely spaced doublet in the final state with time-separated chirped pump pulse and Stokes pulse pair by merging stimulated Raman adiabatic passage, temporal coherent control, and chirped adiabatic passage techniques. Moreover, an arbitrary coherent superposition between the final doublet, or between the intermediate state and either of the doublets can be created. This method holds the ability to 'control with control' and has potential applications in coherent control of chemical reactions and quantum information processing.

Yang Xihua; Zhang Zhenhua; Yan Xiaona; Li Chunfang [Department of Physics, Shanghai University, Shanghai 200444 (China)

2010-03-15

133

Pervaporation membrane separation process for enhancing the selectivity of an artificial olfactory system ("electronic nose").  

PubMed

This study investigates the potential of pervaporation (a selective membrane separation technique) combined with an electronic nose based on metal oxide sensors for analyzing wine model solutions. Choosing a suitable membrane polymer, it is shown that subtle variations in aroma composition can be detected by the metal oxide sensors, even when 12% (v/v) ethanol is present in the original sample. Simulations of the composition of the permeate demonstrate that, despite the low molecular density of the permeate, the respective solute concentrations are sufficiently high to generate a reproducible and significant response from the metal oxide sensors. PMID:16402173

Schäfer, Thomas; Serrano-Santos, Maria Belén; Rocchi, Santina; Fuoco, Roger

2006-02-01

134

A recyclable supramolecular membrane for size-selective separation of nanoparticles  

NASA Astrophysics Data System (ADS)

Most practical materials are held together by covalent bonds, which are irreversible. Materials based on noncovalent interactions can undergo reversible self-assembly, which offers advantages in terms of fabrication, processing and recyclability, but the majority of noncovalent systems are too fragile to be competitive with covalent materials for practical applications, despite significant attempts to develop robust noncovalent arrays. Here, we report nanostructured supramolecular membranes prepared from fibrous assemblies in water. The membranes are robust due to strong hydrophobic interactions, allowing their application in the size-selective separation of both metal and semiconductor nanoparticles. A thin (12 µm) membrane is used for filtration (~5 nm cutoff), and a thicker (45 µm) membrane allows for size-selective chromatography in the sub-5 nm domain. Unlike conventional membranes, our supramolecular membranes can be disassembled using organic solvent, cleaned, reassembled and reused multiple times.

Krieg, Elisha; Weissman, Haim; Shirman, Elijah; Shimoni, Eyal; Rybtchinski, Boris

2011-03-01

135

Separating Metallic Beryllium from Plutonium by Selective Dissolution with Ammonium Fluoride  

SciTech Connect

Plutonium metal is stabilized for long-term storage by calcining to produce PuO{sub 2}. However, if beryllium is present, the calcined product may have a high neutron dose rate because of the {sup 9}Be({alpha},n){sup 12}C reaction in the finely divided oxide mixture. (At LLNL, inadvertent calcining of a mixture of {approx}500 g Pu/50 g Be produced a neutron source of {approx}5 R/hr.) Therefore, for health physics reasons, we would like a convenient procedure to remove beryllium from plutonium with high selectivity. Two reagents, sodium hydroxide and ammonium fluoride, were considered for aqueous processing. Each reagent selectively dissolves beryllium, which can be separated from the insoluble plutonium by decanting/filtering operations followed by water washes to remove the excess reagent. The washed plutonium is calcined for storage; the beryllium and wash fractions are solidified for disposal.

Torres, R A

2006-11-29

136

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

SciTech Connect

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

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

2003-02-25

137

Approach for selective separation of thiophenic and sulfidic sulfur compounds from petroleum by methylation/demethylation.  

PubMed

Detailed characterization of petroleum derived sulfur compounds has been challenging, due to the complex composition of the hydrocarbon matrix. A novel method was developed for selective separation of thiophenic and sulfidic compounds from petroleum. Sulfur compounds were methylated to sulfonium salts by AgBF4 and CH3I, then the polar salts were separated by precipitation from petroleum matrix. The thiophenic and sulfidic sulfonium salts were sequentially demethylated with 7-azaindole and 4-dimethylaminopyridine, obtaining original thiophenic and sulfidic compounds, respectively. The method was validated by model compounds, and applied to a diesel and a vacuum distillation petroleum fraction. Sulfur fractions were characterized by gas chromatography (GC) coupled with a sulfur chemiluminescence detector (SCD) and quadrupole mass spectrometry (MS), and high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The technique was effective to selectively obtain high-purity thiophenic and sulfidic compounds and showed rare discrimination among sulfur compounds with ranging molecular weights and degrees of unsaturation. The method would facilitate multifaceted detailed characterization of sulfur compounds in an organic complex matrix. PMID:25519193

Wang, Meng; Zhao, Suoqi; Chung, Keng H; Xu, Chunming; Shi, Quan

2015-01-20

138

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

NASA Astrophysics Data System (ADS)

This study examines how the cathode/anode surface area ratio affects the electrochemical reduction of uranium oxide in a molten Li 2O-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 Li 2O-LiCl electrolyte. A 17 kg uranium oxide electrolysis cell was set up with a cathode/anode surface area ratio of 2.6, and uranium oxide was successfully reduced to metallic uranium.

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

2011-11-01

139

Selecting a separable parametric spatiotemporal covariance structure for longitudinal imaging data.  

PubMed

Longitudinal imaging studies allow great insight into how the structure and function of a subject's internal anatomy changes over time. Unfortunately, the analysis of longitudinal imaging data is complicated by inherent spatial and temporal correlation: the temporal from the repeated measures and the spatial from the outcomes of interest being observed at multiple points in a patient's body. We propose the use of a linear model with a separable parametric spatiotemporal error structure for the analysis of repeated imaging data. The model makes use of spatial (exponential, spherical, and Matérn) and temporal (compound symmetric, autoregressive-1, Toeplitz, and unstructured) parametric correlation functions. A simulation study, inspired by a longitudinal cardiac imaging study on mitral regurgitation patients, compared different information criteria for selecting a particular separable parametric spatiotemporal correlation structure as well as the effects on types I and II error rates for inference on fixed effects when the specified model is incorrect. Information criteria were found to be highly accurate at choosing between separable parametric spatiotemporal correlation structures. Misspecification of the covariance structure was found to have the ability to inflate the type I error or have an overly conservative test size, which corresponded to decreased power. An example with clinical data is given illustrating how the covariance structure procedure can be performed in practice, as well as how covariance structure choice can change inferences about fixed effects. PMID:25293361

George, Brandon; Aban, Inmaculada

2015-01-15

140

Uranium industry annual 1998  

SciTech Connect

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

NONE

1999-04-22

141

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

142

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

143

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

144

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

145

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

PubMed Central

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

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

2010-01-01

146

Ion imprinted polymer particles for separation of yttrium from selected lanthanides.  

PubMed

Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7-dichloroquinoline-8-ol, 4-vinylpyridine, styrene, divinylbenzene and 2,2'-azobisisobutyronitrile in 2-methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y-Dy, Y-Gd and Dy-Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy-Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of approximately 25. Dy-Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid-liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 +/- 0.2 to 65.2 +/- 0.2% in a single stage of operation. PMID:16833087

Kala, Ramakrishnan; Rao, Talasila Prasada

2006-06-01

147

Separability of stimulus parameter encoding by on-off directionally selective rabbit retinal ganglion cells  

PubMed Central

The ganglion cell output of the retina constitutes a bottleneck in sensory processing in that ganglion cells must encode multiple stimulus parameters in their responses. Here we investigate encoding strategies of On-Off directionally selective retinal ganglion cells (On-Off DS RGCs) in rabbits, a class of cells dedicated to representing motion. The exquisite axial discrimination of these cells to preferred vs. null direction motion is well documented: it is invariant with respect to speed, contrast, spatial configuration, spatial frequency, and motion extent. However, these cells have broad direction tuning curves and their responses also vary as a function of other parameters such as speed and contrast. In this study, we examined whether the variation in responses across multiple stimulus parameters is systematic, that is the same for all cells, and separable, such that the response to a stimulus is a product of the effects of each stimulus parameter alone. We extracellularly recorded single On-Off DS RGCs in a superfused eyecup preparation while stimulating them with moving bars. We found that spike count responses of these cells scaled as independent functions of direction, speed, and luminance. Moreover, the speed and luminance functions were common across the whole sample of cells. Based on these findings, we developed a model that accurately predicted responses of On-Off DS RGCs as products of separable functions of direction, speed, and luminance (r = 0.98; P < 0.0001). Such a multiplicatively separable encoding strategy may simplify the decoding of these cells' outputs by the higher visual centers. PMID:21325684

Nowak, Przemyslaw; Dobbins, Allan C.; Gawne, Timothy J.; Grzywacz, Norberto M.

2011-01-01

148

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

149

Flotation selectivity of novel alkyl dicarboxylate reagents for apatite-calcite separation.  

PubMed

The investigation aims to demonstrate the conceptual thoughts behind developing mineral specific reagents for use in flotation of calcium containing ores. For this purpose, a series of dicarboxylate-based surfactants with varying distance between the carboxylate groups (one, two or three methylene groups) was synthesized. A surfactant with the same alkyl chain length but with only one carboxylate group was also synthesized and evaluated. The adsorption behavior of these new reagents on pure apatite and pure calcite surfaces was studied using Hallimond tube flotation, FTIR and ? potential measurements. The relation between the adsorption behavior of a given surfactant at a specific mineral surface and its molecular structure over a range of concentrations and pH values, as well as the region of maximum recovery, was established. It was found that one of the reagents, with a specific distance between the carboxylate groups, was much more selective for a particular mineral surface than the other homologues. For example, out of the four compounds synthesized, only the one where the carboxylate groups were separated by a single methylene group floated apatite but not calcite, whereas calcite was efficiently floated with the monocarboxylic reagent, but not with the other reagents synthesized. This selective adsorption of a given surfactant to a particular mineral surface relative to other mineral surfaces as evidenced in the flotation studies was substantiated by ? potential and infra-red spectroscopy data. PMID:25596367

Karlkvist, Tommy; Patra, Anuttam; Rao, Kota Hanumantha; Bordes, Romain; Holmberg, Krister

2015-05-01

150

Chromatographic characterization of hydrophilic interaction liquid chromatography stationary phases: hydrophilicity, charge effects, structural selectivity, and separation efficiency.  

PubMed

Fourteen commercially available particle-packed columns and a monolithic column for hydrophilic interaction liquid chromatography (HILIC) were characterized in terms of the degree of hydrophilicity, the selectivity for hydrophilic-hydrophobic substituents, the selectivity for the regio and configurational differences in hydrophilic substituents, the selectivity for molecular shapes, the evaluation of electrostatic interactions, and the evaluation of the acidic-basic nature of the stationary phases using nucleoside derivatives, phenyl glucoside derivatives, xanthine derivatives, sodium p-toluenesulfonate, and trimethylphenylammonium chloride as a set of samples. Principal component analysis based on the data of retention factors could separate three clusters of the HILIC phases. The column efficiency and the peak asymmetry factors were also discussed. These data on the selectivity for partial structural differences were summarized as radar-shaped diagrams. This method of column characterization is helpful to classify HILIC stationary phases on the basis of their chromatographic properties, and to choose better columns for targets to be separated. Judging from the retention factor for uridine, these HILIC columns could be separated into two groups: strongly retentive and weakly retentive stationary phases. Among the strongly retentive stationary phases, zwitterionic and amide functionalities were found to be the most selective on the basis of partial structural differences. The hydroxyethyl-type stationary phase showed the highest retention factor, but with low separation efficiency. Weakly retentive stationary phases generally showed lower selectivity for partial structural differences. PMID:21782195

Kawachi, Yuusuke; Ikegami, Tohru; Takubo, Hirotaka; Ikegami, Yuka; Miyamoto, Masatoshi; Tanaka, Nobuo

2011-09-01

151

Selection and Characterization of Carbon Black and Surfactants for Development of Small Scale Uranium Oxicarbide Kernels  

SciTech Connect

This report supports the effort for development of small scale fabrication of UCO (a mixture of UO{sub 2} and UC{sub 2}) fuel kernels for the generation IV high temperature gas reactor program. In particular, it is focused on optimization of dispersion conditions of carbon black in the broths from which carbon-containing (UO{sub 2} {center_dot} H{sub 2}O + C) gel spheres are prepared by internal gelation. The broth results from mixing a hexamethylenetetramine (HMTA) and urea solution with an acid-deficient uranyl nitrate (ADUN) solution. Carbon black, which is previously added to one or other of the components, must stay dispersed during gelation. The report provides a detailed description of characterization efforts and results, aimed at identification and testing carbon black and surfactant combinations that would produce stable dispersions, with carbon particle sizes below 1 {micro}m, in aqueous HMTA/urea and ADUN solutions. A battery of characterization methods was used to identify the properties affecting the water dispersability of carbon blacks, such as surface area, aggregate morphology, volatile content, and, most importantly, surface chemistry. The report introduces the basic principles for each physical or chemical method of carbon black characterization, lists the results obtained, and underlines cross-correlations between methods. Particular attention is given to a newly developed method for characterization of surface chemical groups on carbons in terms of their acid-base properties (pK{sub a} spectra) based on potentiometric titration. Fourier-transform infrared (FTIR) spectroscopy was used to confirm the identity of surfactants, both ionic and non-ionic. In addition, background information on carbon black properties and the mechanism by which surfactants disperse carbon black in water is also provided. A list of main physical and chemical properties characterized, samples analyzed, and results obtained, as well as information on the desired trend or range of values generally associated with better dispersability, is provided in the Appendix. Special attention was given to characterization of several surface-modified carbon blacks produced by Cabot Corporation through proprietary diazonium salts chemistry. As demonstrated in the report, these advanced carbons offer many advantages over traditional dispersions. They disperse very easily, do not require intensive mechanical shearing or sonication, and the particle size of the dispersed carbon black aggregates is in the target range of 0.15-0.20 {micro}m. The dispersions in water and HMTA/urea solutions are stable for at least 30 days; in conditions of simulated broth, the dispersions are stable for at least 6 hours. It is proposed that the optimization of the carbon black dispersing process is possible by replacing traditional carbon blacks and surfactants with surface-modified carbon blacks having suitable chemical groups attached on their surface. It is recognized that the method advanced in this report for optimizing the carbon black dispersion process is based on a limited number of tests made in aqueous and simulated broth conditions. The findings were corroborated by a limited number of tests carried out with ADUN solutions by the Nuclear Science and Technology Division at Oak Ridge National Laboratory (ORNL). More work is necessary, however, to confirm the overall recommendation based on the findings discussed in this report: namely, that the use of surface-modified carbon blacks in the uranium-containing broth will not adversely impact the chemistry of the gelation process, and that high quality uranium oxicarbide (UCO) kernels will be produced after calcination.

Contescu, Cristian I [ORNL

2006-01-01

152

Vortex-aided inertial microfluidic device for continuous particle separation with high size-selectivity, efficiency, and purity  

PubMed Central

In this paper, we report an inertial microfluidic device with simple geometry for continuous extraction of large particles with high size-selectivity (<2??m), high efficiency (?90%), and high purity (>90%). The design takes advantage of a high-aspect-ratio microchannel to inertially equilibrate cells and symmetric chambers for microvortex-aided cell extraction. A side outlet in each chamber continuously siphons larger particles, while the smaller particles or cells exit through the main outlet. The design has several advantages, including simple design, small footprint, ease of paralleling and cascading, one-step operation, and continuous separation with ultra-selectivity, high efficiency and purity. The described approach is applied to manipulating cells and particles for ultra-selective separation, quickly and effectively extracting larger sizes from the main flow, with broad applications in cell separations. PMID:24404052

Wang, Xiao; Zhou, Jian; Papautsky, Ian

2013-01-01

153

Zinc silicate-bonded diethyldithiocarbamate — a selective adsorbent for separating transition metal ions and preconcentration of palladium(II)  

Microsoft Academic Search

A new chelating adsorbent, zinc silicate-bonded diethyldithiocarbamate (DTC) has been prepared for the separation and preconcentration of some transition metal ions. The distribution coefficients (Kd values) of 15 metal ions have been estimated in solution at various pH's and some quantitative separations have been achieved. The high selectivity for Pd(II) has been utilized for its preconcentration from dilute aqueous solutions;

D. K. Singh; N. K. Mishra

1991-01-01

154

Alternate site selection process for UMTRA (Uranium Mill Tailings Remedial Action) project sites  

SciTech Connect

The purpose of this document is to describe the guidelines and processes to be used by the Department of Energy (DOE) with input from the affected states and tribes to select alternate disposal sites in compliance with each established cooperative agreement. This document supersedes two previous DOE documents, Criteria for Evaluating Disposal Sites (DOE, 1982) and Alternate Site Selection Process (ASSP) for UMTRA Project Sites (DOE, 1986). This revision of the ASSP was prepared in response to the proposed groundwater protection standards that amend 40 CF 192. The principal modifications are to the ASSP screening criteria for hydrological and geological conditions at candidate disposal sites. The revised screening and selection criteria will assist the project in selecting disposal sites where the probability of compliance with the proposed groundwater standards is high. The ASSP described in Section 2.0 consists of three phases: Phases I -- designation of a search region; Phase II -- preliminary screening of the designated search region; and Phase III -- identification and evaluation of candidate sites. Section 3.0 discusses how the results of the ASSP will be reported. This process provides a technically sound and publicly defensible approach for identifying potentially suitable disposal sites. 4 refs., 1 fig., 3 tabs.

Not Available

1988-06-01

155

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

PubMed

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

Koda, Yuta; Terashima, Takaya; Sawamoto, Mitsuo

2014-11-01

156

High resolution capillary column development for selective separations in gas chromatography  

SciTech Connect

A review of techniques for the preparation of high resolution capillary columns for gas chromatography is presented. Surface roughing, surface deactivation, stationary phase coating, and stationary phase crosslinking are discussed. Criteria for the selection of GC stationary phases and procedures for column evaluation are presented. A method is proposed for the isolation and determination of crude oil contamination in tropical plants and sediments. The method uses Florisil (TM) chromatography for the simultaneous clean-up and fractionation of aliphatic and aromatic hydrocarbons. Crosslinked SE-54 fused silica capillary columns prepared in our laboratory were employed for all GC separations. Mass spectrometry was used to help locate and identify specific oil components despite the intense background of the chromatogram. Crude oil components were identified in extracts of mangrove plant samples collected from the Peck Slip oil spill site at Media Munda, Puerto Rico. Crude oil components were also identified in sediment samples from controlled oil spill of Prudhoe Bay oil at Laguna de Chiriqui, Panama.

Przybyciel, M.

1985-01-01

157

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

158

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

159

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

160

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

161

Separated at birth: the interlinked origins of Darwin's unconscious selection concept and the application of sexual selection to race.  

PubMed

This essay traces the interlinked origins of two concepts found in Charles Darwin's writings: "unconscious selection," and sexual selection as applied to humanity's anatomical race distinctions. Unconscious selection constituted a significant elaboration of Darwin's artificial selection analogy. As originally conceived in his theoretical notebooks, that analogy had focused exclusively on what Darwin later would call "methodical selection," the calculated production of desired changes in domestic breeds. By contrast, unconscious selection produced its results unintentionally and at a much slower pace. Inspiration for this concept likely came from Darwin's early reading of works on both animal breeding and physical ethnology. Texts in these fields described the slow and unplanned divergence of anatomical types, whether animal or human, under the guidance of contrasting ideals of physical perfection. These readings, it is argued, also led Darwin to his theory of sexual selection as applied to race, a theme he discussed mainly in his book The Descent of Man (1871). There Darwin described how the racial version of sexual selection operated on the same principle as unconscious selection. He thereby effectively reunited these kindred concepts. PMID:18175603

Alter, Stephen G

2007-01-01

162

Computational identification of a metal organic framework for high selectivity membrane-based CO2/CH4 separations  

E-print Network

during synthesis. A range of experimental and modeling studies have examined MOFs in adsorption-based, diffusion of CO2 is typically slower than CH4. In MOFs of this kind, membrane-based separations, which relyComputational identification of a metal organic framework for high selectivity membrane-based CO2

Nair, Sankar

163

Effect of ?-irradiation of ion imprinted polymer (IIP) particles for the preconcentrative separation of dysprosium from other selected lanthanides  

Microsoft Academic Search

The selectivity of zinc with respect to copper ions was improved by ?-irradiation of surface imprinted polymer particles. We have reported the preparation of dysprosium ion imprinted polymer (IIP) particles by covalent approach during molecular imprinting. This paper reports the results obtained after ?-irradiation of dysprosium IIP particles and their use in the preconcentration\\/separation of dysprosium from dilute aqueous solutions

V. M Biju; J. Mary Gladis; T. Prasada Rao

2003-01-01

164

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...

165

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

166

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

PubMed Central

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

2013-01-01

167

A critical overview of non-aqueous capillary electrophoresis. Part I: mobility and separation selectivity.  

PubMed

This two-part review critically gives an overview on the theoretical and practical advances in non-aqueous capillary electrophoresis (NACE) achieved over the recent five years. Part I starts out by reviewing the aspects relevant to electromigration in organic solvents and evaluates potential advantages of the latter in comparison to aqueous solvent systems. The crucial role of solubility for the species involved in CE - analytes and back ground electrolyte constituents - is discussed both for ionic and neutral compounds. The impact of organic solvents on the electrophoretic and electroosmotic mobility and on the ionization (pKa values) of weak acids and bases is highlighted. Special emphasis is placed on methanol, acetonitrile and mixtures of these solvents, being the most frequent employed media for NACE applications. In addition, also solvents less commonly used in NACE will be covered, including other alcohols, amides (formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide), propylene carbonate, dimethylsulphoxide, and nitromethane. The discussions address the consequences of dramatic pKa shifts frequently seen for weak acids and bases, and the important contributions of medium-specific electroosmotic flow (EOF) to electromigration in nonaqueous media. Important for NACE, the role of the water content on pKa and mobility is analyzed. Finally, association phenomena rather specific to nonaqueous solvents (ion pairing, homo- and heteroconjugation) will be addressed, along with their potential advantages for the development of NACE separation protocols. It is pointed out that this review is not intended as a listing of all papers that have been published on NACE in the period mentioned above. It rather deals with general aspects of migration and selectivity in organic solvent systems, and discusses - critically - examples from the literature with particular interest to the topic. An analog discussion about the role of the solvent on efficiency will be presented in Part II. PMID:24468239

Kenndler, Ernst

2014-03-28

168

In-line assay monitor for uranium hexafluoride  

DOEpatents

An in-line assay monitor for determining the content of uranium-235 in a uranium hexafluoride gas isotopic separation system is provided which removes the necessity of complete access to the operating parameters of the system for determining the uranium-235 content. The monitor is intended for uses such as safeguard applications to assure that weapons grade uranium is not being produced in an enrichment cascade. The method and monitor for carrying out the method involve cooling of a radiation pervious chamber connected in fluid communication with the selected point in the system to withdraw a specimen and solidify the specimen in the chamber. The specimen is irradiated by means of an ionizing radiation source of energy different from that of the 185 keV gamma emissions from the uranium-235 present in the specimen. Simultaneously, the gamma emissions from the uranium-235 of the specimen and the source emissions transmitted through the sample are counted and stored in a multiple channel analyzer. The uranium-235 content of the specimen is determined from the comparison of the accumulated 185 keV energy counts and the reference energy counts. The latter is used to measure the total uranium isotopic content of the specimen. The process eliminates the necessity of knowing the system operating conditions and yet obtains the necessary data without need for large scintillation crystals and sophisticated mechanical designs.

Wallace, Steven A. (Knoxville, TN)

1981-01-01

169

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

PubMed

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

Nii, Susumu; Oka, Naoyoshi

2014-11-01

170

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

171

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

PubMed

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

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

2014-11-10

172

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

PubMed

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

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

2013-12-15

173

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

174

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

EPA Science Inventory

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

175

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

EPA Science Inventory

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

176

Solidphase extraction using Empore™ Radium Rad Disks to separate radium from thorium  

Microsoft Academic Search

A new method is presented for rapid and selective enrichment of radium in natural samples using 225Ra as a chemical yield tracer. The new technique allows a complete separation of the target nuclide from the sample matrix with high separation factors for thorium and uranium. The use of EmporeÔ Radium Rad Disks combines the easy handling of column chromatography with

S. Purkl; A. Eisenhauer

2003-01-01

177

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

178

Uranium Ore Uranium is extracted  

E-print Network

Milling of Uranium Ore Uranium is extracted from ore with strong acids or bases. The uranium is concentrated in a solid substance called"yellowcake." Chemical Conversion Plants convert the uranium in yellowcake to uranium hexafluoride (UF6 ), a compound that can be made into nuclear fuel. Enrichment

179

Selection of genetic and phenotypic features associated with inflammatory status of patients on dialysis using relaxed linear separability method.  

PubMed

Identification of risk factors in patients with a particular disease can be analyzed in clinical data sets by using feature selection procedures of pattern recognition and data mining methods. The applicability of the relaxed linear separability (RLS) method of feature subset selection was checked for high-dimensional and mixed type (genetic and phenotypic) clinical data of patients with end-stage renal disease. The RLS method allowed for substantial reduction of the dimensionality through omitting redundant features while maintaining the linear separability of data sets of patients with high and low levels of an inflammatory biomarker. The synergy between genetic and phenotypic features in differentiation between these two subgroups was demonstrated. PMID:24489753

Bobrowski, Leon; ?ukaszuk, Tomasz; Lindholm, Bengt; Stenvinkel, Peter; Heimburger, Olof; Axelsson, Jonas; Bárány, Peter; Carrero, Juan Jesus; Qureshi, Abdul Rashid; Luttropp, Karin; Debowska, Malgorzata; Nordfors, Louise; Schalling, Martin; Waniewski, Jacek

2014-01-01

180

Regeneration of hydrofluoric acid and selective separation of Si(IV) in a process for producing ultra-clean coal  

Microsoft Academic Search

A technique for selectively separating approximately 65 wt.% of the Si(IV) in coal has been developed. The technique first uses aqueous hydrofluoric acid (HF) to react with aluminosilicates and quartz to form fluoride complexed Al and Si species in solution. Aluminium cations, in the form of Al(NO3)3, are then added to the solution to complex fluoride as AlF2+ and hydrolyse

Karen M. Steel; John W. Patrick

2004-01-01

181

Electromigrative separation techniques in forensic science: combining selectivity, sensitivity, and robustness.  

PubMed

In this review we introduce the advantages and limitations of electromigrative separation techniques in forensic toxicology. We thus present a summary of illustrative studies and our own experience in the field together with established methods from the German Federal Criminal Police Office rather than a complete survey. We focus on the analytical aspects of analytes' physicochemical characteristics (e.g. polarity, stereoisomers) and analytical challenges including matrix tolerance, separation from compounds present in large excess, sample volumes, and orthogonality. For these aspects we want to reveal the specific advantages over more traditional methods. Both detailed studies and profiling and screening studies are taken into account. Care was taken to nearly exclusively document well-validated methods outstanding for the analytical challenge discussed. Special attention was paid to aspects exclusive to electromigrative separation techniques, including the use of the mobility axis, the potential for on-site instrumentation, and the capillary format for immunoassays. The review concludes with an introductory guide to method development for different separation modes, presenting typical buffer systems as starting points for different analyte classes. The objective of this review is to provide an orientation for users in separation science considering using capillary electrophoresis in their laboratory in the future. PMID:25381613

Posch, Tjorben Nils; Pütz, Michael; Martin, Nathalie; Huhn, Carolin

2015-01-01

182

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

183

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

184

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

PubMed

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

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

2013-09-01

185

Hyperlayer separation in hollow fiber flow field-flow fractionation: effect of membrane materials on resolution and selectivity.  

PubMed

Hollow fiber flow FFF (HF FlFFF) has recently shown its capability to separate and characterize the size of submicrometer particles and has demonstrated the potential to be developed into a disposable flow FFF channel. In this work, HF FIFFF was used for the hyperlayer separation of micron-sized particles and the separation capability was examined by using various hollow fiber membrane materials (Polysulfones, cPVC, and PAN). From the experiments, PAN (polyacrylonitriles) showed an outstanding performance in particle separation compared to the other membranes. By orienting the fiber module in an upright direction, the upstream flow migration reduced band broadening of eluted peaks. When the efficiency of the PAN hollow fiber system was tested by varying the ratio of outflow-rate to radial flow-rate, it was found that optimum separation in hyperlayer HF FlFFF can be obtained at the ratio of about 6-7. From the examination of retention at or around steric inversion diameter, it was observed that experiments showed a good agreement with predictions by semi-empirical calculation. In hyperlayer HF FlFFF the diameter based selectivity values were shown to be 1.2-1.7 depending on the type of membranes and the field strength (the radial flow-rate) conditions. PMID:11990991

Min, Byung Ryul; Kim, Seok Jin; Ahn, Kyu-Hong; Moon, Myeong Hee

2002-03-15

186

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

PubMed

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

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

2013-12-01

187

Separation of selected cations by liquid membranes. Progress report, 1 December 1983-31 August 1984  

SciTech Connect

Objective is to elucidate the chemical principles responsible for the cation selectivity and permeability of liquid membranes containing macrocyclic carriers. During the past year, the research program has focused on three specific areas: investigation of cation transport in lipid vesicles as models of liquid surfactant (emulsion) membrane transport, transport of metal cations by calixarene carriers, and final preparation of a manuscript describing selective cation transport from ternary mixtures.

Christensen, J.J.

1984-09-26

188

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

PubMed

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

Vovk, Irena; Simonovska, Breda; Vuorela, Heikki

2005-06-10

189

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

PubMed

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

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

2014-08-13

190

Separation selectivity of some ethylenediaminetetraacetic acid and cyclohexane-1,2-diaminetetraacetic acid complexes in column and ion electrokinetic chromatography.  

PubMed

The complexes of Mn2+, Cd2+, Fe3+, Pb2+, Ni2+, Co2+, Zn2+ and Cu2+ with EDTA and cyclohexane-1,2-diaminetetraacetic acid (CDTA) were separated and detected in column and ion electrokinetic chromatography with suppressed conductivity and direct UV detection, respectively. In column ion chromatography (IC) these complexes were separated on an IonPac AS4A anion-exchange column (Dionex, USA). Parameters of carrier electrolyte, which were examined in the ion electrokinetic chromatography (IEKC) mode, include polymer and sulfate concentrations. In IEKC separation selectivity of complexes with poly(diallyldimethylammonium) cation as modifier is similar as for an IonPac AS4A column both for EDTA and CDTA chelates. It was shown that the ion-exchange capacity of the electrokinetic system is more than 100-times lower than the capacity of the IC column for the same peak resolution. In comparison with column main advantages of electrokinetic version are high separation efficiency (220,000-390,000 theoretical plates) and the absence of the analyte interaction with the sorbent matrix. PMID:10457487

Krokhin, O V; Adamov, A V; Hoshino, H; Shpigun, O A; Yotsuyanagi, T

1999-07-30

191

Optimization of conditions for selective dissociation of trifluorobromomethane molecules in carbon isotope separation  

SciTech Connect

An experimental study was made of the characteristics of multiphoton dissociation of CF/sub 3/Br molecules when /sup 13/CF/sub 3/Br is excited under collisional conditions. For the first time, measurements were made of the selectivity of multiphoton excitation of a natural mixture of /sup 12/C and /sup 13/C isotopes, and its dependences on the excitation frequency and buffer pressure were determined. It was observed that the selectivity of excitation of /sup 13/CF/sub 3/Br molecules in the low-frequency wing of the ..nu../sub 1/ band is governed by the absorption at the 3..nu../sub 3/ overtone and its thermal bands, and the dissociation selectivity is governed exclusively by the conditions of excitation of the molecules in the ..nu../sub 1/ band. The optimum regime for selective dissociation of CF/sub 3/Br in terms of energy consumption matched to the parameters of existing CO/sub 2/ lasers was determined. At a radiation energy density of 2.6 J/cm/sup 2/ the energy consumption is approx.260 eV per /sup 13/C atom. This regime may be used as the first stage in laser enrichment of carbon isotopes.

Avatkov, O.N.; Laptev, V.B.; Ryabov, E.A.; Furzikov, N.P.

1985-03-01

192

Separation of selected cations by liquid membranes. Progress report, 1 December 1982-31 July 1985  

SciTech Connect

The objective of our research program is to elucidate the chemical principles which are responsible for the cation selectivity and permeability of liquid membranes containing macrocyclic carriers. During the past three years, the research program has focused on three specific areas: investigation of cation transport in liquid surfactant (emulsion) membrane systems and in lipid vesicles which can be considered as models of such transport; selective cation transport from multiple cation mixtures; and transport of metal cations by proton-ionizable carriers. In the first area, both the macrocyclic carrier in the membrane phase and an irreversible cation complexing agent in the receiving phase have been found to be necessary for effective transport in both membrane systems. In the second area, work was completed to determine the cation permeabilities of membranes when two to four cations are present simultaneously. The results were compared to the equilibrium model of transport developed earlier. It was found that the equilibrium model correctly describes the data in those cases where cations of the same charge are mixed in the source phase, but that the correspondence between model and experimental results is not always good in the case of mixed electrolytes. This result has been rationalized in terms of the large difference in partition coefficient between cations of different charge as compared to those of identical charge. In the third area, new substituted calixarenes and new 4-hydroxy-pyridone macrocycles were synthesized and the transport of alkali metal cations by these carriers was investigated. The calixarenes were found to be selective for Cs/sup +/, with calix(4)arene providing the greatest Cs/sup +/ selectivity. On the other hand, the pyridone macrocyclic carrier was found to be selective for K/sup +/. The transport mechanism for both carriers involves coupled M/sup +/-H/sup +/ transport in the membrane system. 18 refs., 1 fig.

Christensen, J.J.; Izatt, R.M.

1985-07-31

193

Selectively Permeable Polymers and Gas-separation Membranes: Structure and Transport Properties  

NASA Astrophysics Data System (ADS)

The relationship between the permeability coefficients and the sorption and diffusion properties of highly elastic and vitreous polymers has been examined. The concept of free volume can be used to interpret the characteristics of transport not only in highly elastic but also in vitreous polymers. The properties are discussed of the basic polymeric materials of gas-separation membranes; heterophase polymeric systems such as block copolymers and polymers with liquid-crystalline additives and additives undergoing specific interaction, and also quasi-liquid membranes with components facilitating the transport of gases. The bibliography contains 84 references.

Durgar'yan, S. G.; Yampol'skii, Yu P.; Plate, Nikolai A.

1988-06-01

194

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

195

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

196

Separating Effects of Gene Flow and Natural Selection along an Environmental Gradient  

Microsoft Academic Search

Genetic differentiation along environmental clines is often observed as a result of interplay between gene flow and natural\\u000a selection. In order to understand the relative roles of these processes in shaping this differentiation, we designed a study\\u000a in which we used two approaches that have not previously been combined, the Q\\u000a ST–F\\u000a ST comparison and crossbreeding. We examined (1) interpopulation

Sergei Volis; Yong-Hong Zhang

2010-01-01

197

Electric fields separation by phase selection in modulation spectroscopy of photoreflectance  

Microsoft Academic Search

The built-in electric fields in a MBE grown ?-doped GaAs homojunction have been investigated by the techniques of photoreflectance and phase suppression. Two Franz-Keldysh oscillation features originating from two different fields in the structure superimpose with each other in the photoreflectance spectrum. By properly selecting the reference phase of the lock-in amplifier, one of the features can be suppressed, thus

Y. C. Wang; W. Y. Chou; W. C. Hwang; J. S. Hwang

1997-01-01

198

Selective Separation of Thorium Using Ion Imprinted Chitosan?Phthalate Particles via Solid Phase Extraction  

Microsoft Academic Search

We have studied a new method for the preparation of Th(IV)?imprinted chitosan?phthalate particles, which can considerably enhance the adsorption capacity and selectivity of thorium ions. In this study, chitosan?phthalate was used as the complexing monomer, Th(IV) as template, epichlorohydrin as crosslinking agent. Initially, chitosan was modified with phthalic anhydrides and complex formation occured between carboxylic acid functional groups and Th(IV)

Ebru Birlik; Sibel Büyüktiryaki; Arzu Ersöz; Adil Denizli; R?dvan Say

2006-01-01

199

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

NASA Astrophysics Data System (ADS)

Preparation of Zn2+ ion-imprinted polymer (Zn-IIP) nanoparticles is presented in this report. The Zn-IIP nanoparticles are prepared by dissolving stoichiometric amounts of zinc nitrate and selected chelating ligand, 3,5,7,20,40-pentahydroxyflavone, in 15 mL ethanol-acetonitrile (2:1; v/v) mixture as a porogen solvent in the presence of ethylene glycol-dimethacrylate (EGDMA) as cross-linking, methacrylic acid (MAA) as functional monomer, and 2,2-azobisisobutyronitrile (AIBN) as initiator. After polymerization, Cavities in the polymer particles corresponding to the Zn2+ ions were created by leaching the polymer in HCl aqueous solution. The synthesized IIPs were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal analysis techniques. Also, the pH range for rebinding of Zn2+ ion on the IIP and equilibrium binding time were optimized, using flame atomic absorption spectrometry. In selectivity study, it was found that imprinting results increased affinity of the material toward Zn2+ ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIPs were repeatedly used and regenerated for six times without any significant decrease in polymer binding affinities. Finally, the prepared sorbent was successfully applied to the selective recognition and determination of zinc ion in different real samples.

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

2014-01-01

200

Physicochemical Characterization of Capstone Depleted Uranium Aerosols I: Uranium Concentration in Aerosols as a Function of Time and Particle Size  

SciTech Connect

During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing depleted uranium were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time particularly within the first minute after the shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% 30 min after perforation. In the Bradley vehicle, the initial (and maximum) uranium concentration was lower than those observed in the Abrams tank and decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in the cyclone samplers, which collected aerosol continuously for 2 h post perforation. The percentages of uranium mass in the cyclone separator stages from the Abrams tank tests ranged from 38% to 72% and, in most cases, varied with particle size, typically with less uranium associated with the smaller particle sizes. Results with the Bradley vehicle ranged from 18% to 29% and were not specifically correlated with particle size.

Parkhurst, MaryAnn; Cheng, Yung-Sung; Kenoyer, Judson L.; Traub, Richard J.

2009-03-01

201

Spectrophotometric determination of uranium using dibenzoylmethane  

Microsoft Academic Search

A procedure for the spectrophotometric determination of uranium has been developed in support of minerals research being conducted by the Bureau of Mines. Uranium is separated from the sample by tributylphosphate extraction from acid solution containing added aluminum nitrate and (ethylene dinitrilo)-tetraacetic acid solutions. The colored uranium-dibenzoylmethane complex is developed in the organic phase by adding an ethanol solution of

M. M. Jones; J. S. MacDuff; A. B. Whitehead

1980-01-01

202

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

203

Liquid-liquid extraction and spectrophotometric determination of uranium with n-phenyl-3-styrylacrylohydroxamic acid (PSAHA)  

Microsoft Academic Search

A rapid, selective and sensitive liquid-liquid extraction and spectrophotometric method for the separation and microgram determination of uranium using PSAHA is described. Uranium is extracted with PSAHA into chloroform at pH 6.0–6.8. The U-PSAHA chelate is orange red in color having maximum absorbance at 410 nm and molar absorptivity 1.2·104l·mol–1·cm–1. The system obeys Beer's Law in the range of 1.2

Y. K. Agrawal; D. B. Upadhyaya; S. P. Chudasama

1993-01-01

204

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

Microsoft Academic Search

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

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

2011-01-01

205

Airflow-field-induced sandwich-type membrane of block copolymer for selective ion separation.  

PubMed

A simple and effective airflow method to prepare sandwich-type block copolymer films is reported. The films are composed of three layers: vertically oriented nanocylinders align in both upper and bottom layers and irregular nanocylinders exist in the bulk of the film. The vertically oriented nanocylinders in both sides can provide high accessibility to ions and ensures the exchange of chemical species between the membrane and external environment, while the irregularly oriented nanocylinders in the middle part of the film can prolong the pathway of ions transportation and enhance ions selectivity. PMID:24497315

Shan, Feng; Lu, Xuemin; Guan, Junfang; Lu, Qinghua; Feng, Xingliang

2014-04-01

206

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

SciTech Connect

Abstract: The rare gases krypton, xenon, and radon pose both an economic opportunity and a potential environmental hazard. Xenon is used in commercial lighting, medical imaging, and anesthesia, and can sell for $5,000 per kilogram. Radon, by contrast, Is naturally radioactive and the second largest cause of lung cancer, and radioactive xenon, 133Xe, was a major pollutant released In the Fukushima Daiichi Nuclear Power Plant disaster. We describe an organic cage molecule that can capture xenon and radon with unprecedented selectivity, suggesting new technologies for environmental monitoring, removal of pollutants, or the recovery of rare, valuable elements from air.

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

2014-10-31

207

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

208

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

NASA Astrophysics Data System (ADS)

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

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

1997-05-01

209

Selective separation of cis-trans geometrical isomers of beta-carotene via CO2 supercritical fluid extraction.  

PubMed

We investigated a novel method for the selective separation of beta-carotene isomers from a freeze-dried powder of the algae Dunaliella bardawil using supercritical fluid extraction. The separation method relies on the different dissolution rate of the 9Z and all-E isomers of beta-carotene in SC-CO(2). At first, the equilibrium solubility of the two isomers in SC-CO(2) was determined at the extraction conditions of 44.8 MPa and 40 degrees C. The solubility of the 9Z isomer was found to be nearly 4 times higher than that of the all-E isomer (1.92 x 10(-5) g all-E isomer/g CO(2) compared to 7.64 x 10(-5) g 9Z isomer/g CO(2)). When supercritical fluid extraction was applied to a carotenoid concentrate from the algae (29 wt% beta-carotene) or a freeze-dried powder of the algae (3.1% beta-carotene), a selective separation of the 9Z/all-E isomers of beta-carotene was obtained. Thirty-nine percent recovery of beta-carotene with 80% purity of 9Z isomer was achieved at the initial stages of extraction (40 mL CO(2)). The extraction rate of beta-carotene from the freeze-dried algae powder was slower than that from the carotenoid concentrate, resulting in a reduction in the recovery and purity of the 9Z isomer. This indicates that even at the initial stage of the extraction the internal mass resistance is significant. Isomer purity and recovery could be enhanced upon grinding of the algae powder. PMID:12209772

Gamlieli-Bonshtein, Iris; Korin, Eli; Cohen, Smadar

2002-10-20

210

Uranium droplet core nuclear rocket  

NASA Technical Reports Server (NTRS)

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

Anghaie, Samim

1991-01-01

211

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

212

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

213

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

SciTech Connect

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

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

2002-02-25

214

Hydrothermal alteration of organic matter in uranium ores, Elliot Lake, Canada: Implications for selected organic-rich deposits  

SciTech Connect

Organic matter in the uraniferous Matinenda Formation, Elliot Lake, is preserved in the forms of syngenetic kerogen and solid bitumen as it is in many of the Oklo uranium deposits and in the Witwatersrand gold-uranium ores. The Elliot Lake kerogen is a vitrinite-like material considered to be remnants of the Precambrian cyanobacterial mats. The kerogen at Elliot Lake has reflectances (in oil) ranging from 2.63-7.31% RO{sub max}, high aromaticity, relatively low (0.41-0.60) atomic H/C ratios, and it contains cryptocrystalline graphite. Bitumen, present primarily as dispersed globules (up to 0.5 mm dia.), has reflectances from 0.72-1.32% RO{sub max}, atomic H/C ratios of 0.71-0.81, and is somewhat less aromatic than the kerogen. Overall similarity in molecular compositions indicates that liquid bitumen was derived from kerogen by processes similar to hydrous pyrolysis. The carbon isotopic composition of kerogen ({minus}15.62 to {minus}24.72%), and the now solid bitumen ({minus}25.91 to {minus}33.00%) are compatible with these processes. Despite having been subjected to several thermal episodes, ca. 2.45 Ga old kerogen of microbiological origin here survived as testimony of the antiquity of life on Earth. U-Pb isotopic data from discrete kerogen grains at Elliot Lake form a scattered array intersecting concordia at 2130 {+-} 100 Ma, correspond to the Nipissing event. U-Pb systems were totally reset by this event. Uranium and lead show subsequently partial mobility, the average of which is indicated by the lower concordia intersect of 550 {+-} 260 Ma. The migrated bitumen contains virtually no uranium and thorium but has a large excess of {sup 206}Pb, which indicates that the once liquid bitumen must have acted as a sink for mobile intermediate decay products of {sup 238}U. Emplacement of the Nipissing diabase may have been responsible for producing the bitumen and, indirectly, for its enrichment in {sup 206}Pb as a result of outgassing of {sup 222}Rn.

Mossman, D.J. [Mount Allison Univ., Sackville (Canada)] [Mount Allison Univ., Sackville (Canada); Nagy, B. [Univ. of Arizona, Tucson (United States)] [Univ. of Arizona, Tucson (United States); Davis, D.W. [Royal Ontario Museum, Toronto, Ontario (Canada)] [Royal Ontario Museum, Toronto, Ontario (Canada)

1993-07-01

215

SPECTROPHOTOMETRIC DETERMINATION OF URANIUM IN ORES WITH 8QUINOLINOL  

Microsoft Academic Search

A method for the sensitive and rapid spectrophotometric determination of ; uranium in ores using 8-quinolinol was developed. Uranium is separated by ; extraction with tributylphosphate-kerosene from nitric acid solution. After the ; back-extraction of uranium with ammonium carbonate solution, uranium is ; determined spectrophotometrically with 8-quinolinol. When 1 gram of sample is ; taken, as little as 0.005% of

K. Motojima; H. Yoshida; T. Imahashi

1962-01-01

216

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

217

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

PubMed Central

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 (2.5×102 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 N2-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.

2010-01-01

218

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

NASA Technical Reports Server (NTRS)

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

Wu, Te-Kao (Inventor)

1996-01-01

219

Selective Breeding for Infant Rat Separation-Induced Ultrasonic Vocalizations: Developmental Precursors of Passive and Active Coping Styles  

PubMed Central

Human depression and anxiety disorders show inherited biases across generations, as do antisocial disorders characterized by aggression. Each condition is preceded in children by behavioral inhibition or aggressive behavior, respectively, and both are characterized by separation anxiety disorders. In affected families, adults and children exhibit different forms of altered autonomic nervous system regulation and hypothalamic-pituitary-adrenal activity in response to stress. Because it is difficult to determine mechanisms accounting for these associations, animal studies are useful for studying the fundamental relationships between biological and behavioral traits. Pharmacologic and behavioral studies suggest that infant rat ultrasonic vocalizations (USV) are a measure of an early anxiety-like state related to separation anxiety. However, it was not known whether or not early ultrasound emissions in infant rats are markers for genetic risk for anxiety states later in life. To address these questions, we selectively bred two lines of rats based on high and low rates of USV to isolation at postnatal (P) 10 days of age. To our knowledge, ours is the only laboratory that has ever selectively bred on the basis of an infantile trait related to anxiety. The High and Low USV lines show two distinct sets of patterns of behavior, physiology and neurochemistry from infancy through adulthood. As adults High line rats demonstrate “anxious”/“depressed” phenotypes in behavior and autonomic nervous system (ANS) regulation to standard laboratory tests. In Lows, on the other hand, behavior and autonomic regulation are consistent with an “aggressive” phenotype. The High and Low USV lines are the first genetic animal models implicating long-term associations of contrasting “coping styles” with early attachment responses. They thus present a potentially powerful model for examining gene-environment interactions in the development of life-long affective regulation. PMID:17543397

Brunelli, Susan A.; Hofer, Myron A.

2009-01-01

220

Methyl parathion imprinted polymer nanoshell coated on the magnetic nanocore for selective recognition and fast adsorption and separation in soils.  

PubMed

Core-shell magnetic methyl parathion (MP) imprinted polymers (Fe3O4@MPIPs) were fabricated by a layer-by-layer self-assembly process. In order to take full advantage of the synergistic effect of hydrogen-binding interactions and ?-? accumulation between host and guest for molecular recognition, methacrylic acid and 4-vinyl pyridine were chosen as co-functional monomers and their optimal proportion were investigated. The core-shell and crystalline structure, morphology and magnetic properties of Fe3O4@MPIPs were characterized. The MP-imprinted nanoshell was almost uniform and about 100nm thick. Binding experiments demonstrated that Fe3O4@MPIPs possessed excellent binding properties, including high adsorption capacity and specific recognition, as well as fast adsorption kinetics and a fast phase separation rate. The equilibration adsorption capacity reached up to 9.1mg/g, which was 12 times higher than that of magnetic non-imprinted polymers, while adsorption reached equilibrium within 5min at a concentration of 0.2mmol/L. Furthermore, Fe3O4@MPIPs successfully provided selective separation and removal of MP in soils with a recovery and detection limit of 81.1-87.0% and 5.2ng/g, respectively. PMID:24275470

Xu, Shiying; Guo, Changjuan; Li, Yongxian; Yu, Zerong; Wei, Chaohai; Tang, Youwen

2014-01-15

221

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

223

PURIFICATION OF URANIUM FROM URANIUM/MOLYBDENUM ALLOY  

SciTech Connect

The Savannah River Site will recycle a nuclear fuel comprised of 90% uranium-10% molybdenum by weight. The process flowsheet calls for dissolution of the material in nitric acid to a uranium concentration of 15-20 g/L without the formation of precipitates. The dissolution will be followed by separation of uranium from molybdenum using solvent extraction with 7.5% tributylphosphate in n-paraffin. Testing with the fuel validated dissolution and solubility data reported in the literature. Batch distribution coefficient measurements were performed for the extraction, strip and wash stages with particular focus on the distribution of molybdenum.

Pierce, R; Ann Visser, A; James Laurinat, J

2007-10-15

224

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

225

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

226

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

227

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

228

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

PubMed

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

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

2008-08-01

229

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

2011-07-01

230

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

231

Speciation and spectrophotometric determination of uranium in seawater  

Microsoft Academic Search

A series of ion-exchange and extraction procedures for the separation of uranium from seawater samples and subsequent spectrophotometric determination of uranium in seawater by means of arsenazo(III) is described. According to the measurements performed by means of traced samples at every stage of separation, the yield of the pre-analytical procedures is generally over 90% and the separation of uranium very

M. KONSTANTINOU; I. PASHALIDIS

232

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.degree. C. to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein. The U-Fe alloy having dissolved therein reduced metals from the spent nuclear fuel is contacted with a mixture of one or more alkali metal or alkaline earth metal halides selected from the class consisting of alkali metal or alkaline earth metal and Fe or U halide or a combination thereof to transfer transuranium actinide metals and rare earth metals to the halide salt leaving the uranium and some noble metal fission products in the U-Fe alloy and thereafter separating the halide salt and the transuranium metals dissolved therein from the U-Fe alloy and the metals dissolved therein.

Miller, William E. (Naperville, IL); Ackerman, John P. (Downers Grove, IL); Battles, James E. (Oak Forest, IL); Johnson, Terry R. (Wheaton, IL); Pierce, R. Dean (Naperville, IL)

1992-01-01

233

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

234

A Rapid Method for the Extraction and Separation of Uranium from Thorium and Other Accompanying Elements Using Octadecyl Silica Membrane Disks Modified by Tri-n-octyl Phosphine Oxide  

Microsoft Academic Search

A simple method for rapid and selective separation of uranyl ion from Th and other accompanying elements by using octadecyl silica membrane disks modified with tri-n-octyl phosphine oxide (TOPO) in the presence of 0.5 M HNO3 is presented. The influences of type and concentration of acid, nature of ligands, flow rates, and nature of stripping agents have been investigated. Maximum

MOJTABA SHAMSIPUR; YADOLLAH YAMINI; PARVIZ ASHTARI; ALI REZA KHANCHI; MOHAMMAD GHANNADI-MARAGEH

2000-01-01

235

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...

236

Selective CO 2 separation from CO 2\\/C 2H 6 mixtures by immobilized diethanolamine\\/PEG membranes  

Microsoft Academic Search

CO2 separation from a mixture of CO2\\/C2H6 through membranes containing immobilized solutions of diethanolamine (DEA) and poly (ethylene glycol) (PEG) was carried out. The effects of flow pattern, flow rates, DEA concentration and CO2 partial pressure were investigated. The addition of DEA in the membrane matrix resulted in the enhancement of CO2 transport rate across the membrane. CO2\\/C2H6 separation factors

Samit Saha; Amit Chakma

1995-01-01

237

Unusual trend of increasing selectivity and decreasing flux with decreasing thickness in pervaporation separation of ethanol/water mixtures using sodium alginate blend membranes.  

PubMed

Pervaporation membranes were produced comprising a 4:1 sodium-alginate:poly(vinyl-alcohol) polymer blend selective layer with a plasticizing agent (glycerol). Membranes were supported on a poly(acrylonitrile) mesoporous support layer and non-woven fabric base. Pervaporation separation of ethanol/water mixtures was carefully followed as a function of film thickness and time. It was found, contrary to what might be expected from literature, that these films showed increased selectivity and decreased flux as film thickness was reduced. It is argued that the morphology and structure of the polymer blend changes with thickness and that these structural changes define the efficiency of the separation in these conditions. PMID:22261269

Flynn, Eoin J; Keane, Donal; Holmes, Justin D; Morris, Michael A

2012-03-15

238

Selectivity enhancement for the separation of tocopherols and steroids by integration of highly ordered weak interaction sites along the polymer main chain.  

PubMed

A novel alternating copolymer-based organic phase was synthesized using a new N-substituted maleimide monomer for the development of alternating copolymer-grafted silica for high-performance liquid chromatographic applications. This new monomer (DGMI) was copolymerized with octadecyl acrylate (ODA) from 3-mercaptopropyltrimethoxysilane-grafted silica to produce Sil-poly(ODA-alt-DGMI). The organic phase was characterized by the elemental analysis and the diffuse reflectance infrared Fourier transform spectroscopy. Tocopherol isomers and steroids were used as analytes for the evaluation of the chromatographic selectivity profiles of this novel stationary phase. The selectivity of this column was then compared with a polymeric ODS column and previously developed another alternating copolymer-grafted silica (without the glutamide-derived moiety) column, Sil-poly(ODA-alt-N-octadecylmaleimide). The complete baseline separation of tocopherol isomers in an isocratic mode has been achieved within 25 min with the Sil-poly(ODA-alt-DGMI). The separation of eight kinds of estrogenic steroids and corticoids has also been achieved in an isocratic mode with this column. Significant differences in separation selectivity between Sil-poly(ODA-alt-DGMI) and polymeric ODS columns were observed towards the steroids, and compared with the reference columns, a better separation profile for these analytes was obtained with the Sil-poly(ODA-alt-DGMI). The results of this investigation indicated that the enhancement of selectivity of Sil-poly(ODA-alt-DGMI) towards the test analytes arose from the multiple interaction mechanism such as hydrophobic effect, carbonyl-? and hydrogen-bonding interactions, and such integrated interactions originated from the addition of two amide groups in the N-substituted maleimide monomer. PMID:22699229

Mallik, Abul K; Qiu, Hongdeng; Takafuji, Makoto; Ihara, Hirotaka

2012-07-01

239

Selective Ion Flotation Separation and Concentration of Ultra Trace Amounts of Bismuth Using Arsenazo III and Its Determination by Inductively Coupled Plasma-Atomic Emission Spectrometry  

Microsoft Academic Search

A rapid, selective, and highly sensitive froth flotation method for the separation and enrichment of ultra trace amounts of bismuth is developed. The bismuth-Arsenazo III complex is concentrated from 1000 mL of aqueous solution into the scum in the presence of cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. The proposed procedure of pre-concentration is applied prior to the determination of bismuth

Mojtaba Shamsipur; Reza Davarkhah; Rahim Hassani; Ali Reza Khanchi

2010-01-01

240

Long-term, continuous mixed-gas dry fed CO 2\\/CH 4 and CO 2\\/N 2 separation performance and selectivities for room temperature ionic liquid membranes  

Microsoft Academic Search

Previously, we reported on using room temperature ionic liquids (RTILs) in place of traditional solvents in liquid membranes and showed that stabilized RTIL-membranes outperformed standard polymers for the separations of CO2\\/CH4 and CO2\\/N2 (considering ideal gas permeabilities). Here, we report on mixed-gas permeances and selectivities for the gas pairs CO2\\/CH4 and CO2\\/N2 using continuous flows of the mixed gases at

Paul Scovazzo; Drew Havard; Mike McShea; Sarah Mixon; David Morgan

2009-01-01

241

Selective separation of palladium (II) from precious metal ions using thiosemicarbazone derivatives from acidic media by solid phase and solvent extractions  

Microsoft Academic Search

A newly reported chelating ligand, 9,10-phenanthraquinone ethylthiosemicarbazone (PET), has been used for selective separation of Pd(II) by solid phase extraction (SPE) and solvent extraction (SE) in highly acidic media. PET was chemically immobilized on aminopropylsilica gel, yielding PET-SG, and complexes of PET and PET-SG with Pd(II) were synthesized and confirmed by IR, UV, thermal and elemental analyses. Free PET forms

Mohamed M. Hassanien; Khaled S. Abou-El-Sherbini

2010-01-01

242

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

243

Uranium in Soils Integrated Demonstration: Technology summary, March 1994  

SciTech Connect

A recent Pacific Northwest Laboratory (PNL) study identified 59 waste sites at 14 DOE facilities across the nation that exhibit radionuclide contamination in excess of established limits. The rapid and efficient characterization of these sites, and the potentially contaminated regions that surround them represents a technological challenge with no existing solution. In particular, the past operations of uranium production and support facilities at several DOE sites have occasionally resulted in the local contamination of surface and subsurface soils. Such contamination commonly occurs within waste burial sites, cribs, pond bottom sediments and soils surrounding waste tanks or uranium scrap, ore, tailings, and slag heaps. The objective of the Uranium In Soils Integrated Demonstration is to develop optimal remediation methods for soils contaminated with radionuclides, principally uranium (U), at DOE sites. It is examining all phases involved in an actual cleanup, including all regulatory and permitting requirements, to expedite selection and implementation of the best technologies that show immediate and long-term effectiveness specific to the Fernald Environmental Management Project (FEMP) and applicable to other radionuclide contaminated DOE sites. The demonstration provides for technical performance evaluations and comparisons of different developmental technologies at FEMP sites, based on cost-effectiveness, risk-reduction effectiveness, technology effectiveness, and regulatory and public acceptability. Technology groups being evaluated include physical and chemical contaminant separations, in situ remediation, real-time characterization and monitoring, precise excavation, site restoration, secondary waste treatment, and soil waste stabilization.

Not Available

1994-03-01

244

Lab on valve-multisyringe flow injection system (LOV-MSFIA) for fully automated uranium determination in environmental samples.  

PubMed

The hyphenation of lab-on-valve (LOV) and multisyringe flow analysis (MSFIA), coupled to a long path length liquid waveguide capillary cell (LWCC), allows the spectrophotometric determination of uranium in different types of environmental sample matrices, without any manual pre-treatment, and achieving high selectivity and sensitivity levels. On-line separation and preconcentration of uranium is carried out by means of UTEVA resin. The potential of the LOV-MSFIA makes possible the fully automation of the system by the in-line regeneration of the column. After elution, uranium(VI) is spectrophotometrically detected after reaction with arsenazo-III. The determination of levels of uranium present in environmental samples is required in order to establish an environmental control. Thus, we propose a rapid, cheap and fully automated method to determine uranium(VI) in environmental samples. The limit of detection reached is 1.9 ?g of uranium and depending on the preconcentrated volume; it results in ppt levels (10.3 ?g L(-1)). Different water sample matrices (seawater, well water, freshwater, tap water and mineral water) and a phosphogypsum sample (with natural uranium content) were satisfactorily analyzed. PMID:21641430

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

2011-06-15

245

Preliminary study of two steps aqueous two-phase extraction combined with high performance liquid chromatography for saliva protein selective separation.  

PubMed

Saliva protein separation by one-step aqueous two-phase extraction (ATPE) in the system of 15% (mass ratio if not specified) PEG-4000/8% NaH2PO4 was presented. The proteins extracted from the top and bottom phases were separated and characterized by high performance liquid chromatography (HPLC) respectively. Under the optimized gradient elution procedure, more saliva protein peaks in the two phases were shown. Saliva protein peaks in 50 min gradient were divided into ten specific groups which were classified into six sections based on the protein distribution in the top and bottom phases. Then, the top or bottom phase was performed the second step ATPE. Possible reasons for protein partition and retention difference are discussed briefly. Results show that some proteins can be separated completely in one-step ATPE, while some can be separated in the following two-step ATPE. The combination of two steps ATPE and HPLC provides a new way to achieve selective separation. PMID:25269257

Zhao, Xinying; Qu, Feng; Qin, Hao; Luo, Aiqin

2014-06-01

246

Actinide Lanthanide Separation Process – ALSEP  

SciTech Connect

Separation of the minor actinides (Am, Cm) from the lanthanides at an industrial scale remains a significant technical challenge for closing the nuclear fuel cycle. To increase the safety of used nuclear fuel (UNF) reprocessing, as well as reduce associated costs, a novel solvent extraction process has been developed. The process allows for partitioning minor actinides, lanthanides and fission products following uranium/plutonium/neptunium removal; minimizing the number of separation steps, flowsheets, chemical consumption, and waste. This new process, Actinide Lanthanide SEParation (ALSEP), uses an organic solvent consisting of a neutral diglycolamide extractant, either N,N,N',N'-tetra(2 ethylhexyl)diglycolamide (T2EHDGA) or N,N,N',N'-tetraoctyldiglycolamide (TODGA), and an acidic extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]), dissolved in an aliphatic diluent (e.g. n-dodecane). The An/Ln co-extraction is conducted from moderate-to-strong nitric acid, while the selective stripping of the minor actinides from the lanthanides is carried out using a polyaminocarboxylic acid/citrate buffered solution at pH anywhere between 3 and 4.5. The extraction and separation of the actinides from the fission products is very effective in a wide range of HNO3 concentrations and the minimum separation factors for lanthanide/Am exceed 30 for Nd/Am, reaching > 60 for Eu/Am under some conditions. The experimental results presented here demonstrate the great potential for a combined system, consisting of a neutral extractant such as T2EHDGA or TODGA, and an acidic extractant such as HEH[EHP], for separating the minor actinides from the lanthanides.

Gelis, Artem V.; Lumetta, Gregg J.

2014-01-29

247

Uranium Phosphates  

NASA Astrophysics Data System (ADS)

The methods of preparation, stability in solution and in the solid state, and composition of the crystalline hydrates of uranyl and uranium(IV) orthophosphates and condensed phosphates have been reviewed. The structures of these compounds have been discussed; they are three-dimensional polymers with a uranyl-phosphate framework. The polymerisation of the phosphate anion on thermal decomposition has been discussed. Condensed uranyl polyphosphates are unstable when kept, and are capable of undergoing dehydration, the extent of which increases with increase in the length of the phosphate chain and increase in the uranium concentration. The bibliography contains 199 references.

Kobets, L. V.; Umreiko, D. S.

1983-06-01

248

THE SPECTROPHOTOMETRIC DETERMINATION OF URANIUM WITH DIBENZOYLMETHANE  

Microsoft Academic Search

Description is given of a simple direct spectrophotometric determination ; of uranium with dibenzoylmethane in combination with tributyl phosphate, which is ; selected as the extractant of uranium because of its popularity. The procedure ; was applied to the determination of U in U ores and in monazite. One advantage ; of the method is that change in acidity does

Yoshimi Umezaki

1963-01-01

249

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

250

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

2011-01-01

251

Enantiomeric separation of tapentadol by capillary electrophoresis-Study of chiral selectivity manipulation by various types of cyclodextrins.  

PubMed

The chiral recognition of the centrally acting analgesic agent tapentadol and its isomers with various cyclodextrins (CDs) was studied by capillary electrophoresis, focusing on the migration order of four stereoisomers. In the case of non-charged hydroxypropylated CDs (2-hydroxypropyl-?-CD, 2-hydroxypropyl-?-CD) the beta derivative was able to discriminate the S,R- and R,S-isomers in acidic background electrolyte, whereas the gamma allowed the separation of S,S- and R,R-tapentadol, respectively. Dual CD system containing both hosts was used to separate all of four isomers. Negatively charged sulfated-?-CD at 1.0% (w/v) concentration in 100mM sodium borate buffer (pH 9.5) was capable of separating the isomers with favorable enantiomer migration order and the optimized method was able to determine 0.15% of chiral impurities of tapentadol in the presence of the last migrating clinically important R,R-isomer. PMID:25527976

Znaleziona, Joanna; Fej?s, Ida; Šev?ík, Juraj; Douša, Michal; Béni, Szabolcs; Maier, Vít?zslav

2015-02-01

252

Molecular recognition principles and stationary-phase characteristics of topoisomer-selective chemoaffinity materials for chromatographic separation of circular plasmid DNA topoisomers.  

PubMed

We recently discovered the molecular recognition capability of a quinine carbamate ligand attached to silica as a powerful chemoaffinity material for the chromatographic separation of circular plasmid topoisomers of different linking numbers. In this paper we develop structure-selectivity relationship studies to figure out the essential structural features for topoisomer recognition. By varying different moieties of the original cinchonan-derived selector, it was shown that intercalation by the quinoline moiety of the ligand as assumed initially as the working hypothesis is not an essential feature for topoisomer recognition during chromatography. We found that the key elements for topoisomer selectivity are the presence of a rigid weak anion-exchange site and a H-donor site separated from each other in a defined distance by a 4-atom spacer. Additionally, incorporation of the weak anion-exchange site into a cyclic ring structure provides greater rigidity of the ligand molecule and turned out to be advantageous, if not mandatory, for (close to) baseline separation. PMID:22191385

Mahut, Marek; Lindner, Wolfgang; Lämmerhofer, Michael

2012-01-18

253

Transport and separation of Ag(+) and Zn(2+) by donnan dialysis through a monovalent cation selective membrane.  

PubMed

Donnan Dialysis of Ag(+) and Zn(2+) was investigated through a cation exchange membrane (CMS Neosepta) when a proton concentration difference was maintained between the two sides of the membrane. Developed for the production of brine from sea water, CMS Neosepta showed a higher permeability to monovalent than to bivalent cations. Several physico-chemical parameters have been determined (electrical resistance, membrane potential, sorption of electrolytes, Zn(2+) and Ag(+) diffusion coefficients). The flux of Ag(+) and the diffusion potential in the membrane increase with HNO(3) concentrations. Ag(+) and Zn(2+) can be separated because of the preferential membrane transfer for Ag(+). PMID:18967293

Cherif, A T; Gavach, C; Molenat, J; Elmidaoui, A

1998-08-01

254

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

SciTech Connect

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

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

2013-10-01

255

A generic analysis of energy use and solvent selection for CO2 separation from post-combustion flue gases  

USGS Publications Warehouse

A thermodynamic calculation was performed to determine the theoretical minimum energy used to separate CO2 from a coal combustion flue gas in a typical adsorption-desorption system. Under ideal conditions, the minimum energy required to separate CO2 from post-combustion flue gas and produce pure CO2 at 1 atmospheric pressure was only about 1183 kJ/kg CO2. This amount could double with the addition of the driving forces of mass and heat transfer and the adverse impacts of absorption heat release on adsorption capacity. Thermodynamic analyses were also performed for the aqueous amine-based absorption process. Two CO2 reaction mechanisms, the carbamate formation reaction with primary/secondary amines and the CO2 hydration reaction with tertiary amines, were included in the absorption reaction. The reaction heat, sensible heat, and stripping heat were all important to the total heat requirement. The heat use of an ideal tertiary amine amounted to 2786 kJ/kg, compared to 3211 kJ/kg for an ideal primary amine. The heat usage of an ideal amine was about 20% lower than that of commercially available amines. Optimizing the absorption process configuration could further reduce energy use. This is an abstract of a paper presented at the 2008 AIChE Spring National Meeting (New Orleans, LA 4/6-10/2008).

Lu, Y.; Chen, S.; Rostam-Abadi, M.

2008-01-01

256

Inorganic arsenic speciation in groundwater samples using electrothermal atomic spectrometry following selective separation and cloud point extraction.  

PubMed

A method has been developed for speciation of total, total inorganic and organic arsenic (As) species in groundwater samples. The inorganic species of As((III,V)) were separated from organic forms by adsorbing on alumina (Al(2)O(3)) whereas the organic As was eluted out. The retained inorganic As species was eluted by 0.2 M HCl. Then eluent As(III) and As(V) were formed as complexes with ammonium pyrrolidinedithiocarbamate (APDC) and molybdate, respectively. Then As(III)-PDC and As(V)-molybdate complexes were quantitatively extracted into a non-ionic surfactant Triton X-114. The total As was determined by conventional preconcentration procedures. The resulting solutions of each method were determined by ETAAS with modifier. The main factors affecting the separation and cloud point extraction (CPE) were investigated in detail. The limits of detection values were found as 0.04 and 0.20 µg L(-1) for As(III) and As(V), respectively, whereas limits of quantification were observed as 0.13 and 0.33 µg L(-1) for As(III) and As(V), respectively. Standard addition method confirmed the accuracy. The recoveries of As(III) and As(V) were found in the range of 98 - 99%. The proposed method was applied to groundwater samples collected from different areas of Sukkur district. PMID:21478622

Baig, Jameel A; Kazi, Tasneem G; Arain, Mohammad B; Shah, Abdul Q; Kandhro, Ghulam A; Afridi, Hassan I; Khan, Sumaira; Kolachi, Nida F; Wadhwa, Sham K

2011-01-01

257

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

SciTech Connect

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

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

2012-01-01

258

Investigation on the Effect of Ultrasonic Pretreatment on Selective Separation of Iron Values from Iron Ore Tailings by Flocculation  

Microsoft Academic Search

Selective flocculation studies were carried out on Barsuan iron ore tailings having 50.5% iron, 7.2% alumina, and 7.8% silica in the absence and presence of ultrasonication at different experimental conditions using sodium hexametaphosphate as a dispersant and starch as a flocculant. The imposition of ultrasonication resulted in a marked improvement in grade as well as recovery. The results indicate that

B. P. Singh; R. Singh

1997-01-01

259

VOLATILE FLUORIDE PROCESS FOR SEPARATING PLUTONIUM FROM OTHER MATERIALS  

Microsoft Academic Search

The separation of plutonium from uranium and\\/or tission products by ; formation of the higher fluorides of uranium and\\/or plutonium is discussed. ; Neutronirradiated uranium metal is first convcrted to the hydride. This hydrided ; product is then treatced with fluorine at about 315 deg C to form and volatilize ; UF⁶ leaving plutonium behind. The plutonium may then be

F. H. Spedding; A. S. Newton

1959-01-01

260

VOLATILE FLUORIDE PROCESS FOR SEPARATING PLUTONIUM FROM OTHER MATERIALS  

Microsoft Academic Search

The separation of plutonium from uranium and\\/or fission products by ; formation of the higher fluorides off uranium and\\/or plutonium is described. ; Neutronirradiated uranium metal is first converted to the hydride. This hydrided ; product is then treated with fluorine at about 315 deg C to form and volatilize ; UFâ leaving plutonium behind. Thc plutonium may then be

F. H. Spedding; A. S. Newton

1959-01-01

261

Map Separates  

USGS Publications Warehouse

U.S. Geological Survey (USGS) topographic maps are printed using up to six colors (black, blue, green, red, brown, and purple). To prepare your own maps or artwork based on maps, you can order separate black-and-white film positives or negatives for any color printed on a USGS topographic map, or for one or more of the groups of related features printed in the same color on the map (such as drainage and drainage names from the blue plate.) In this document, examples are shown with appropriate ink color to illustrate the various separates. When purchased, separates are black-and-white film negatives or positives. After you receive a film separate or composite from the USGS, you can crop, enlarge or reduce, and edit to add or remove details to suit your special needs. For example, you can adapt the separates for making regional and local planning maps or for doing many kinds of studies or promotions by using the features you select and then printing them in colors of your choice.

U.S. Geological Survey

2001-01-01

262

Alga-Derived Substrates Select for Distinct Betaproteobacterial Lineages and Contribute to Niche Separation in Limnohabitans Strains?  

PubMed Central

We examined the proportions of major Betaproteobacteria subgroups within bacterial communities in diverse nonaxenic, monospecific cultures of algae or cyanobacteria: four species of cryptophyta (genera Cryptomonas and Rhodomonas), four species of chlorophyta (genera Pediastrum, Staurastrum, and Chlamydomonas), and two species of cyanobacteria (genera Dolichospermum and Aphanizomenon). In the cryptophyta cultures, Betaproteobacteria represented 48 to 71% of total bacteria, the genus Limnohabitans represented 18 to 26%, and the Polynucleobacter B subcluster represented 5 to 16%. In the taxonomically diverse chlorophyta group, the genus Limnohabitans accounted for 7 to 45% of total bacteria. In contrast, cyanobacterial cultures contained significantly lower proportions of the Limnohabitans bacteria (1 to 3% of the total) than the cryptophyta and chlorophyta cultures. Notably, largely absent in all of the cultures was Polynucleobacter necessarius (Polynucleobacter C subcluster). Subsequently, we examined the growth of Limnohabitans strains in the presence of different algae or their extracellular products (EPP). Two strains, affiliated with Limnohabitans planktonicus and Limnohabitans parvus, were separately inoculated into axenic cultures of three algal species growing in an inorganic medium: Cryptomonas sp., Chlamydomonas noctigama, and Pediastrum boryanum. The Limnohabitans strains cocultured with these algae or inoculated into their EPP consistently showed (i) pronounced population growth compared to the control without the algae or EPP and (ii) stronger growth stimulation of L. planktonicus than of L. parvus. Overall, growth responses of the Limnohabitans strains cultured with algae were highly species specific, which suggests a pronounced niche separation between two closely related Limnohabitans species likely mediated by different abilities to utilize the substrates produced by different algal species. PMID:21873481

Šimek, Karel; Kasalický, Vojt?ch; Zapom?lová, Eliška; Hor?ák, Karel

2011-01-01

263

Dissociation of transactivation from transrepression by a selective glucocorticoid receptor agonist leads to separation of therapeutic effects from side effects  

PubMed Central

Glucocorticoids (GCs) are the most commonly used antiinflammatory and immunosuppressive drugs. Their outstanding therapeutic effects, however, are often accompanied by severe and sometimes irreversible side effects. For this reason, one goal of research in the GC field is the development of new drugs, which show a reduced side-effect profile while maintaining the antiinflammatory and immunosuppressive properties of classical GCs. GCs affect gene expression by both transactivation and transrepression mechanisms. The antiinflammatory effects are mediated to a major extent via transrepression, while many side effects are due to transactivation. Our aim has been to identify ligands of the GC receptor (GR), which preferentially induce transrepression with little or no transactivating activity. Here we describe a nonsteroidal selective GR-agonist, ZK 216348, which shows a significant dissociation between transrepression and transactivation both in vitro and in vivo. In a murine model of skin inflammation, ZK 216348 showed antiinflammatory activity comparable to prednisolone for both systemic and topical application. A markedly superior side-effect profile was found with regard to increases in blood glucose, spleen involution, and, to a lesser extent, skin atrophy; however, adrenocorticotropic hormone suppression was similar for both compounds. Based on these findings, ZK 216348 should have a lower risk, e.g., for induction of diabetes mellitus. The selective GR agonists therefore represent a promising previously undescribed class of drug candidates with an improved therapeutic index compared to classical GCs. Moreover, they are useful tool compounds for further investigating the mechanisms of GR-mediated effects. PMID:14694204

Schäcke, Heike; Schottelius, Arndt; Döcke, Wolf-Dietrich; Strehlke, Peter; Jaroch, Stefan; Schmees, Norbert; Rehwinkel, Hartmut; Hennekes, Hartwig; Asadullah, Khusru

2004-01-01

264

Charge state-selective separation of peptides by reversible modification of amino groups and strong cation-exchange chromatography: evaluation in proteomic studies using peptide-centric database searches.  

PubMed

Here we describe an integrated approach for the selective separation of peptides from complex mixtures using strong cation-exchange chromatography. The procedure exploits the charge differences produced by reversible modification of primary amino groups in peptides, enabling their separation into three major fractions: 1) neutral peptides 2) peptides with one positive charge and 3) peptides with 2 or more positive charges. The procedure demonstrated an excellent selectivity which allowed restricted MS/MS ion searches with peptide-centric databases. PMID:21596166

Betancourt, Lázaro H; Sánchez, Aniel; Pérez, Yasset; Fernandez de Cossio, Jorge; Gil, Jeovanis; Toledo, Patricia; Iguchi, Seiji; Aimoto, Saburo; González, Luis J; Padrón, Gabriel; Takao, Toshifumi; Besada, Vladimir

2011-09-01

265

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

NASA Astrophysics Data System (ADS)

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

Rathore, Deepali; Dodds, Eric D.

2014-09-01

266

Effect of stationary phase structure on retention and selectivity tuning in the high-throughput separation of tocopherol isomers by HPLC.  

PubMed

Four stationary phases containing different groups such as: C18, C30, alkylamide, and cholesterolic, were presented for simultaneous HPLC analysis of structural isomers of tocopherol. Especially, the influence of stationary phase structure and properties on tuning of the highly selective HPLC separation of beta- and gamma-tocopherol pair demonstrating, respectively, para- and ortho- arrangement of methyl substituents on the 6-chromanol ring, has been elucidated. It was pointed out that selectivity of each stationary phase has been a result of modulation in the mass transfer and set of unspecific interactions in the tertiary system comprising analyte <==> stationary phase <==> mobile phase. Differences in observed retention and specific selectivity of tocopherols together with the stationary phase structure investigations indicated that a spatial organization changing of chemically bonded ligands as predominantly a solvation consequence. Additional molecular modeling studies preliminary explained some of these complicated supramolecular phenomena which caused that cholesterolic stationary phase offered beneficial performance in screening of tocopherols by HPLC and biomimetic studies of not completely recognized interactions of tocopherol isomers and biological membranes. PMID:15200386

Buszewski, Boguslaw; Krupczynska, Katarzyna; Bazylak, Grzegorz

2004-06-01

267

Meniscus membranes for separations  

DOEpatents

Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

Dye, Robert C. (Irvine, CA); Jorgensen, Betty (Jemez Springs, NM); Pesiri, David R. (Aliso Viejo, CA)

2004-01-27

268

Meniscus Membranes For Separation  

DOEpatents

Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

Dye, Robert C. (Irvine, CA); Jorgensen, Betty (Jemez Springs, NM); Pesiri, David R. (Aliso Viejo, CA)

2005-09-20

269

Dynamic Properties of Shock Loaded Uranium Foils  

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

270

Organic Separation Test Results  

SciTech Connect

Separable organics have been defined as “those organic compounds of very limited solubility in the bulk waste and that can form a separate liquid phase or layer” (Smalley and Nguyen 2013), and result from three main solvent extraction processes: U Plant Uranium Recovery Process, B Plant Waste Fractionation Process, and Plutonium Uranium Extraction (PUREX) Process. The primary organic solvents associated with tank solids are TBP, D2EHPA, and NPH. There is concern that, while this organic material is bound to the sludge particles as it is stored in the tanks, waste feed delivery activities, specifically transfer pump and mixer pump operations, could cause the organics to form a separated layer in the tank farms feed tank. Therefore, Washington River Protection Solutions (WRPS) is experimentally evaluating the potential of organic solvents separating from the tank solids (sludge) during waste feed delivery activities, specifically the waste mixing and transfer processes. Given the Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste acceptance criteria per the Waste Feed Acceptance Criteria document (24590-WTP-RPT-MGT-11-014) that there is to be “no visible layer” of separable organics in the waste feed, this would result in the batch being unacceptable to transfer to WTP. This study is of particular importance to WRPS because of these WTP requirements.

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

2014-09-22

271

Plutonium recovery from spent reactor fuel by uranium displacement  

DOEpatents

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 fission products including plutonium. A voltage is applied across the anode and cathode electrolytically to transfer uranium and plutonium from the anode to the electrolyte while uranium values in the electrolyte electrolytically deposit as uranium metal on the solid cathode in an amount equal to the uranium and plutonium transferred from the anode causing the electrolyte to have a second ratio of plutonium chloride to uranium chloride. Then the solid cathode with the uranium metal deposited thereon is removed and molten cadmium having uranium dissolved therein is brought into contact with the electrolyte resulting in chemical transfer of plutonium values from the electrolyte to the molten cadmium and transfer of uranium values from the molten cadmium to the electrolyte until the first ratio of plutonium chloride to uranium chloride is reestablished.

Ackerman, J.P.

1992-03-17

272

Plutonium recovery from spent reactor fuel by uranium displacement  

DOEpatents

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 including plutonium. A voltage is applied across the anode and cathode electrolytically to transfer uranium and plutonium from the anode to the electrolyte while uranium values in the electrolyte electrolytically deposit as uranium metal on the solid cathode in an amount equal to the uranium and plutonium transferred from the anode causing the electrolyte to have a second ratio of plutonium chloride to uranium chloride. Then the solid cathode with the uranium metal deposited thereon is removed and molten cadmium having uranium dissolved therein is brought into contact with the electrolyte resulting in chemical transfer of plutonium values from the electrolyte to the molten cadmium and transfer of uranium values from the molten cadmium to the electrolyte until the first ratio of plutonium chloride to uranium chloride is reestablished.

Ackerman, John P. (Downers Grove, IL)

1992-01-01

273

Uranium: a basic evaluation  

Microsoft Academic Search

All energy sources and technologies, including uranium and the nuclear industry, are needed to provide power. Public misunderstanding of the nature of uranium and how it works as a fuel may jeopardize nuclear energy as a major option. Basic chemical facts about uranium ore and uranium fuel technology are presented. Some of the major policy decisions that must be made

Crull

2009-01-01

274

Increasing the Accuracy in the Measurement of the Minor Isotopes of Uranium: Care in Selection of Reference Materials, Baselines and Detector Calibration  

NASA Astrophysics Data System (ADS)

The minor isotopes of uranium (U-233, U-234, U-236) are increasingly useful for tracing a variety of processes: movement of anthropogenic nuclides in the environment (ref 1), sources of uranium ores (ref 2), and nuclear material attribution (ref 3). We report on improved accuracy for U-234/238 and U-236/238 by supplementing total evaporation protocol TIMS measurement on Faraday detectors (ref 4)with multiplier measurement for the minor isotopes. Measurement of small signals on Faraday detectors alone is limited by noise floors of the amplifiers and accurate measurement of the baseline offsets. The combined detector approach improves the reproducibility to better than ±1% (relative) for the U-234/238 at natural abundance, and yields a detection limit for U-236/U-238 of <0.2 ppm. We have quantified contribution of different factors to the uncertainties associated with these peak jumping measurement on a single detector, with an aim of further improvement. The uncertainties in the certified values for U-234 and U-236 in the uranium standard NBS U005, if used for mass bias correction, dominates the uncertainty in their isotopic ratio measurements. Software limitations in baseline measurement drives the detection limit for the U-236/U-238 ratio. This is a topic for discussion with the instrument manufacturers. Finally, deviation from linearity of the response of the electron multiplier with count rate limits the accuracy and reproducibility of these minor isotope measurements. References: (1) P. Steier et al(2008) Nuc Inst Meth(B), 266, 2246-2250. (2) E. Keegan et al (2008) Appl Geochem 23, 765-777. (3) K. Mayer et al (1998) IAEA-CN-98/11, in Advances in Destructive and Non-destructive Analysis for Environmental Monitoring and Nuclear Forensics. (4) S. Richter and S. Goldberg(2003) Int J Mass Spectrom, 229, 181-197.

Poths, J.; Koepf, A.; Boulyga, S. F.

2008-12-01

275

Method for fabricating laminated uranium composites  

DOEpatents

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

Chapman, L.R.

1983-08-03

276

Cherenkov light detection as a velocity selector for uranium fission products at intermediate energies  

NASA Astrophysics Data System (ADS)

The in-flight particle separation capability of intermediate-energy radioactive ion (RI) beams produced at a fragment separator can be improved with the Cherenkov light detection technique. The cone angle of Cherenkov light emission varies as a function of beam velocity. This can be exploited as a velocity selector for secondary beams. Using heavy ion beams available at the HIMAC synchrotron facility, the Cherenkov light angular distribution was measured for several thin radiators with high refractive indices (n = 1.9 ~ 2.1). A velocity resolution of ~10-3 was achieved for a 56Fe beam with an energy of 500 MeV/nucleon. Combined with the conventional rigidity selection technique coupled with energy-loss analysis, the present method will enable the efficient selection of an exotic species from huge amounts of various nuclides, such as uranium fission products at the BigRIPS fragment separator located at the RI Beam Factory.

Yamaguchi, T.; Enomoto, A.; Kouno, J.; Yamaki, S.; Matsunaga, S.; Suzaki, F.; Suzuki, T.; Abe, Y.; Nagae, D.; Okada, S.; Ozawa, A.; Saito, Y.; Sawahata, K.; Kitagawa, A.; Sato, S.

2014-12-01

277

Selective Separation and Extraction of Vanadium (V) Over Manganese (II) from Co-Leaching Solution of Roasted Stone Coal and Pyrolusite Using Solvent Extraction  

NASA Astrophysics Data System (ADS)

Based on the novel technology for selective separation and extraction of vanadium (V) over manganese (II) from co-leaching solution of roasted stone coal and pyrolusite using solvent extraction, the extraction effect of vanadium (V) and manganese (II) has been studied and many technical conditions have also been optimized. Meanwhile, countercurrent simulation experiments were conducted to verify the results of the experiments. The results indicated that with three countercurrent extraction stages, 99.21% vanadium (V) was extracted using 5% (v/v) N235 and 5% (v/v) secondary octyl alcohol at initial aqueous pH of 3.0 and O/A phase ratio of 1.0. Vanadium (V) could be completely stripped after three-stage countercurrent experiments with 20 wt.% NH4Cl at O/A phase ratio of 1.0. The process flow sheet for the recovery of vanadium (V), as well as manganese (II), was proposed.

Cai, Z. L.; Feng, Y. L.; Zhou, Y. Z.; Li, H. R.; Wang, W. D.

2013-11-01

278

Selectivity issues in targeted metabolomics: Separation of phosphorylated carbohydrate isomers by mixed-mode hydrophilic interaction/weak anion exchange chromatography.  

PubMed

Phosphorylated carbohydrates are important intracellular metabolites and thus of prime interest in metabolomics research. Complications in their analysis arise from the existence of structural isomers that do have similar fragmentation patterns in MS/MS and are hard to resolve chromatographically. Herein, we present selective methods for the liquid chromatographic separation of sugar phosphates, such as hexose and pentose phosphates, 2- and 3-phosphoglycerate, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, as well as glucosamine 1- and 6-phosphate utilizing mixed-mode chromatography with reversed-phase/weak anion-exchangers and a charged aerosol detector. The best results were obtained when the reversed-phase/weak anion-exchanger column was operated under hydrophilic interaction liquid chromatography elution conditions. The effects of various chromatographic parameters were examined and are discussed on the basis of a simple stoichiometric displacement model for explaining ion-exchange processes. Employed acidic conditions have led to the complete separation of ?- and ?-anomers of glucose 6-phosphate at low temperature. The anomers coeluted in a single peak at elevated temperatures (>40°C) (peak coalescence), while at intermediate temperatures on-column interconversion with a plateau in-between resolved anomer peaks was observed with apparent reaction rate constants between 0.1 and 27.8×10(-4)?s(-1). Dynamic HPLC under specified conditions enabled to investigate mutarotation of phosphorylated carbohydrates, their interconversion kinetics, and energy barriers for interconversion. A complex mixture of six hexose phosphate structural isomers could be resolved almost completely. PMID:20928924

Hinterwirth, Helmut; Lämmerhofer, Michael; Preinerstorfer, Beatrix; Gargano, Andrea; Reischl, Roland; Bicker, Wolfgang; Trapp, Oliver; Brecker, Lothar; Lindner, Wolfgang

2010-11-01

279

Yolk-shell nanostructured Fe3O4@NiSiO3 for selective affinity and magnetic separation of His-tagged proteins.  

PubMed

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

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

2014-11-12

280

Novel microorganism for selective separation of coal from ash and pyrite; First quarterly technical progress report, September 1, 1993--November 30, 1993  

SciTech Connect

This report summarizes the progress made during the first quarter of the research project entitled ``A Novel Microorganism for Selective Separation of Coal from Ash and Pyrite,`` DOE Grant No. DE-FG22-93PC93215. The objective of this project is to study the effectiveness of a novel hydrophobic microorganism, Mycobacterium phlei (M. phlei), for the selective flocculation of coal from pyrite and ash-forming minerals. During the reporting period, three different coal samples: Illinois No. 6 coal, Kentucky No. 9 coal and Pittsburgh No. 8 coal, were collected to be used in the investigation. The microorganism, M. phlei, was obtained as freeze-dried cultures and the growth characteristics of the bacteria were studied. Scanning electron microphotographs revealed that M. phlei cells are coccal in shape and are approximately 1 {mu}m in diameter. Electrokinetic measurements showed that the Illinois No. 6 and Pittsburgh No. 8 coal samples had an isoelectric point (IEP) around pH 6 whereas M. phlei had an IEP around pH 1.5. Electrokinetic measurements of the ruptured microorganisms exhibited an increase in IEP. The increase in IEP of the ruputured cells was due to the release of fatty acids and polar groups from the cell membrane.

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

1993-12-31

281

A study on synergistic effects and protonation of a selected calixarene based picolinamide ligand used in the An/Ln separation  

NASA Astrophysics Data System (ADS)

A series of liquid-liquid extraction tests was performed on the ligand hexakis(3-N-picoline-amidepropyloxy)calix[6]arene (PAR4). First, a screening campaign was carried out, in order to select the best organic solvent to be coupled to the aforementioned calixarene ligand. 2-Nitrophenyl hexyl ether (NPHE) was chosen to this purpose, and it was used in all the subsequent experiments, because of its excellent properties from both the viewpoints of calixarene solubility and ligand extracting capabilities. In solvent extraction tests, 241Am was used as representative of minor actinides, while 152Eu was employed to simulate lanthanides. Distribution coefficients and separation factors were obtained via ?-spectrometry. In addition, the synergism between the ligand and the lipophilic dicarbollide anion Cesium commo-3,3-cobalta-Bis(8,9,12 tribromo-1,2 dicarbacloso-Dodecarborane)ate(1-) (Br-Cosan) was investigated. Experimental results indicate that at pH ?2 a strong synergistic effect between the calixarene ligand and Br-Cosan takes place. At higher acidity, on the other hand, the ligand protonation dramatically affects the efficiency and selectivity of the system.

Galletta, M.; Macerata, E.; Mariani, M.; Giola, M.; Casnati, A.; D'Arpa, O.; Ungaro, R.

2006-01-01

282

Process for recovering niobium from uranium-niobium alloys  

DOEpatents

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

Wallace, S.A.; Creech, E.T.; Northcutt, W.G.

1982-09-27

283

Process for recovering niobium from uranium-niobium alloys  

DOEpatents

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

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

1983-01-01

284

Whole-rock uranium analysis by fission track activation  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

285

Uranium industry annual 1994  

SciTech Connect

The Uranium Industry Annual 1994 (UIA 1994) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing during that survey year. The UIA 1994 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 10-year period 1985 through 1994 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data collected on the ``Uranium Industry Annual Survey`` (UIAS) provide a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1994, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. A feature article, ``Comparison of Uranium Mill Tailings Reclamation in the United States and Canada,`` is included in the UIA 1994. Data on uranium raw materials activities including exploration activities and expenditures, EIA-estimated resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities, including purchases of uranium and enrichment services, and uranium inventories, enrichment feed deliveries (actual and projected), and unfilled market requirements are shown in Chapter 2.

NONE

1995-07-05

286

Enriched uranium recovery flowsheet improvements  

SciTech Connect

Savannah River uses 7.5% TBP to recover and purify enriched uranium. Adequate decontamination from fission products is necessary to reduce personnel exposure and to ensure that the enriched uranium product meets specifications. Initial decontamination of the enriched uranium from the fission products is carried out in the 1A bank, 16 stages of mixer-settlers. Separation of the enriched uranium from the fission product, /sup 95/Zr, has been adequate, but excessive solvent degradation caused by the long phase contact times in the mixer-settlers has limited the /sup 95/Zr decontamination factor (DF). An experimental program is investigating the replacement of the current 1A bank with either centrifugal contactors or a combination of centrifugal contactors and mixer-settlers. Experimental work completed has compared laboratory-scale centrifugal contactors and mixer-settlers for /sup 95/Zr removal efficiencies. Feed solutions spiked with actual plant solutions were used. The /sup 95/Zr DF was significantly better in the mixer-settlers than in the centrifugal contactors. As a result of this experimental study, a hybrid equipment flowsheet has been proposed for plant use. The hybrid equipment flowsheet combines the advantages of both types of solvent extraction equipment. Centrifugal contactors would be utilized in the extraction and initial scrub sections, followed by additional scrub stages of mixer-settlers.

Holt, D L

1986-01-01

287

Uranium mineralization in southern Victoria Land, Antarctica  

SciTech Connect

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

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

1986-01-01

288

Particle separation  

NASA Technical Reports Server (NTRS)

Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

Moosmuller, Hans (Inventor); Chakrabarty, Rajan K. (Inventor); Arnott, W. Patrick (Inventor)

2011-01-01

289

The Navajo Uranium Mining Experience, 2003-1952  

NSDL National Science Digital Library

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

Chris Shuey

290

Evolution of isotopic composition of reprocessed uranium during the multiple recycling in light water reactors with natural uranium feed  

SciTech Connect

A complex approach based on the consistent modeling of neutron-physics processes and processes of cascade separation of isotopes is applied for analyzing physical problems of the multiple usage of reprocessed uranium in the fuel cycle of light water reactors. A number of scenarios of multiple recycling of reprocessed uranium in light water reactors are considered. In the process, an excess absorption of neutrons by the {sup 236}U isotope is compensated by re-enrichment in the {sup 235}U isotope. Specific consumptions of natural uranium for re-enrichment of the reprocessed uranium depending on the content of the {sup 232}U isotope are obtained.

Smirnov, A. Yu., E-mail: a.y.smirnoff@rambler.ru; Sulaberidze, G. A. [National Research Nuclear University MEPhI (Russian Federation); Alekseev, P. N.; Dudnikov, A. A.; Nevinitsa, V. A., E-mail: neva@dhtp.kiae.ru; Proselkov, V. N.; Chibinyaev, A. V. [Russian Research Centre Kurchatov Institute (Russian Federation)

2012-12-15

291

Innovative Separations Technologies  

SciTech Connect

Reprocessing used nuclear fuel (UNF) is a multi-faceted problem involving chemistry, material properties, and engineering. Technology options are available to meet a variety of processing goals. A decision about which reprocessing method is best depends significantly on the process attributes considered to be a priority. New methods of reprocessing that could provide advantages over the aqueous Plutonium Uranium Reduction Extraction (PUREX) and Uranium Extraction + (UREX+) processes, electrochemical, and other approaches are under investigation in the Fuel Cycle Research and Development (FCR&D) Separations Campaign. In an attempt to develop a revolutionary approach to UNF recycle that may have more favorable characteristics than existing technologies, five innovative separations projects have been initiated. These include: (1) Nitrogen Trifluoride for UNF Processing; (2) Reactive Fluoride Gas (SF6) for UNF Processing; (3) Dry Head-end Nitration Processing; (4) Chlorination Processing of UNF; and (5) Enhanced Oxidation/Chlorination Processing of UNF. This report provides a description of the proposed processes, explores how they fit into the Modified Open Cycle (MOC) and Full Recycle (FR) fuel cycles, and identifies performance differences when compared to 'reference' advanced aqueous and fluoride volatility separations cases. To be able to highlight the key changes to the reference case, general background on advanced aqueous solvent extraction, advanced oxidative processes (e.g., volumetric oxidation, or 'voloxidation,' which is high temperature reaction of oxide UNF with oxygen, or modified using other oxidizing and reducing gases), and fluorination and chlorination processes is provided.

J. Tripp; N. Soelberg; R. Wigeland

2011-05-01

292

DEPLETED URANIUM TECHNICAL WORK  

EPA Science Inventory

The Depleted Uranium Technical Work is designed to convey available information and knowledge about depleted uranium to EPA Remedial Project Managers, On-Scene Coordinators, contractors, and other Agency managers involved with the remediation of sites contaminated with this mater...

293

Selective americium(III) complexation by dithiophosphinates: a density functional theoretical validation for covalent interactions responsible for unusual separation behavior from trivalent lanthanides.  

PubMed

The separation of trivalent actinides and lanthanides is a challenging task for chemists because of their similar charge and chemical behavior. Soft donor ligands like Cyanex-301 were found to be selective for the trivalent actinides over the lanthanides. Formation of different extractable species for Am(3+) and various lanthanides (viz. La(3+), Eu(3+), and Lu(3+)) was explained on the basis of their relative stabilities as compared to their corresponding trinitrato complexes calculated using the density functional method. Further, the metal-ligand complexation energy was segregated into electrostatic, Pauli repulsion, and orbital interaction components. Higher covalence in the M-S bond in the dithiophosphinate complexes as compared to the M-O bond in the nitrate complexes was reflected in the higher orbital and lower electrostatic interactions for the complexes with increasing number of dithiophosphinate ligands. Higher affinity of the dithiophosphinate ligands for Am(3+) over Eu(3+) was corroborated with higher covalence in the Am-S bond as compared to the Eu-S bond, which was reflected in shorter bond length in the case of the former and higher ligand to metal charge transfer in Am(III)-dithiophosphinate complexes. The results were found to be consistent in gas phase density functional theory (DFT) calculations using different GGA functional. More negative complexation energies in the case of Eu(3+) complexes of Me(2)PS(2)(-) as compared to the corresponding Am(3+) complexes in spite of marginally higher covalence in the Am-S bond as compared to the Eu-S bond might be due to higher ionic interaction in the Eu(3+) complexes in the gas phase calculations. The higher covalence in the Am-S bond obtained from the gas phase studies of their geometries and electronic structures solely cannot explain the selectivity of the dithiophosphinate ligands for Am(3+) over Eu(3+). Presence of solvent may also play an important role to control the selectivity as observed from higher complexation energies for Am(3+) in the presence of solvent. Thus, the theoretical results were able to explain the experimentally observed trends in the metal-ligand complexation affinity. PMID:21449541

Bhattacharyya, Arunasis; Ghanty, Tapan Kumar; Mohapatra, Prasanta Kumar; Manchanda, Vijay Kumar

2011-05-01

294

Uranium hexafluoride bibliography  

SciTech Connect

This bibliography is a compilation of reports written about the transportation, handling, safety, and processing of uranium hexafluoride. An on-line literature search was executed using the DOE Energy files and the Nuclear Science Abstracts file to identify pertinent reports. The DOE Energy files contain unclassified information that is processed at the Office of Scientific and Technical Information of the US Department of Energy. The reports selected from these files were published between 1974 and 1983. Nuclear Science Abstracts contains unclassified international nuclear science and technology literature published from 1948 to 1976. In addition, scientific and technical reports published by the US Atomic Energy Commission and the US Energy Research and Development Administration, as well as those published by other agencies, universities, and industrial and research organizations, are included in the Nuclear Science Abstracts file. An alphabetical listing of the acronyms used to denote the corporate sponsors follows the bibliography.

Burnham, S.L.

1988-01-01

295

Plant-uptake of uranium: Hydroponic and soil system studies  

USGS Publications Warehouse

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

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

2001-01-01

296

Depleted Uranium Technical Brief  

E-print Network

Depleted Uranium Technical Brief United States Environmental Protection Agency Office of Air and Radiation Washington, DC 20460 EPA-402-R-06-011 December 2006 #12;#12;Depleted Uranium Technical Brief EPA of Radiation and Indoor Air Radiation Protection Division ii #12;iii #12;FOREWARD The Depleted Uranium

297

Gibbsite/Bayerite and Uranium in Tank 41H  

SciTech Connect

A brainstorming session was held on September 10, 2002 to discuss the issue of the aluminum trihydroxide phase (gibbsite and/or bayerite) separation from uranium in Tank 41H inhibited-water-insoluble solids. If a Nuclear Criticality Safety Evaluation (NCSE) for salt dissolution is to credit the hydrogen atoms in aluminum trihydroxide for moderation, an assessment is needed to evaluate if conditions during salt dissolution, and preferably during heel removal, could adversely affect the moderating effects of gibbsite/bayerite with respect to uranium phases. This report outlines the potential mechanisms for the chemical and physical separation of gibbsite from that of uranium in the insoluble solids in Tank 41H.

Martino, C.J.

2003-01-27

298

Separations inside a cube  

E-print Network

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

A. F. F. Teixeira

2001-12-28

299

DYNAMIC PROPERTIES OF SHOCK LOADED THIN URANIUM FOILS  

SciTech Connect

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

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

2001-01-01

300

Dynamic Properties of Shock Loaded Thin Uranium Foils  

NASA Astrophysics Data System (ADS)

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

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

2002-07-01

301

Magnetic separation for soil decontamination  

SciTech Connect

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

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

1993-01-01

302

Magnetic separation for soil decontamination  

SciTech Connect

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

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

1993-02-01

303

Oxidation states of uranium in depleted uranium particles from Kuwait.  

PubMed

The oxidation states of uranium in depleted uranium (DU) particles were determined by synchrotron radiation based mu-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 mu-XANES, DU particles ranging from submicrons to several hundred micrometers were observed. The median particle size depended on sources and sampling sites; small-sized particles (median 13 microm) were identified in swipes taken from the inside of DU penetrators holes in tanks and in sandy soil collected below DU penetrators, while larger particles (median 44 microm) were associated with fire in a DU ammunition storage facility. Furthermore, the (236)U/(235)U ratios obtained from accelerator mass spectrometry demonstrated that uranium in the DU particles originated from reprocessed fuel (about 10(-2) in DU from the ammunition facility, about 10(-3) for DU in swipes). Compared to well-defined standards, all investigated DU particles were oxidized. Uranium particles collected from swipes were characterized as UO(2), U(3)O(8) or a mixture of these oxidized forms, similar to that observed in DU affected areas in Kosovo. Uranium particles formed during fire in the DU ammunition facility were, however, present as oxidation state +5 and +6, with XANES spectra similar to solid uranyl standards. Environmental or health impact assessments for areas affected by DU munitions should therefore take into account the presence of respiratory UO(2), U(3)O(8) and even UO(3) particles, their corresponding weathering rates and the subsequent mobilisation of U from oxidized DU particles. PMID:15511555

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

2005-01-01

304

MICRONUCLEI IN EPITHELIAL CELLS FROM SPUTUM OF URANIUM WORKERS  

EPA Science Inventory

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

305

Ultracapacitor separator  

DOEpatents

An ultracapacitor includes two solid, nonporous current collectors, two porous electrodes separating the collectors, a porous separator between the electrodes and an electrolyte occupying the pores in the electrodes and separator. The electrolyte is a polar aprotic organic solvent and a salt. The porous separator comprises a wet laid cellulosic material.

Wei, Chang (Niskayuna, NY); Jerabek, Elihu Calvin (Glenmont, NY); LeBlanc, Jr., Oliver Harris (Schenectady, NY)

2001-03-06

306

Selective laser ionization of radioactive Ni-isotopes  

NASA Astrophysics Data System (ADS)

A chemically selective laser ion source based on resonance ionization of atoms in a hot cavity has been applied in the study of Ni-isotopes at the CERN-ISOLDE on-line isotope separator. Laser ionization enhanced the yields of long-lived Ni-isotopes almost four orders of magnitude when compared to the yields obtained with the surface ionization mode of the source. As a result, high yields of long-lived Ni-isotopes were obtained. Separation efficiencies of 0.3 and 0.8% were obtained for Ni produced in uranium-carbide, produced from uranium-di-pthalocyanine, and Ta-foil targets, respectively. Ni was found to be released very slowly from the present target and ion source combination.

Jokinen, A.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H.; van Duppen, P.; Erdmann, N.; Jading, Y.; Köhles, S.; Kratz, K.-L.; Trautman, N.; Wöhr, A.; Fedoseyev, V. N.; Mishin, V. I.; Tikhonov, V.

1996-04-01

307

Purification of Waste Waters from the Sulfuric-Acid Scheme for Reprocessing Uranium  

Microsoft Academic Search

A technological scheme is developed for purifying waste waters from the sulfuric-acid scheme of uranium refining, including galvanochemical treatment, separation of uranium-containing residue, blowing off ammonia, separation of nonradioactive calcium sulfate, and additional extraction of fluorine and sulfate ions. This scheme will make it possible to remove contaminants from the waste waters of the special piping system of the Angarskii

Yu. V. Ostrovskii; G. M. Zabortsev; S. P. Yakobchuk; R. L. Rabinovich; A. A. Lavelin

2005-01-01

308

Determination of uranium in minerals and rocks.  

PubMed

A method is described for the determination of uranium in minerals and rocks by spectrophotometry and fluorimetry. After treatment of the sample with hydrochloric acid, uranium is separated from matrix elements by adsorption on a column of the strongly basic anion-exchange resin Dowex 1 x 8 from an organic solvent system consisting of IBMK, tetrahydrofuran and 12M hydrochloric acid (1:8:1 v v ). Following removal of iron, molybdenum and co-adsorbed elements by washing first with the organic solvent system and then with 6M hydrochloric acid, the uranium is eluted with 1M hydrochloric acid. In the eluate, uranium is determined by means of the spectrophotometric arsenazo III method or fluorimetrically. The suitability of the method for the determination of both trace and larger amounts of uranium was tested by analysing numerous geochemical reference samples with uranium contents in the range 10(-1)-10(4) ppm. In practically all cases very good agreement of results was obtained. PMID:18961856

Korkisch, J; Hübner, H

1976-04-01

309

Recovery of uranium from seawater by immobilized tannin  

SciTech Connect

Tannin compounds having multiple adjacent hydroxy groups have an extremely high affinity for uranium. To prevent the leaching of tannins into water and to improve the adsorbing characteristics of these compounds, the authors tried to immobilize tannins. The immobilized tannin has the most favorable features for uranium recovery; high selective adsorption ability to uranium, rapid adsorption rate, and applicability in both column and batch systems. The immobilized tannin can recover uranium from natural seawater with high efficiency. About 2530 ..mu..g uranium is adsorbed per gram of this adsorbent within 22 h. Depending on the concentration in seawater, an enrichment of up to 766,000-fold within the adsorbent is possible. Almost all uranium adsorbed is easily desorbed with a very dilute acid. Thus, the immobilized tannin can be used repeatedly in the adsorption-desorption process.

Sakaguchi, T.; Nakajima, A.

1987-06-01

310

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

311

separationsNOW.com  

NSDL National Science Digital Library

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

2003-01-01

312

separationsNOW.com  

NSDL National Science Digital Library

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

313

Evaporation of Enriched Uranium Solutions Containing Organophosphates  

SciTech Connect

The Savannah River Site has enriched uranium (EU) solution which has been stored for almost 10 years since being purified in the second uranium cycle of the H area solvent extraction process. The preliminary SRTC data, in conjunction with information in the literature, is promising. However, very few experiments have been run, and none of the results have been confirmed with repeat tests. As a result, it is believed that insufficient data exists at this time to warrant Separations making any process or program changes based on the information contained in this report. When this data is confirmed in future testing, recommendations will be presented.

Pierce, R.A.

1999-03-18

314

Uranium hexafluoride public risk  

SciTech Connect

The limiting value for uranium toxicity in a human being should be based on the concentration of uranium (U) in the kidneys. The threshold for nephrotoxicity appears to lie very near 3 {mu}g U per gram kidney tissue. There does not appear to be strong scientific support for any other improved estimate, either higher or lower than this, of the threshold for uranium nephrotoxicity in a human being. The value 3 {mu}g U per gram kidney is the concentration that results from a single intake of about 30 mg soluble uranium by inhalation (assuming the metabolism of a standard person). The concentration of uranium continues to increase in the kidneys after long-term, continuous (or chronic) exposure. After chronic intakes of soluble uranium by workers at the rate of 10 mg U per week, the concentration of uranium in the kidneys approaches and may even exceed the nephrotoxic limit of 3 {mu}g U per gram kidney tissue. Precise values of the kidney concentration depend on the biokinetic model and model parameters assumed for such a calculation. Since it is possible for the concentration of uranium in the kidneys to exceed 3 {mu}g per gram tissue at an intake rate of 10 mg U per week over long periods of time, we believe that the kidneys are protected from injury when intakes of soluble uranium at the rate of 10 mg U per week do not continue for more than two consecutive weeks. For long-term, continuous occupational exposure to low-level, soluble uranium, we recommend a reduced weekly intake limit of 5 mg uranium to prevent nephrotoxicity in workers. Our analysis shows that the nephrotoxic limit of 3 {mu}g U per gram kidney tissues is not exceeded after long-term, continuous uranium intake at the intake rate of 5 mg soluble uranium per week.

Fisher, D.R.; Hui, T.E.; Yurconic, M.; Johnson, J.R.

1994-08-01

315

Synthesis of Uranium Trichloride for the Pyrometallurgical Processing of Used Nuclear Fuel  

SciTech Connect

The pyroprocessing of used nuclear fuel via electrorefining requires the continued addition of uranium trichloride to sustain operations. Uranium trichloride is utilized as an oxidant in the system to allow separation of uranium metal from the minor actinides and fission products. The inventory of uranium trichloride had diminished to a point that production was necessary to continue electrorefiner operations. Following initial experimentation, cupric chloride was chosen as a reactant with uranium metal to synthesize uranium trichloride. Despite the variability in equipment and charge characteristics, uranium trichloride was produced in sufficient quantities to maintain operations in the electrorefiner. The results and conclusions from several experiments are presented along with a set of optimized operating conditions for the synthesis of uranium trichloride.

B.R. Westphal; J.C. Price; R.D. Mariani

2011-11-01

316

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2013 CFR

... 3 2013-07-01 2013-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2013-07-01

317

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2012 CFR

... 3 2012-07-01 2012-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2012-07-01

318

31 CFR 540.317 - Uranium feed; natural uranium feed.  

... 3 2014-07-01 2014-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2014-07-01

319

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2011 CFR

... 3 2011-07-01 2011-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2011-07-01

320

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2010 CFR

... 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2010-07-01

321

Development of Novel Sorbents for Uranium Extraction from Seawater  

SciTech Connect

As the uranium resource in terrestrial ores is limited, it is difficult to ensure a long-term sustainable nuclear energy technology. The oceans contain approximately 4.5 billion tons of uranium, which is one thousand times the amount of uranium in terrestrial ores. Development of technologies to recover the uranium from seawater would greatly improve the uranium resource availability, sustaining the fuel supply for nuclear energy. Several methods have been previously evaluated including solvent extraction, ion exchange, flotation, biomass collection, and adsorption; however, none have been found to be suitable for reasons such as cost effectiveness, long term stability, and selectivity. Recent research has focused on the amidoxime functional group as a promising candidate for uranium sorption. Polymer beads and fibers have been functionalized with amidoxime functional groups, and uranium adsorption capacities as high as 1.5 g U/kg adsorbent have recently been reported with these types of materials. As uranium concentration in seawater is only ~3 ppb, great improvements to uranium collection systems must be made in order to make uranium extraction from seawater economically feasible. This proposed research intends to develop transformative technologies for economic uranium extraction from seawater. The Lin group will design advanced porous supports by taking advantage of recent breakthroughs in nanoscience and nanotechnology and incorporate high densities of well-designed chelators into such nanoporous supports to allow selective and efficient binding of uranyl ions from seawater. Several classes of nanoporous materials, including mesoporous silica nanoparticles (MSNs), mesoporous carbon nanoparticles (MCNs), meta-organic frameworks (MOFs), and covalent-organic frameworks (COFs), will be synthesized. Selective uranium-binding liagnds such as amidoxime will be incorporated into the nanoporous materials to afford a new generation of sorbent materials that will be evaluated for their uranium extraction efficiency. The initial testing of these materials for uranium binding will be carried out in the Lin group, but more detailed sorption studies will be carried out by Dr. Taylor-Pashow of Savannah River National Laboratory in order to obtain quantitative uranyl sorption selectivity and kinetics data for the proposed materials. The proposed nanostructured sorbent materials are expected to have higher binding capacities, enhanced extraction kinetics, optimal stripping efficiency for uranyl ions, and enhanced mechanical and chemical stabilities. This transformative research will significantly impact uranium extraction from seawater as well as benefit DOE’s efforts on environmental remediation by developing new materials and providing knowledge for enriching and sequestering ultralow concentrations of other metals.

Lin, Wenbin; Taylor-Pashow, Kathryn

2014-01-08

322

Microbial transformation of uranium in wastes  

SciTech Connect

Contamination of soils, water, and sediments by radionuclides and toxic metals from the disposal of uranium processing wastes is a major national concern. Although much is known about the physico- chemical aspects of U, we have little information on the effects of aerobic and anaerobic microbial activities on the mobilization or immobilization of U and other toxic metals in mixed wastes. In order to understand the mechanisms of microbial transformations of uranium, we examined a contaminated pond sediment and a sludge sample from the uranium processing facility at Y-12 Plant, Oak Ridge, TN. The uranium concentration in the sediment and sludge samples was 923 and 3080 ug/g dry wt, respectively. In addition to U, the sediment and sludge samples contained high levels of toxic metals such as Cd, Cr, Cu, Hg, Pb, Ni, and Zn. The association of uranium with the various mineral fractions of the sediment and sludge was determined by selective chemical extraction techniques. Uranium was associated to varying degrees with the exchangeable carbonate, iron oxide, organic, and inert fractions in both samples. Initial results in samples amended with carbon and nitrogen indicate immobilization of U due to enhanced indigenous microbial activity under anaerobic conditions. 23 refs., 4 figs., 5 tabs.

Francis, A.J.; Dodge, C.J.; Gillow, J.B.; Cline, J.E. (Brookhaven National Lab., Upton, NY (USA); Oak Ridge Y-12 Plant, TN (USA))

1989-01-01

323

Process for continuous production of metallic uranium and uranium alloys  

DOEpatents

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

1995-06-06

324

Process for continuous production of metallic uranium and uranium alloys  

DOEpatents

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

Hayden, Jr., Howard W. (Oakridge, TN); Horton, James A. (Livermore, CA); Elliott, Guy R. B. (Los Alamos, NM)

1995-01-01

325

Nonmilitary applications of uranium  

SciTech Connect

Uranium and its alloys should be considered for any application where weight and/or strength is required, or where weight to volume is important. There is considerable literature on uranium and its alloys. The fear of handling metallic uranium should not be a factor. It is the least hazardous of all long-lived isotopes. Sound industrial hygiene practices will provide adequate protection. In general, safety controls are similar to those required for other heavy metals.

Polson, C.E.; Blasch, E.B.

1981-01-01

326

Preparation of uranium compounds  

SciTech Connect

UI.sub.3(1,4-dioxane).sub.1.5 and UI.sub.4(1,4-dioxane).sub.2, were synthesized in high yield by reacting turnings of elemental uranium with iodine dissolved in 1,4-dioxane under mild conditions. These molecular compounds of uranium are thermally stable and excellent precursor materials for synthesizing other molecular compounds of uranium including alkoxide, amide, organometallic, and halide compounds.

Kiplinger, Jaqueline L; Montreal, Marisa J; Thomson, Robert K; Cantat, Thibault; Travia, Nicholas E

2013-02-19

327

Decontamination of uranium-contaminated waste oil using supercritical fluid and nitric acid.  

PubMed

The waste oil used in nuclear fuel processing is contaminated with uranium because of its contact with materials or environments containing uranium. Under current law, waste oil that has been contaminated with uranium is very difficult to dispose of at a radioactive waste disposal site. To dispose of the uranium-contaminated waste oil, the uranium was separated from the contaminated waste oil. Supercritical R-22 is an excellent solvent for extracting clean oil from uranium-contaminated waste oil. The critical temperature of R-22 is 96.15 °C and the critical pressure is 49.9 bar. In this study, a process to remove uranium from the uranium-contaminated waste oil using supercritical R-22 was developed. The waste oil has a small amount of additives containing N, S or P, such as amines, dithiocarbamates and dialkyldithiophosphates. It seems that these organic additives form uranium-combined compounds. For this reason, dissolution of uranium from the uranium-combined compounds using nitric acid was needed. The efficiency of the removal of uranium from the uranium-contaminated waste oil using supercritical R-22 extraction and nitric acid treatment was determined. PMID:21493611

Sung, Jinhyun; Kim, Jungsoo; Lee, Youngbae; Seol, Jeunggun; Ryu, Jaebong; Park, Kwangheon

2011-07-01

328

Uranium provinces of North America; their definition, distribution, and models  

USGS Publications Warehouse

Uranium resources in North America are principally in unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits. Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate and unconformity-related deposits are, respectively, in the Blind River?Elliot Lake (BRELUP) and the Athabasca Basin (ABUP) Uranium Provinces in Canada. Sandstone uranium deposits are of two principal subtypes, tabular and roll-front. Tabular sandstone uranium deposits are mainly in upper Paleozoic and Mesozoic rocks in the Colorado Plateau Uranium Province (CPUP). Roll-front sandstone uranium deposits are in Tertiary rocks of the Rocky Mountain and Intermontane Basins Uranium Province (RMIBUP), and in a narrow belt of Tertiary rocks that form the Gulf Coastal Uranium Province (GCUP) in south Texas and adjacent Mexico. Volcanic uranium deposits are concentrated in the Basin and Range Uranium Province (BRUP) stretching from the McDermitt caldera at the Oregon-Nevada border through the Marysvale district of Utah and Date Creek Basin in Arizona and south into the Sierra de Pe?a Blanca District, Chihuahua, Mexico. Uraniferous phosphorite occurs in Tertiary sediments in Florida, Georgia, and North and South Carolina and in the Lower Permian Phosphoria Formation in Idaho and adjacent States, but only in Florida has economic recovery been successful. The Florida Phosphorite Uranium Province (FPUP) has yielded large quantities of uranium as a byproduct of the production of phosphoric acid fertilizer. Economically recoverable quantities of copper, gold, molybdenum, nickel, silver, thorium, and vanadium occur with the uranium deposits in some provinces. Many major epochs of uranium mineralization occurred in North America. In the BRELUP, uranium minerals were concentrated in placers during the Early Proterozoic (2,500?2,250 Ma). In the ABUP, the unconformity-related deposits were most likely formed initially by hot saline formational water related to diagenesis (?1,400 to 1,330 Ma) and later reconcentrated by hydrothermal events at ?1,280??1,000, ?575, and ?225 Ma. Subsequently in North America, only minor uranium mineralization occurred until after continental collision in Permian time (255 Ma). Three principal epochs of uranium mineralization occurred in the CPUP: (1) ??210?200 Ma, shortly after Late Triassic sedimentation; (2) ??155?150 Ma, in Late Jurassic time; and (3) ??135 Ma, after sedimentation of the Upper Jurassic Morrison Formation. The most likely source of the uranium was silicic volcaniclastics for the three epochs derived from a volcanic island arc at the west edge of the North American continent. Uranium mineralization occurred during Eocene, Miocene, and Pliocene times in the RMIBUP, GCUP, and BRUP. Volcanic activity took place near the west edge of the continent during and shortly after sedimentation of the host rocks in these three provinces. Some volcanic centers in the Sierra de Pe?a Blanca district within the BRUP may have provided uranium-rich ash to host rocks in the GCUP. Most of the uranium provinces in North America appear to have a common theme of close associations to volcanic activity related to the development of the western margin of the North American plate. The south and west margin of the Canadian Shield formed the leading edge of the progress of uranium source development and mineralization from the Proterozoic to the present. The development of favorable hosts and sources of uranium is related to various tectonic elements developed over time. Periods of major uranium mineralization in North America were Early Proterozoic, Middle Proterozoic, Late Triassic?Early Jurassic, Early Cretaceous, Oligocene, and Miocene. Tertiary mineralization was the most pervasive, covering most of Western and Southern North America.

Finch, Warren Irvin

1996-01-01

329

Anomalous occurrence of uranium in alpine peats, Summit County, Colorado, and results of a simple sample fractionation procedure  

USGS Publications Warehouse

Samples from Summit County, Colo., were fractionated for analyses of organic content and uranium. The uranium is related to organic content but not to type of organic matter. In one area uranium values are around 100 ppm in bulk samples and as much as 200 ppm in certain separated fractions of the samples; this is much higher than the 1-10 ppm normal uranium values for peat.

Leventhal, Joel S.; Jennings, Joan K.; Lemke, Alan J.

1978-01-01

330

Inorganic separator technology program  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

331

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

PubMed

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

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

2014-01-01

332

Removal of uranium(VI) from aqueous solution using iminodiacetic acid derivative functionalized SBA-15 as adsorbents.  

PubMed

Three different functional SBA-15 were prepared by a post-grafting method using three iminodiacetic acid derivatives of ethylenediaminetriacetic acid (ED3A), diethylenetriaminetetraacetic acid (DT4A), and 1,2-cyclohexylenedinitrilotriacetic acid (CyD3A), which were used as adsorbents for removal of uranium(vi) from aqueous solution. These materials were characterized by FT-IR, NMR, TEM, nitrogen adsorption/desorption experiments, and elemental analysis. The effect of pH, ionic strength, contact time, solid-liquid ratio, initial metal ion concentration, temperature, and coexisting ions on uranium(vi) sorption behaviors of the functionalized SBA-15 was studied. Typical sorption isotherms (Langmuir and Freundlich) were determined for the sorption process, and the maximum sorption capacity was calculated. The influence of functional groups on uranium(vi) sorption was also discussed. As a result, compared with other current U(vi) sorbents (granite, kaolin, attapulgite), SBA-15-1,2-cyclohexylenedinitrilotriacetic acid (SBA-15-CyD3A) possessed good selective sorption properties, which had potential application in separation of uranium(vi). PMID:24435450

Wang, Yu-Long; Song, Li-Juan; Zhu, Lu; Guo, Bo-Long; Chen, Su-Wen; Wu, Wang-Suo

2014-03-01

333

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability  

SciTech Connect

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

Isselhardt, B H

2011-09-06

334

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability  

NASA Astrophysics Data System (ADS)

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

Isselhardt, Brett Hallen

335

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

Microsoft Academic Search

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

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

1996-01-01

336

Analysis of Dns-amino acids by liquid chromatography. I. Selection of optimum mobile phase composition for separation of Dns-amino acids on polyvinyl acetate gel.  

PubMed

The separation of a mixture of ten Dns-amino acids (Gns-Gly, -Ala, -Val, -Leu, -Pro, -Hypro, -Met, -Ser, -Asn and -Gln) was carried out by liquid chromatography by using macroreticular polyvinyl acetate gel as a packing material. Different mobile phase systems were investigated, based mainly on mixtures of n-hexane with ethanol, methanol, chloroform, acetone, methyl ethyl ketone, ethyl acetate, dioxane and tetrahydrofuran. The solvent composition was fixed so as to elute all of the components of the sample mixture in a practical period of 2 h. Satisfactory separation of the ten components was obtained with the n-hexane-ethanol (90:10) system. The presence of methanol as a modifier in the n-hexane was effective in reducing the elution time, but the separation was not as satisfactory. Chloroform or dioxane was useful only for the separation of Ser, Asn and Gln. Acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran were not suitable for practical separations of Dns-amino acids. PMID:1150766

Yamabe, T; Takai, N; Nakamura, H

1975-02-12

337

Uranium: A Dentist's perspective  

PubMed Central

Uranium is a naturally occurring radionuclide found in granite and other mineral deposits. In its natural state, it consists of three isotopes (U-234, U-235 and U-238). On an average, 1% – 2% of ingested uranium is absorbed in the gastrointestinal tract in adults. The absorbed uranium rapidly enters the bloodstream and forms a diffusible ionic uranyl hydrogen carbonate complex (UO2HCO3+) which is in equilibrium with a nondiffusible uranyl albumin complex. In the skeleton, the uranyl ion replaces calcium in the hydroxyapatite complex of the bone crystal. Although in North India, there is a risk of radiological toxicity from orally ingested natural uranium, the principal health effects are chemical toxicity. The skeleton and kidney are the primary sites of uranium accumulation. Acute high dose of uranyl nitrate delays tooth eruption, and mandibular growth and development, probably due to its effect on target cells. Based on all previous research and recommendations, the role of a dentist is to educate the masses about the adverse effects of uranium on the overall as well as the dental health. The authors recommended that apart from the discontinuation of the addition of uranium to porcelain, the Public community water supplies must also comply with the Environmental Protection Agency (EPA) standards of uranium levels being not more than 30 ppb (parts per billion). PMID:24478959

Toor, R. S. S.; Brar, G. S.

2012-01-01

338

Uranium: A Dentist's perspective.  

PubMed

Uranium is a naturally occurring radionuclide found in granite and other mineral deposits. In its natural state, it consists of three isotopes (U-234, U-235 and U-238). On an average, 1% - 2% of ingested uranium is absorbed in the gastrointestinal tract in adults. The absorbed uranium rapidly enters the bloodstream and forms a diffusible ionic uranyl hydrogen carbonate complex (UO2HCO3+) which is in equilibrium with a nondiffusible uranyl albumin complex. In the skeleton, the uranyl ion replaces calcium in the hydroxyapatite complex of the bone crystal. Although in North India, there is a risk of radiological toxicity from orally ingested natural uranium, the principal health effects are chemical toxicity. The skeleton and kidney are the primary sites of uranium accumulation. Acute high dose of uranyl nitrate delays tooth eruption, and mandibular growth and development, probably due to its effect on target cells. Based on all previous research and recommendations, the role of a dentist is to educate the masses about the adverse effects of uranium on the overall as well as the dental health. The authors recommended that apart from the discontinuation of the addition of uranium to porcelain, the Public community water supplies must also comply with the Environmental Protection Agency (EPA) standards of uranium levels being not more than 30 ppb (parts per billion). PMID:24478959

Toor, R S S; Brar, G S

2012-01-01

339

Uranium in river water  

Microsoft Academic Search

The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains

M. R. Palmer; J. M. Edmond

1993-01-01

340

World Uranium Reserves  

NSDL National Science Digital Library

This American Energy Independence website provides a brief overview of potential supplies of uranium for nuclear energy. The author, nuclear engineer James Hopf, believes that there are large reserves of uranium available, and that more will be discovered if needed. Links to literature cited and related resources are included.

James Hopf

341

Uranium and Thorium  

ERIC Educational Resources Information Center

The results of President Carter's policy on non-proliferation of nuclear weapons are expected to slow the growth rate in energy consumption, put the development of the breeder reactor in question, halt plans to reprocess and recycle uranium and plutonium, and expand facilities to supply enriched uranium. (Author/MA)

Finch, Warren I.

1978-01-01

342

Separating Mixtures  

NSDL National Science Digital Library

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

2014-09-18

343

Investigation of Great Basin big sagebrush and black greasewood as biogeochemical indicators of uranium mineralization. Final report. National Uranium Resource Evaluation  

Microsoft Academic Search

The effects of varying phosphate concentrations in natural aqueous systems upon the uptake of uranium by big sagebrush (Artemesia tridentata subsp. tridentata) and black greasewood (Sarcobatus vermiculatus (Hook) Torr.) were investigated. Two separate growth experiments with five drip-flow hyroponic units were used and plant seedlings were grown for 60 days in solutions of varying phosphate and uranium concentrations. Successful growth

F. E. Diebold; S. McGrath

1982-01-01

344

Uranium dioxide electrolysis  

DOEpatents

This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

Willit, James L. (Batavia, IL); Ackerman, John P. (Prescott, AZ); Williamson, Mark A. (Naperville, IL)

2009-12-29

345

Spectrophotometric determination of uranium in process streams of a uranium extraction plant.  

PubMed

This paper deals with the development and standardization of procedures for the determination of uranium on a routine basis in various process streams of a uranium extraction plant, covering a wide range of concentrations from 350 g 1(-1) down to 5 mg 1(-1) using only a spectrophotometric technique. The self-absorption of uranyl ion in dilute phosphoric acid and the violet-blue colour of the UO(2)(2+)-Arsenazo III complex in 4 M HC1 were exploited for high and low concentrations of uranium, respectively. The methods described were applied to samples of varying nature such as aqueous, organics and solids, involve minimal sample preparation and do not require prior separation of uranium from impurities. The interfering impurities in different process streams were also studied. Large quantities of silica as undissolved material poses a serious interference in the case of UNS and UNF. Considerable quantities of iron in UNS, UNF, UNR and UNRC cause interference. Possible remedies in these cases are suggested. Problems with the direct spectrophotometric measurement of organic samples is discussed. The effect of the presence of large quantities of ammonium nitrate and sodium nitrate in WD samples on the determination of uranium is also discussed. The results are compared with those obtained by volumetry and X-ray fluorescence spectrometry for higher concentrations of uranium and by extraction-spectrophotometry (ethyl acetate-thiocyanate method) for lower concentrations. Relative standard deviation of 1% and 5% for high and low concentrations, respectively, were obtained, which are adequate as far as process stream samples are concerned. The compared results are in fair agreement. The problems associated with the determination of uranium in these process streams are discussed. Experimental results for 10 different process streams normally encountered in a uranium extraction plant are tabulated. PMID:18966745

Murty, B N; Jagannath, Y V; Yadav, R B; Ramamurty, C K; Syamsundar, S

1997-02-01

346

16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM RECOVERY PROCESSED RELATIVELY PURE MATERIALS AND SOLUTIONS AND SOLID RESIDUES WITH RELATIVELY LOW URANIUM CONTENT. URANIUM RECOVERY INVOLVED BOTH SLOW AND FAST PROCESSES. (4/4/66) - Rocky Flats Plant, General Manufacturing, Support, Records-Central Computing, Southern portion of Plant, Golden, Jefferson County, CO

347

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS  

E-print Network

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS by David T. Oliphant. Woolley Dean, College of Physical and Mathematical Sciences #12;ABSTRACT CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS David T. Oliphant Department of Physics and Astronomy

Hart, Gus

348

Alteration and arenization processes of granitic waste rock piles from former uranium Mines in Limousin, France.  

NASA Astrophysics Data System (ADS)

France counts approximately 200 former uranium mines, 50 of which are located in the Limousin region. Mining activities between 1945 and 2001 have generated close to 200 000 tons of waste rocks in the Limousin, with uranium levels corresponding essentially to the geological background. Waste rock piles from three former mining sites in this region, were selected according to their age, uranium content and petrological signature. These sites are part of the two-mica granitic complex of St Sylvestre massif, formed 324 million years ago. Granitic blocks that build up the waste rock piles have experienced different processes and intensities of alteration before their emplacement at the surface. These processes are responsible for the petrological heterogeneity throughout the waste rock pile at the time of construction. It is important to make a distinction within waste rocks between natural-cut-off waste rocks and economic-cut-off waste rocks. The latter represents a minority and is linked to stock prices. Natural-cut-off waste rocks contain about 20 ppm of uranium; economic-cut-off waste rocks contain about 100 to 300 ppm of uranium. The aims of this study are to 1) assess the neo-formation of U-bearing minerals hosted by these rocks, and 2) to characterize the weathering processes since the construction of the rock piles, including both mechanical and chemical processes. The structure of the waste rocks piles, from metric blocks to boulders of tens centimeters, induces an enhanced weathering rate, compared to a granitic massif. Mechanical fracturing and chemical leaching by rainwater (arenization) of the waste rocks produce a sandy-silty alteration phase. Silty-clay weathering aureoles of submetric-granitic blocks evolving into technic soil are mainly located below growing birch trees. Sampling on the rock piles was restricted to surface rocks. Samples collected consist mainly of granites, and rare lamprophyres with a high radiometric signal, thereby especially concentrated in uranium compared to the 200 000 tons of waste rock piles in the Limousin. The composition of clay minerals and the uranium content of the samples were investigated by XRD, ICP-MS, Optical microscopy, EDS and WDS punctual measurements or element mapping and SEM on both thin sections and on rock chips. The initial granite paragenesis (quartz, albite, sanidine, microcline, biotite, muscovite, apatite, rutile, zircon and monazite) was identified. Chlorite, smectite, kaolinite and secondary phosphates and sulfates are the main secondary minerals of the different stage of hydrothermal alteration and weathering. In the clay fraction, smectites are the main mineral phases. U-bearing minerals are different according to the alteration state of mine tailings. The mean content in uranium for selected samples is about 800 ppm and rises up to 5000 ppm for the separated clay fraction of the same samples. Initially and mainly hosted by monazite, uranium is found in phosphates such as autunite, or associated with smectites. Micromorphological studies reveal: • The formation of protosoils from weathering processes. • Different degrees of alteration in the rocks, smectite or kaolinite alteromorphose. • U oxy-hydroxides, nanometric minerals or coatings associated with smectite. • A complex paregenesis of submicrometric - nanometric U phosphates, suggesting uranium stabilization.

Kanzari, Aisha; Boekhout, Flora; Gérard, Martine; Galoisy, Laurence; Phrommavanh, Vannapha; Descostes, Michael

2014-05-01

349

Method for fluorination of uranium oxide  

DOEpatents

Highly pure uranium hexafluoride is made from uranium oxide and fluorine. The uranium oxide, which includes UO.sub.3, UO.sub.2, U.sub.3 O.sub.8 and mixtures thereof, is introduced together with a small amount of a fluorine-reactive substance, selected from alkali chlorides, silicon dioxide, silicic acid, ferric oxide, and bromine, into a constant volume reaction zone. Sufficient fluorine is charged into the zone at a temperature below approximately 0.degree. C. to provide an initial pressure of at least approximately 600 lbs/sq. in. at the ambient atmospheric temperature. The temperature is then allowed to rise in the reaction zone until reaction occurs.

Petit, George S. (Oak Ridge, TN)

1987-01-01

350

Computational modeling of distinct neocortical oscillations driven by cell-type selective optogenetic drive: separable resonant circuits controlled by low-threshold spiking and fast-spiking interneurons  

E-print Network

Selective optogenetic drive of fast-spiking (FS) interneurons (INs) leads to enhanced local field potential (LFP) power across the traditional “gamma” frequency band (20–80 Hz; Cardin et al., 2009). In contrast, drive to ...

Vierling-Claassen, Dorea L.

351

2013 Domestic Uranium Production Report  

E-print Network

2013 Domestic Uranium Production Report May 2014 Independent Statistics & Analysis www.eia.gov U Administration | 2013 Domestic Uranium Production Report ii Contacts This report was prepared by the staff of the Renewables and Uranium Statistics Team, Office of Electricity, Renewables, and Uranium Statistics. Questions

352

EPA Update: NESHAP Uranium Activities  

E-print Network

EPA Update: NESHAP Uranium Activities Reid J. Rosnick Environmental Protection Agency Radiation Protection Division (6608J) Washington, DC 20460 NMA/NRC Uranium Recovery Workshop July 2, 2009 #12 for underground uranium mining operations (Subpart B) EPA regulatory requirements for operating uranium mill

353

Texture in ZIRCALOY-clad uranium  

Microsoft Academic Search

An enriched (30%²³⁵U) uranium target is being fabricated for the ANL spallation neutron source (IPNS). They have measured the orientation distribution of neutron diffraction intensities (texture) of test casting made of depleted ²³⁸U. Their results indicate the presence of large grains which may swell anisotropically with radiation damage and produce a separation of the ZIRCALOY protective cladding from the surface

F. Ross; D. Reichel; A. Krawitz; M. Mueller; J. Richardson

2009-01-01

354

India's Worsening Uranium Shortage  

SciTech Connect

As a result of NSG restrictions, India cannot import the natural uranium required to fuel its Pressurized Heavy Water Reactors (PHWRs); consequently, it is forced to rely on the expediency of domestic uranium production. However, domestic production from mines and byproduct sources has not kept pace with demand from commercial reactors. This shortage has been officially confirmed by the Indian Planning Commission’s Mid-Term Appraisal of the country’s current Five Year Plan. The report stresses that as a result of the uranium shortage, Indian PHWR load factors have been continually decreasing. The Uranium Corporation of India Ltd (UCIL) operates a number of underground mines in the Singhbhum Shear Zone of Jharkhand, and it is all processed at a single mill in Jaduguda. UCIL is attempting to aggrandize operations by establishing new mines and mills in other states, but the requisite permit-gathering and development time will defer production until at least 2009. A significant portion of India’s uranium comes from byproduct sources, but a number of these are derived from accumulated stores that are nearing exhaustion. A current maximum estimate of indigenous uranium production is 430t/yr (230t from mines and 200t from byproduct sources); whereas, the current uranium requirement for Indian PHWRs is 455t/yr (depending on plant capacity factor). This deficit is exacerbated by the additional requirements of the Indian weapons program. Present power generation capacity of Indian nuclear plants is 4350 MWe. The power generation target set by the Indian Department of Atomic Energy (DAE) is 20,000 MWe by the year 2020. It is expected that around half of this total will be provided by PHWRs using indigenously supplied uranium with the bulk of the remainder provided by breeder reactors or pressurized water reactors using imported low-enriched uranium.

Curtis, Michael M.

2007-01-15

355

An ion-exchange method for selective separation of palladium, platinum and rhodium from solutions obtained by leaching automotive catalytic converters  

Microsoft Academic Search

An ion-exchange method has been developed for the separation of palladium, platinum and rhodium from a solution that is highly acidic and contains a considerable amount of lead, aluminum, iron and cerium, obtained by leaching a used honeycomb type automotive catalytic converter. A column of Amberlite IRA-93 anion-exchange resin was found appropriate to recover platinum metals from the pregnant solution.

Romulus Gaita; Sargon J. Al-Bazi

1995-01-01

356

Stereoisomers Separation  

NASA Astrophysics Data System (ADS)

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

Wieczorek, Piotr

357

Fault Separation  

NSDL National Science Digital Library

Students use gestures to explore the relationship between fault slip direction and fault separation by varying the geometry of faulted layers, slip direction, and the perspective from which these are viewed.

Ormand, Carol

358

Controlling intake of uranium in the workplace: Applications of biokinetic modeling and occupational monitoring data  

SciTech Connect

This report provides methods for interpreting and applying occupational uranium monitoring data. The methods are based on current international radiation protection guidance, current information on the chemical toxicity of uranium, and best available biokinetic models for uranium. Emphasis is on air monitoring data and three types of bioassay data: the concentration of uranium in urine; the concentration of uranium in feces; and the externally measured content of uranium in the chest. Primary Reference guidance levels for prevention of chemical effects and limitation of radiation effects are selected based on a review of current scientific data and regulatory principles for setting standards. Generic investigation levels and immediate action levels are then defined in terms of these primary guidance levels. The generic investigation and immediate actions levels are stated in terms of radiation dose and concentration of uranium in the kidneys. These are not directly measurable quantities, but models can be used to relate the generic levels to the concentration of uranium in air, urine, or feces, or the total uranium activity in the chest. Default investigation and immediate action levels for uranium in air, urine, feces, and chest are recommended for situations in which there is little information on the form of uranium taken into the body. Methods are prescribed also for deriving case-specific investigation and immediate action levels for uranium in air, urine, feces, and chest when there is sufficient information on the form of uranium to narrow the range of predictions of accumulation of uranium in the main target organs for uranium: kidneys for chemical effects and lungs for radiological effects. In addition, methods for using the information herein for alternative guidance levels, different from the ones selected for this report, are described.

Leggett, Richard Wayne [ORNL; Eckerman, Keith F [ORNL; McGinn, Wilson [ORNL; Meck, Dr. Robert A. [U.S. Nuclear Regulatory Commission

2012-01-01

359

Preliminary survey of separations technology applicable to the pretreatment of Hanford tank waste (1992--1993)  

SciTech Connect

The US Department of Energy has established the Tank Waste Remediation System (TWRS) to manage and dispose of radioactive wastes stored at the Hanford Site. Within this program are evaluations of pretreatment system alternatives through literature reviews. The information in this report was collected as part of this project at Pacific Northwest Laboratory. A preliminary survey of literature on separations recently entered into the Hanford electronic databases (1992--1993) that have the potential for pretreatment of Hanford tank waste was conducted. Separation processes that can assist in the removal of actinides (uranium, plutonium, americium), lanthanides, barium, {sup 137}Cs, {sup 90}Sr,{sup 129 }I, {sup 63}Ni, and {sup 99}Tc were evaluated. Separation processes of interest were identified through literature searches, journal reviews, and participation in separation technology conferences. This report contains brief descriptions of the potential separation processes, the extent and/or selectivity of the separation, the experimental conditions, and observations. Information was collected on both national and international separation studies to provide a global perspective on recent research efforts.

Lawrence, W.E.; Kurath, D.E.

1994-04-01

360

Separation science and technology  

SciTech Connect

The focus of this project is the demonstration and advancement of membrane-based separation and destruction technologies. The authors are exploring development of membrane systems for gas separations, selective metal ion recovery, and for separation or destruction of hazardous organics. They evaluated existing polymers and polymer formulations for recovery of toxic oxyanionic metals such as chromate and arsenate from selected waste streams and developed second-generation water-soluble polymeric systems for highly selective oxyanion removal and recovery. They optimized the simultaneous removal of radioactive strontium and cesium from aqueous solutions using the new nonhazardous separations agents, and developed recyclable, redox-active extractants that permitted recovery of the radioactive ions into a minimal waste volume. They produced hollow fibers and fabricated prototype hollow-fiber membrane modules for applications to gas separations and the liquid-liquid extraction and recovery of actinides and nuclear materials from process streams. They developed and fabricated cyclodextrin-based microporous materials that selectively absorb organic compounds in an aqueous environment; the resultant products gave pure water with organics at less than 0.05 parts per billion. They developed new, more efficient, membrane-based electrochemical reactors for use in organic destruction in process waste treatment. They addressed the need for advanced oxidation technologies based on molecular-level materials designs that selectively remove or destroy target species. They prepared and characterized surface-modified TiO{sub 2} thin films using different linking approaches to attach ruthenium photosensitizers, and they started the measurement of the photo-degradation products generated using surface modified TiO{sub 2} films in reaction with chlorophenol.

Smith, B.F.; Sauer, N.; Chamberlin, R.M.; Gottesfeld, S.; Mattes, B.R.; Li, D.Q.; Swanson, B.

1998-12-31

361

Extraction and spectrophotometric determination of uranium(VI)  

Microsoft Academic Search

A selective method for the solvent extraction and spectrophotometric determination of uranium(VI) is described. Uranium can be extracted into chloroform at pH 6.0 with N-m-chlorophenyl-2-theno-hydroxamic acid (N-m-CPTHA) and determined by spectrophotometry using 1-(2-pyridylazo)-2-naphthol (PAN). The molar absorptivity is 1.50·104 1·mol–1·cm–1 at 560 nm. The system obeys Beer's law within the range 0.95–20.00 ppm of uranium. Alternatively, a back-extraction procedure was

Y. K. Agrawal; V. J. Bhatt

1986-01-01

362

Properties of radio-frequency heated argon confined uranium plasmas  

NASA Technical Reports Server (NTRS)

Pure uranium hexafluoride (UF6) was injected into an argon confined, steady state, rf-heated plasma within a fused silica peripheral wall test chamber. Exploratory tests conducted using an 80 kW rf facility and different test chamber flow configurations permitted selection of the configuration demonstrating the best confinement characteristics and minimum uranium compound wall coating. The overall test results demonstrated applicable flow schemes and associated diagnostic techniques were developed for the fluid mechanical confinement and characterization of uranium within an rf plasma discharge when pure UF6 is injected for long test times into an argon-confined, high-temperature, high-pressure, rf-heated plasma.

1976-01-01

363

Experimental critical parameters of enriched uranium solution in annular tank geometries  

Microsoft Academic Search

A total of 61 critical configurations are reported for experiments involving various combinations of annular tanks into which enriched uranium solution was pumped. These experiments were performed at two widely separated times in the 1980s under two programs at the Rocky Flats Plant`s Critical Mass Laboratory. The uranyl nitrate solution contained about 370 g of uranium per liter, but this

1996-01-01

364

Method for the recovery of uranium values from uranium tetrafluoride  

DOEpatents

The invention is a novel method for the recovery of uranium from dry, particulate uranium tetrafluoride. In one aspect, the invention comprises reacting particulate uranium tetrafluoride and calcium oxide in the presence of gaseous oxygen to effect formation of the corresponding alkaline earth metal uranate and alkaline earth metal fluoride. The product uranate is highly soluble in various acidic solutions whereas the product fluoride is virtually insoluble therein. The product mixture of uranate and alkaline earth metal fluoride is contacted with a suitable acid to provide a uranium-containing solution, from which the uranium is recovered. The invention can achieve quantitative recovery of uranium in highly pure form.

Kreuzmann, A.B.

1982-10-27

365

Method for the recovery of uranium values from uranium tetrafluoride  

DOEpatents

The invention is a novel method for the recovery of uranium from dry, particulate uranium tetrafluoride. In one aspect, the invention comprises reacting particulate uranium tetrafluoride and calcium oxide in the presence of gaseous oxygen to effect formation of the corresponding alkaline earth metal uranate and alkaline earth metal fluoride. The product uranate is highly soluble in various acidic solutions wherein the product fluoride is virtually insoluble therein. The product mixture of uranate and alkaline earth metal fluoride is contacted with a suitable acid to provide a uranium-containing solution, from which the uranium is recovered. The invention can achieve quantitative recovery of uranium in highly pure form.

Kreuzmann, Alvin B. (Cincinnati, OH)

1983-01-01

366

Removal of fluoride and uranium by nanofiltration and reverse osmosis: A review.  

PubMed

Inorganic contamination in drinking water, especially fluoride and uranium, has been recognized as a worldwide problem imposing a serious threat to human health. Among several treatment technologies applied for fluoride and uranium removal, nanofiltration (NF) and reverse osmosis (RO) have been studied extensively and proven to offer satisfactory results with high selectivity. In this review, a comprehensive summary and critical analysis of previous NF and RO applications on fluoride and uranium removal is presented. Fluoride retention is generally governed by size exclusion and charge interaction, while uranium retention is strongly affected by the speciation of uranium and size exclusion usually plays a predominant role for all species. Adsorption on the membrane occurs as some uranium species interact with membrane functional groups. The influence of operating conditions (pressure, crossflow velocity), water quality (concentration, solution pH), solute-solute interactions, membrane characteristics and membrane fouling on fluoride and uranium retention is critically reviewed. PMID:25461935

Shen, Junjie; Schäfer, Andrea

2014-11-01

367

Laser system for isotope separation  

NASA Astrophysics Data System (ADS)

Atomic vapor laser isotope separation (AVLIS) is regarded as the most promising method to obtain srightly enriched economical nuclear fuel for a nuclear power plant. However, achieving a high power laser seems to be the bottle neck in its industrialization. In 1985, after successful development of high power lasers, the U.S. announced that AVLIS would be used for future methods of uranium enrichment. In Japan , Laser Atomic Separation Enrichment Research Associates of Japan (LASER-J), a joint Japanese utility companies research organization, was founded in April, 1987, to push a development program for laser uranium enrichment. Based on research results obtained from Japanese National Labs, and Universities , Laser-J is now constructing an AVLIS experimental facility at Tokai-mura. It is planned to have a 1-ton swu capacity per year in 1991. Previous to the experimental facility construction , Toshiba proceeded with the preliminary testing of an isotope separation system, under contract with Laser-J. Since the copper vapor laser (CVL) and the dye laser (DL) form a good combination , which can obtain high power tunable visible lights ,it is suitable to resonate uranium atoms. The laser system was built and was successfully operated in Toshiba for two years. The system consist of three copper vapor lasers , three dye lasers and appropriate o Atomic vapor laser isotope separation (AVLIS) is regarded as the most promising method to obtain srightly enriched economical nuclear fuel for a nuclear power plant. However, achieving a high power laser seems to be the bottle neck in its industrialization. In 1985, after successful development of high power lasers, the U.S. announced that AVLIS would be used for future methods of uranium enrichment. In Japan , Laser Atomic Separation Enrichment Research Associates of Japan (LASER-J) , a joint Japanese utility companies research organization , was founded in April, 1987, to push a development program for laser uranium enrichment. Based on research results obtained from Japanese National Labs, and Universities, Laser-J is now constructing an AVLIS experimental facility at Tokai-mura. It is planned to have a 1-ton swu capacity per year in 1991. Previous to the experimental facility construction, Toshiba proceeded with the preliminary testing of an isotope separation system, under contract with Laser-J. Since the copper vapor laser (CVL) and the dye laser (DL) form a good combination, which can obtain high power tunable visible lights, it is suitable to resonate uranium atoms. The laser system was built and was successfully operated in Toshiba for two years. The system consist of three copper vapor lasers, three dye lasers and appropriate optics. With pertinent electronics, the system total out put is 3 watts at 5 kHz repetition rate. For each CVL-DL laser set, the CVL output power was designed and operated at 20 watts and fed into DL to obtain 1 watt output. The CVL-DL sets provide three different wave lengths. Accurate wave mixing and laser pulse timing are also required during the experiment. Those laser systems, designed and manufactured in Toshiba, satisfactorily maintained a total operation time of 2000 hours during the past two years. Design work and operating experience for this laser system are described in this paper.

Shirayama, Shimpey; Mikatsura, Takefumi; Ueda, Hiroaki; Konagai, Chikara

1990-06-01

368

31 CFR 540.316 - Uranium enrichment.  

...2014-07-01 2014-07-01 false Uranium enrichment. 540.316 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium...

2014-07-01

369

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Uranium enrichment. 540.316 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium...

2011-07-01

370

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Uranium enrichment. 540.316 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium...

2013-07-01

371

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Uranium enrichment. 540.316 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium...

2012-07-01

372

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Uranium enrichment. 540.316 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium...

2010-07-01

373

Chemical Separations  

NSDL National Science Digital Library

This site contains complete notes in a PowerPoint-like presentation for a chemical separations course. It covers a wide variety of topics, including distillation, extraction, gas chromatography, liquid chromatograpy, chromatography theory, instrumentation, electrophoresis, field flow fractionation, and affinity chromatography. It covers these topics thoroughly using a clear, consistent, and simple presentation style. Links to major topics like GC, LC, and electrophoresis provide specific information about the theory, instrumentation, and practice related to these techniques. The site also contains many annimations illustrating important separation processes.

374

Chest wall thickness measurements for enriched uranium: an alternative approach.  

PubMed

The Human Monitoring Laboratory has developed a technique to determine the chest wall thickness of an individual using information from the spectrum produced by internally deposited radionuclides. The technique has been investigated both theoretically and practically using phoswich detectors and the Lawrence Livermore Torso Phantom. The phantom was used with lung sets containing homogeneously distributed 93% enriched uranium, 20% enriched uranium, natural uranium, and 241Am. It was found that a 3-cm chest wall thickness can be estimated to within 9% when measuring 93% enriched uranium. The technique does not work for the latter two radionuclides because of an insufficient separation in the photon energies and poor resolution of the phoswich detectors. The technique is only of value for activity levels well above the detection limit. PMID:8175366

Kramer, G H; Puscalau, M

1994-05-01

375

A comparative study of economical separation and aggregation properties of biologically capped and thiol functionalized gold nanoparticles: selecting the eco-friendly trojan horses for biological applications.  

PubMed

We are presenting facile bio-fabrication of extremely stable gold nanoparticles (GNPs) using medicinal plant Azadirachta indica (commonly called Neem) and its comparison with most commonly used glutathione (GSH) protected GNPs in terms of stability under physiological conditions, seperation using density gradient centrifugation and aggregation properties in the solution. There was dual peak at 536 and 662 nm indicating the presence of non-spherical GNPs including triangles, rods and hexagons in case of A. indica mediated GNPs unlike citrate stabilized GNPs which exhibited single sharp peak. Spherical GNPs were separated from the consortium of uniquely shaped nanoparticles bio-fabricated using A. indica leaf extract using sucrose density gradient centrifugation (SDGC).To comprehend the anti-agglomeration potentials of A. indica leaf mediated GNPs and GSH-GNPs under physiological conditions, flocculation parameters (FP) were calculated and found to be least for A. indica leaf mediated GNPs, indicating their exceptional stability. PMID:23603039

Pandey, Sunil; Thakur, Mukeshchand; Shah, Ritu; Oza, Goldie; Mewada, Ashmi; Sharon, Madhuri

2013-09-01

376

Remedial action plan for the inactive uranium processing site at Naturita, Colorado. Remedial action selection report: Attachment 2, geology report; Attachment 3, ground water hydrology report; Attachment 4, supplemental information  

SciTech Connect

The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the U.S. Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), 42 USC {section} 7901 et seq. Part of the UMTRCA requires that the U.S. Nuclear Regulatory Commission (NRC) concur with the DOE`s remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the U.S. Environmental Protection Agency (EPA). This RAP serves two purposes. First, it describes the activities that are proposed by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium processing site near Naturita, Colorado. Second, this RAP, upon concurrence and execution by the DOE, the state of Colorado, and the NRC, becomes Appendix B of the cooperative agreement between the DOE and the state of Colorado.

NONE

1998-03-01

377

Occurrence of Metastudtite (Uranium Peroxide Dihydrate) at a FUSRAP Site  

SciTech Connect

Uranium concentrations in groundwater in a localized area of a site exceed the USEPA Maximum Contaminant Level (MCL) by a factor of one thousand. Although the groundwater seepage velocity ranges up to 0.7 meters per day (m/day), data indicate that the uranium is not migrating in groundwater. We believe that the uranium is not mobile because of local geochemical conditions and the unstable nature of the uranium compound present at the site; uranium peroxide dihydrate (metastudtite). Metastudtite [UO{sub 4}.2(H{sub 2}O) or (U(O{sub 2})|O|(OH){sub 2}).3H{sub 2}O] has been identified at other sites as an alteration product in casks of spent nuclear fuel, but neither enriched nor depleted uranium were present at this site. Metastudtite was first identified as a natural mineral in 1983, although documented occurrences in the environment are uncommon. The U.S. Army Corps of Engineers (USACE) is conducting a remedial investigation at the DuPont Chambers Works in Deep water New Jersey under the Formerly Utilized Sites Remedial Action Program (FUSRAP) to evaluate radioactive contamination resulting from historical activities conducted in support of Manhattan Engineering District operations. From 1942 to 1947, Chambers Works converted uranium oxides to uranium tetrafluoride and uranium metal. More than half of the production at this facility resulted from the recovery process, where uranium-bearing dross and scrap were reacted with hydrogen peroxide to produce uranium peroxide dihydrate. The 280-hectare Chambers Works has produced some 600 products, including petrochemicals, aromatics, fluoro-chemicals, polymers, and elastomers. Contaminants resulting from these processes, including separate-phase petrochemicals, have also been detected within the boundaries of the FUSRAP investigation. USACE initiated remedial investigation field activities in 2002. The radionuclides of concern are natural uranium (U{sub nat}) and its short-lived progeny. Areas of impacted soil generally correspond to the footprints of the former production buildings. U{sub nat} concentrations in soil exceed the investigative screening value, 518 Becquerels per kilogram (Bq/kg) [14 pico-curies per gram (pCi/g)], to an approximate depth of 2.5 m. This depth corresponds to the depth of buried demolition debris from the uranium processing site. Aqueous-phase uranium has also been confirmed at the site and appears to coincide with uranium-impacted soils. Soil textures in the impacted area consist mainly of fine-grained silty sand and rubble. The hydraulic conductivities range from 5 E-6 to 1 E-5 m/s. Groundwater seepage velocity ranges from 0.003 m/day to 0.7 m/day in the impacted area. Groundwater investigations conducted throughout the FUSRAP site indicate that redox conditions in the shallow groundwater are reducing, with low dissolved oxygen concentrations, as would be expected underlying a petrochemical facility. In contrast, groundwater in the uranium source area is an oxidizing microenvironment, with elevated pH conditions, despite the presence of free-phase liquid hydrocarbons in close proximity. Dissolved oxygen is elevated in the uranium source area, which may be due to the presence of metastudtite. Metastudtite has been shown to produce hydrogen peroxide through the process of alpha irradiation of water molecules. Uranium peroxide dihydrate is more soluble in water than other hexavalent mineral forms. The literature suggests that in the absence of hydrogen peroxide, metastudtite is unstable in groundwater. Although the presence of metastudtite in the source area may have caused locally high levels of aqueous-phase uranium to form, the uranium ions may not be mobile outside of this small area because of significant abrupt changes in geochemical conditions. The ongoing groundwater investigation includes tasks to confirm the presence of metastudtite and hydrogen peroxide, and monitor for seasonal geochemical or hydrogeologic changes. (authors)

Young, C.M.; Nelson, K.A. [Cabrera Services, Inc., 103 East Mount Royal Avenue, Baltimore, MD 21202 (United States); Stevens, G.T.; Grassi, V.J. [US Army Corps of Engineers, Philadelphia District, 100 Penn Square East, Philadelphia, PA 19107-3390 (United States)

2006-07-01

378

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry.  

PubMed

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1-0.7 mug/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere. PMID:18964988

Kuroda, R; Kurosaki, M; Hayashibe, Y; Ishimaru, S

1990-06-01

379

Multiple recycle of REMIX fuel based on reprocessed uranium and plutonium mixture in thermal reactors  

SciTech Connect

REMIX fuel consumption in WWER-1000 is considered. REMIX fuel is fabricated from non-separated mixture of uranium and plutonium obtained during NPP spent fuel reprocessing with further makeup by enriched natural uranium. It makes possible to recycle several times the total amount of uranium and plutonium obtained from spent fuel with 100% loading of the WWER-1000 core. The stored SNF could be also involved in REMIX fuel cycle by enrichment of regenerated uranium. The same approach could be applied to closing the fuel cycle of CANDU reactors. (authors)

Fedorov, Y.S.; Bibichev, B.A.; Zilberman, B.Y. [RPA - V.G.Khlopin Radium Institute, St-Petersburg (Russian Federation); Baryshnikov, M.V.; Kryukov, O.V.; Khaperskaya, A.V. [State Corporation ROSATOM, Moscow (Russian Federation)

2013-07-01

380

Chromatographic Separations  

NSDL National Science Digital Library

This interactive applet provides a simulation of the separation of a mixture of 5 substances across a chromatographic column. The effect of changing various chromatographic factors can simultaneously be seen in the time-dependent dedistribution of analytes along the column along with the development of the chromatogram.

381

Process for electrolytically preparing uranium metal  

DOEpatents

A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

Haas, Paul A. (Knoxville, TN)

1989-01-01

382

Chemical Equilibrium of the Dissolved Uranium in Groundwaters From a Spanish Uranium-Ore Deposit  

SciTech Connect

The main objectives of this work are to determine the hydrogeochemical evolution of an uranium ore and identify the main water/rock interaction processes that control the dissolved uranium content. The Mina Fe uranium-ore deposit is the most important and biggest mine worked in Spain. Sageras area is located at the north part of the Mina Fe, over the same ore deposit. The uranium deposit was not mined in Sageras and was only perturbed by the exploration activities performed 20 years ago. The studied area is located 10 Km northeast of Ciudad Rodrigo (Salamanca) at an altitude over 650 m.a.s.l. The uranium mineralization is related to faults affecting the metasediments of the Upper Proterozoic to Lower Cambrian schist-graywacke complex (CEG), located in the Centro-Iberian Zone of the Hesperian Massif . The primary uranium minerals are uraninite and coffinite but numerous secondary uranium minerals have been formed as a result of the weathering processes: yellow gummite, autunite, meta-autunite, torbernite, saleeite, uranotile, ianthinite and uranopilite. The water flow at regional scale is controlled by the topography. Recharge takes place mainly in the surrounding mountains (Sierra Pena de Francia) and discharge at fluvial courses, mainly Agueda and Yeltes rivers, boundaries S-NW and NE of the area, respectively. Deep flows (lower than 100 m depth) should be upwards due to the river vicinity, with flow directions towards the W, NW or N. In Sageras-Mina Fe there are more than 100 boreholes drilled to investigate the mineral resources of the deposit. 35 boreholes were selected in order to analyze the chemical composition of groundwaters based on their depth and situation around the uranium ore. Groundwater samples come from 50 to 150 m depth. The waters are classified as calcium-bicarbonate type waters, with a redox potential that indicates they are slightly reduced (values vary between 50 to -350 mV). The TOC varies between <0.1 and 4.0 mgC/L and the dissolved uranium has a maximum value of 7.7 mg/L. According the analytical data of dissolved uranium, the mineral closest to equilibrium seems to be UO{sub 2}(am). The tritium contents in the groundwaters vary between 1.5 and 7.3 T.U. Considering that the mean value of tritium in rainwater from the studied area has a value of 4 T.U., it can be concluded that the residence times of the groundwaters are relatively short, not longer than 50 years in the oldest case. (authors)

Garralon, Antonio; Gomez, Paloma; Turrero, Maria Jesus; Buil, Belen; Sanchez, Lorenzo [Departamento de Medio Ambiente, CIEMAT, Avda. Complutense 22. Edificio 19, Madrid, 28040 (Spain)

2007-07-01

383

Influence of uranium hydride oxidation on uranium metal behaviour  

SciTech Connect

This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

Patel, N.; Hambley, D. [National Nuclear Laboratory (United Kingdom); Clarke, S.A. [Sellafield Ltd (United Kingdom); Simpson, K.

2013-07-01

384

The use of carbonate lixiviants to remove uranium from uranium-contaminated soils  

SciTech Connect

The objective of this research was to design an extraction media and procedure that would selectively remove uranium without adversely affecting the soils` physicochemical characteristics or generating secondary waste forms difficult to manage or dispose of. Investigations centered around determining the best lixivant and how the various factors such as pH, time, and temperature influenced extraction efficiency. Other factors investigated included the influence of attrition scrubbing, the effect of oxidants and reductants and the recycling of lixiviants. Experimental data obtained at the bench- and pilot-scale levels indicated 80 to 95% of the uranium could be removed from the uranium-contaminated soils by using a carbonate lixiviant. The best treatment was three successive extractions with 0.25 M carbonate-bicarbonate (in presence of KMnO{sub 4} as an oxidant) at 40 C followed with two water rinses.

Francis, C.W.; Lee, S.Y.; Wilson, J.H. [Oak Ridge National Lab., TN (United States); Timpson, M.E.; Elless, M.P. [Oak Ridge Inst. for Science and Education, TN (United States)

1997-08-01

385

Results of the Separations Area ground-water monitoring networks for 1986  

SciTech Connect

The Separations Area ground-water monitoring network consisted of 137 wells. Samples from wells in the monitoring network were collected on a monthly, quarterly, or semiannual schedule, depending on the history of the liquid waste disposal site. Samples were analyzed selectively for total alpha, total beta, tritium, /sup 90/Sr, /sup 137/Cs, /sup 60/Co, /sup 106/Ru, total uranium and nitrate. Average concentrations of contaminants in most wells were essentially the same in 1986 as in 1985. The DCG for tritium was exceeded at two PUREX cribs. The ACL specified for /sup 90/Sr was exceeded in three wells near the 216-A-25 Pond. Disposal of effluents to the pond decreased as the main pond was reduced in width to a ditch leading the overflow pond. The ACL guidelines for uranium were exceeded although concentrations were below the DCG; the source of this uranium is probably the inactive 216-B-12 crib. Uranium concentrations above the ACL but below the DCG were also observed at the 216-U-14 ditch and the source is under evaluation. The inactive 216-B-5 reverse well exceeded the DCG for /sup 90/Sr and the ACL for /sup 137/Cs and uranium. Inactive facilities exceeding Rockwell guidelines were the 216-S-1/2 cribs, 216-U-1/2 cribs, the 216-U-10 pond, and the 216-U-6 crib. The 216-S-1/2 cribs have historically had high /sup 137/Cs concentrations because of localized contamination but are below the DCG. Uranium concentrations, which are above the DCG, have stabilized at the 216-U-1/2 cribs after the remedial pumping and uranium removal conducted in 1985. Possible additional action is currently being evaluated. Disposal of the effluent from the ion exchange column to the 216-S-25 crib resulted in ground-water concentrations that exceeded Rockwell guidelines but below the DCG. Ground water near the 216-U-10 pond remains elevated but below the DCG due to past disposal to the pond, which was deactivated in 1984. 23 refs., 25 figs., 26 tabs.

Law, A.G.; Serkowski, J.A.; Schatz, A.L.

1987-07-01

386

The influence of the mobile phase pH and the stationary phase type on the selectivity tuning in high performance liquid chromatography nucleosides separation.  

PubMed

Analysis of the modified nucleosides is particularly important in the medical area because of a possibility of cancerogenic processes studies. The aim of this work was to study the selectivity tuning of modified nucleosides through the investigations of interactions analyte (modified nucleoside) <==> stationary phase <==> mobile phase. A series of homemade stationary phases with different surface properties has been utilized. All of them contain various interaction sites such as: cholesterol (SG-CHOL); n-acylamide (SG-CHOL, SG-AP); aminopropyl (SG-CHOL, SG-AP, SG-NH2, SG-MIX); cyanopropyl, phenyl, octyl (SG-MIX), octadecyl (SG-MIX, SG-C18) and silanols localized on the silica gel surface of all packings. The attempt to predict the main interactions responsible for the retention between nucleosides and stationary phase ligands was done on the basis of the elemental analysis, and proportional part of an individual ligand bonded to silica surface results. In order to study the influence of different packing types on the analyzed nucleosides retention, the relationship between pH of the mobile phase buffer and the selectivity of a stationary phase was investigated. PMID:16158992

Kowalska, Sylwia; Krupczy?ska, Katarzy?a; Buszewski, Bogus?aw

2005-08-01

387

Spectrophotometric determination of uranium with arsenazo-III in perchloric acid  

Microsoft Academic Search

A short, sensitive and reliable spectrophotometric method, which has advantages over all known “wet chemistry” methods for uranium determination with regard to tolerance to common interferences, has been developed for the determination of uranium. Selectivity, molar absorptivity and the determination range of uranium have been enhanced by using 0.07% arsenazo-III as a chromogenic reagent. The use of 3moldm?3 perchloric acid

Muhammad Haleem Khan; Peter Warwick; Nick Evans

2006-01-01

388

Optical separable wavelet transform  

NASA Astrophysics Data System (ADS)

Although Optical wavelet transform has some advantages over discrete wavelet transform, but the mother wavelets to used are very few. That limits the signal processing ability of optical wavelet transform. Without scaling functions, the multiresolution analysis of a mother wavelet is not complete. In this paper, almost all the mother wavelets used in discrete wavelet transform are introduced into optical wavelet transform. Based on the analysis, we find whether the mother wavelets have analytical forms is not a necessary condition for implementing them in optical wavelet transform. Optical wavelet transform only needs to obtain the 2D approximations of wavelet functions. Then, with the cascade algorithm, the 1D approximations of scaling and wavelet functions are computed. By the scheme of 2D separable wavelet transform, the approximations of 2D scaling and wavelet functions are constructed. So mother wavelets frequently utilized in discrete wavelet transform are introduced into optical wavelet transform. With the increase of mother wavelet for selection, it is natural to classify optical wavelet transform into separable and non-separable cases as it does in discrete wavelet transform. Since the mothers introduced by the method in this paper are separable, they are included in the separable optical wavelet transform. And the advantages of the separable mothers are listed with corresponding examples.

Cai, De; Tan, Qiaofeng; Yan, Yingbai; Jin, Guofan; He, Qingsheng

2004-11-01

389

Preparation of High Density Uranium Nitride and Uranium Carbonitride Fuel Pellets  

Microsoft Academic Search

Uranium nitride and uranium carbonitride fuel pellets were prepared for irradiation in the Japan Material Testing Reactor. The pellets are 6.9 mm in diameter and 7 mm long, and are of natural and 5% enriched uranium. Uranium nitride powder was prepared from uranium metal via hydride and higher nitride. Uranium carbide powder was prepared from uranium metal by hydriding and

Noboru Ol; Satoru HIRAYAMA; Isami TANABE; Akikazu MURAMATSU; Toshiyuki KAWADA

1972-01-01

390

6-(Tetrazol-5-yl)-2,2'-bipyridine: a highly selective ligand for the separation of lanthanides(III) and actinides(III).  

PubMed

The coordination structure in the solid state and solution complexation behavior of 6-(tetrazol-5-yl)-2,2'-bipyridine (HN4bipy) with samarium(III) was investigated as a model system for actinide(III)/lanthanide(III) separations. Two different solid 1:2 complexes, [Sm(N4bipy)2(OH)(H2O)2] (1) and [Sm(N4bipy)2(HCOO)(H2O)2] (2), were obtained from the reaction of samarium(III) nitrate with HN4bipy in isopropyl alcohol, resuspension in N,N-dimethylformamide (DMF), and slow crystallization. The formate anion coordinated to samarium in 2 is formed by decomposition of DMF to formic acid and dimethylamine. Time-resolved laser fluorescence spectroscopy (TRLFS) studies were performed with curium(III) and europium(III) by using HN4bipy as the ligand. Curium(III) is observed to form 1:2 and 1:3 complexes with increasing HN4bipy concentration; for europium(III), formation of 1:1 and 1:3 complexes is observed. Although the solid-state samarium complexes were confirmed as 1:2 species the 1:2 europium(III) solution complex in ethanol was not identified with TRLFS. The determined conditional stability constant for the 1:3 fully coordinated curium(III) complex species is more than 2 orders of magnitude higher than that for europium(III) (log ?3[Cm(N4bipy)3] = 13.8 and log ?3[Eu(N4bipy)3] = 11.1). The presence of added 2-bromodecanoic acid as a lipophilic anion source reduces the stability constant for formation of the 1:2 and 1:3 curium(III) complexes, but no ternary complexes were observed. The stability constants for the 1:3 metal ion-N4bipy complexes equate to a theoretical separation factor, SF(Cm(III)/Eu(III)) ? 500. However, the low solubility of the HN4bipy ligand in nonpolar solvents typically used in actinide-lanthanide liquid-liquid extractions prevents its use as a partitioning extractant until a more lipophilic HN4bipy-type ligand is developed. PMID:24967733

Kratsch, Jochen; Beele, Björn B; Koke, Carsten; Denecke, Melissa A; Geist, Andreas; Panak, Petra J; Roesky, Peter W

2014-09-01

391

Dissolution rates of uranium compounds in simulated lung fluid  

SciTech Connect

Maximum dissolution rates of uranium into simulated lung fluid from a variety of materials were measured at 37/sup 0/in the where f/sub i/ is in order to estimate clearance rates from the deep lung. A batch procedure was utilized in which samples containing as little as 10 ..mu..g of natural uranium could be tested. The materials included: products of uranium mining, milling and refining operations, coal fly ash, an environmental sample from a site exposed to multiple uranium sources, and purified samples of (NH/sub 4/)/sub 2/U/sub 2/O/sub 7/ U/sub 3/O/sub 8/, UO/sub 2/, and UF/sub 4/. Dissolution of uranium from several materials indicated the presence of more than one type of uranium compound; but in all cases, the fraction F of uranium remaining undissolved at any time t could be represented by the sum of up to three terms in the series: F = ..sigma../sub i/f/sub i/ exp (-0.693t/UPSILON/sub i/), where f/sub i/ is the initial fraction of component i with dissolution half-time epsilon/sub i/. Values of epsilon/sub i/ varied from 0.01 day to several thousand days depending on the physical and chemical form of the uranium. Dissolution occurred predominantly by formation of the (UO/sub 2/(CO/sub 3/)/sub 3/)/sup 4 -/ ion; and as a result, tetravalent uranium compounds dissolved slowly. Dissolution rates of size-separated yellow-cake aerosols were found to be more closely correlated with specific surface area than with aerodynamic diameter.

Kalkwarf, D.R.

1981-01-01

392

Pyrochemical separations technologies envisioned for the U. S. accelerator transmutation of waste system  

SciTech Connect

A program has been initiated for the purpose of developing the chemical separations technologies necessary to support a large Accelerator Transmutation of Waste (ATW) system capable of dealing with the projected inventory of spent fuel from the commercial nuclear power stations in the United States. The baseline process selected combines aqueous and pyrochemical processes to enable the efficient separation of uranium, technetium, iodine, and the transuranic elements from LWR spent fuel. The diversity of processing methods was chosen for both technical and economic factors. A six-year technology evaluation and development program is foreseen, by the end of which an informed decision can be made on proceeding with demonstration of the ATW system.

Laidler, J. J.

2000-02-17

393

Laser-isotope-separation technology. [Review; economics  

SciTech Connect

The Molecular Laser Isotope Separation (MLIS) process currently under development is discussed as an operative example of the use of lasers for material processing. The MLIS process, which uses infrared and ultraviolet lasers to process uranium hexafluoride (UF/sub 6/) resulting in enriched uranium fuel to be used in electrical-power-producing nuclear reactor, is reviewed. The economics of the MLIS enrichment process is compared with conventional enrichment technique, and the projected availability of MLIS enrichment capability is related to estimated demands for U.S. enrichment service. The lasers required in the Los Alamos MLIS program are discussed in detail, and their performance and operational characteristics are summarized. Finally, the timely development of low-cost, highly efficient ultraviolet and infrared lasers is shownd to be the critical element controlling the ultimate deployment of MLIS uranium enrichment. 8 figures, 7 tables.

Jensen, R.J.; Blair, L.S.

1981-01-01

394

Battery separator  

SciTech Connect

In an alkaline dry cell battery separator being a laid mat of non-dissolvable polyvinyl alcohol fibers held together by a matrix of dissolved or partially dissolved dissolvable polyvinyl alcohol fibers, an improvement is described comprising the mat having up to 85% of cellulosic fibers relatively uniformly distributed in and among the non-dissolvable polyvinyl alcohol fibers and held therein by the matrix.

La Bonte, R.J.

1988-08-30

395

Determination of ¹³?Cs and ¹³?Cs/¹³?Cs atomic ratio in environmental samples by combining ammonium molybdophosphate (AMP)-selective Cs adsorption and ion-exchange chromatographic separation to triple-quadrupole inductively coupled plasma-mass spectrometry.  

PubMed

Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011, the activity ratio of (134)Cs/(137)Cs has been widely used as a tracer for contamination source identification. However, because of the short half-life of (134)Cs (2.06 y), this tracer will become unavailable in the near future. This article presents an analytical method for the determination of the long-lived (135)Cs (t(2/1) = 2 × 10(6) y) and the atomic ratio of (135)Cs/(137)Cs, as a promising geochemical tracer, in environmental samples. The analytical method involves ammonium molybdophosphate (AMP)-selective adsorption of Cs and subsequent two-stage ion-exchange chromatographic separation, followed by detection of isolated radiocesium isotopes via triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-MS/MS). The AMP-selective adsorption of Cs and the chromatographic separation system showed high decontamination factors (10(4)-10(5)) for interfering elements, such as Ba, Mo, Sb, and Sn. Using ICP-MS/MS, only selected ions enter the collision/reaction cell to react with N2O, reducing the isobaric interferences ((135)Ba(+) and (137)Ba(+)) and polyatomic interferences ((95) Mo(40)Ar(+), (97) Mo(40)Ar(+), (119)Sn(16)O(+), and (121)Sb(16)O(+)) produced by sample matrix ions. The high abundance sensitivity (10(-9) for the (135)Cs/(133)Cs ratio) provided by ICP-MS/MS allowed reliable analysis of (135)Cs and (137)Cs isotopes with the lowest detection limits ever reported by mass counting methods (0.01 pg mL(-1) and 0.006 pg mL(-1), respectively). The developed analytical method was successfully applied to the determination of (135)Cs and (137)Cs isotopes in environmental samples (soil, litter, and lichen) collected after the FDNPP accident for contamination source identification. PMID:24931104

Zheng, Jian; Bu, Wenting; Tagami, Keiko; Shikamori, Yasuyuki; Nakano, Kazumi; Uchida, Shigeo; Ishii, Nobuyoshi

2014-07-15

396

SOME PROBLEMS OF RADIOMETRIC METHOD OF URANIUM ORE CONCENTRATION  

Microsoft Academic Search

The methods of determinirg the unevenness of uranium distribution in the ; pieces of ore and the means of utilizing the data obtained are discussed. ; Definite regularities in the radiometric method of concentration in connection ; with the questions of techaology and equipment are deduced in mathematical form. ; General characteristics of the main design units of radiometric separators

G. A. Kovda; M. L. Skrinichenko

1959-01-01

397

Analysis of enrichment factor of uranium enrichment by Redox chromatography  

Microsoft Academic Search

Experiments and computer simulation show that the uranium enrichment factor in redox chromatography is determined substantially be electron exchange, isotope adsorption-desorption, and oxidation state adsorption-desorption equilibria. Computer simulation utilizing the theoretical model closely predicts the difference between the value of an enrichment factor derived from the solution equilibrium and that observed in the chromatographic isotope separation, which is attributable to

T. Muyake; K. Takeda; H. Onitsuka; T. Watanabe

1986-01-01

398

Investigation of Great Basin big sagebrush and black greasewood as biogeochemical indicators of uranium mineralization. Final report. National Uranium Resource Evaluation  

SciTech Connect

The effects of varying phosphate concentrations in natural aqueous systems upon the uptake of uranium by big sagebrush (Artemesia tridentata subsp. tridentata) and black greasewood (Sarcobatus vermiculatus (Hook) Torr.) were investigated. Two separate growth experiments with five drip-flow hyroponic units were used and plant seedlings were grown for 60 days in solutions of varying phosphate and uranium concentrations. Successful growth experiments were obtained only for big sagebrush; black greasewood did not sustain sufficient growth. The phosphate concentration of the water did affect the uptake of uranium by the big sagebrush, and this effect is most pronounced in the region of higher concentrations of uranium in the water. The ratio of the concentration of uranium in the plant to that in the water was observed to decrease with increasing uranium concentration in solution. This is indicative of an absorption barrier in the plants. The field data shows that big sagebrush responds to uranium concentrations in the soil water and not the groundwater. The manifestation of these results is that the use of big sagebrush as a biogeochemical indicator of uranium is not recommended. Since the concentration of phosphate must also be knwon in the water supplying the uranium to the plant, one should analyze this natural aqueous phase as a hydrochemical indicator rather than the big sagebrush.

Diebold, F.E.; McGrath, S.

1982-11-01

399

Remotely operated facility for in situ solidification of fissile uranium  

SciTech Connect

A heavily shielded, remotely operated facility, located within the Radiochemical processing Plant at Oak Ridge National Laboratory (ORNL), has been designed and is being operated to convert approx.1000 kg of fissile uranium (containing approx.75% /sup 235/U, approx.10% /sup 233/U, and approx.140 ppM /sup 232/U) from a nitrate solution (130 g of uranium per L) to a solid oxide form. This project, the Consolidated Edison Uranium Solidification Program (CEUSP), is being carried out in order to prepare a stable uranium form for longterm storage. This paper describes the solidification process selected, the equipment and facilities required, the experimental work performed to ensure successful operation, some problems that were solved, and the initial operations.

McGinnis, C.P.; Collins, E.D.; Patton, B.D.

1986-01-01

400

Plasma core reactor simulations using RF uranium seeded argon discharges  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted using the United Technologies Research Center (UTRC) 80 kW and 1.2 MW RF induction heater systems to aid in developing the technology necessary for designing a self-critical fissioning uranium plasma core reactor (PCR). A nonfissioning, steady-state RF-heated argon plasma seeded with pure uranium hexafluoride (UF6) was used. An overall objective was to achieve maximum confinement of uranium vapor within the plasma while simultaneously minimizing the uranium compound wall deposition. Exploratory tests were conducted using the 80 kW RF induction heater with the test chamber at approximately atmospheric pressure and discharge power levels on the order of 10 kW. Four different test chamber flow configurations were tested to permit selection of the configuration offering the best confinement characteristics for subsequent tests at higher pressure and power in the 1.2 MW RF induction heater facility.

Roman, W. C.

1975-01-01

401

Gas separating  

DOEpatents

Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

Gollan, A.

1988-03-29

402

Gas separating  

DOEpatents

Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

Gollan, A.Z.

1990-12-25

403

Determination of (236)U and transuranium elements in depleted uranium ammunition by alpha-spectrometry and ICP-MS.  

PubMed

It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ((236)U, (239)Pu, (240)Pu, (241)Am, and (237)Np) in the ammunition. In this work the analysis of actinides by alpha-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. (242)Pu and (243)Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri- n-octylamine (TNOA), with a decontamination factor higher than 10(6); after elution plutonium was determined by ICP-MS ((239)Pu and (240)Pu) and alpha-spectrometry ((239+240)Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10(-12) g g(-1) and 2 x 10(-11) g g(-1). The (240)Pu/(239)Pu isotope ratio in one penetrator sample (0.12+/-0.04) was significantly lower than the (240)Pu/(239)Pu ratios found in two soil samples from Kosovo (0.35+/-0.10 and 0.27+/-0.07). (241)Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10(7). The concentration of (241)Am in the penetrator samples was 2.7 x 10(-14) g g(-1) and <9.4 x 10(-15) g g(-1). In addition (237)Np was detected at ultratrace levels. In general, ICP-MS and alpha-spectrometry results were in good agreement. The presence of anthropogenic radionuclides ((236)U, (239)Pu,(240)Pu, (241)Am, and (237)Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible. PMID:12458425

Desideri, D; Meli, M A; Roselli, C; Testa, C; Boulyga, S F; Becker, J S

2002-11-01

404

Separation of sodium-22 from irradiated targets  

DOEpatents

A process for selective separation of sodium-22 from an irradiated target including dissolving an irradiated target to form a first solution, contacting the first solution with hydrated antimony pentoxide to selectively separate sodium-22 from the first solution, separating the hydrated antimony pentoxide including the separated sodium-22 from the first solution, dissolving the hydrated antimony pentoxide including the separated sodium-22 in a mineral acid to form a second solution, and, separating the antimony from the sodium-22 in the second solution.

Taylor, Wayne A. (Los Alamos, NM); Jamriska, David (Los Alamos, NM)

1996-01-01

405

High loading uranium fuel plate  

DOEpatents

Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

Wiencek, Thomas C. (Bolingbrook, IL); Domagala, Robert F. (Indian Head Park, IL); Thresh, Henry R. (Palos Heights, IL)

1990-01-01

406

SPECTROPHOTOMETRIC DETERMINATION OF URANIUM WITH 1-(2-PYRIDYLAZO)-2- NAPHTHOL  

Microsoft Academic Search

From 40 to 400 gamma of uranium can be determined by extraction of ; uranyl nitrate into a tributyl phosphatechloroform solvent and subsequent color ; development in the organic extract with 1-(2-pyridylazo)-2-naphthol (PAN) in the ; presence of pyridine. The disodium salt of (ethylenedinitrilo)tetraacetic acid ; increased the selectivity of uranium extraction by chelating zirconium, bismuth, ; and manganese(II). Thorium

H. H. Gill; R. F. Rolf; G. W. Armstrong

1958-01-01

407

SPECTROPHOTOMETRIC DETERMINATION OF THE MICROAMOUNTS OF URANIUM PREVIOUSLY EXTRACTED WITH METHYL ISOBUTYL KETONE-TRIBUTYL PHOSPHATE  

Microsoft Academic Search

Selective extraction of uranium in nitric acid medium with a mixture of ; TBP-methylisobutylketone (1: 10) was achieved. Aluminum nitrate was used as ; salting agent. Complexing agents were added in order to avoid extraction of ; impurities. Extraction conditions were studied so that extraction was almost ; practically complete in a single run. Uranium was determined by colorimetry ;

J. V. Palomino; F. P. Delgado; J. Petrement; R. F. Cellini

1963-01-01

408

Biosorption of uranium and lead by Streptomyces longwoodensis  

SciTech Connect

Biosorption of uranium and lead by lyophilized cells of Streptomyces longwoodensis was examined as a function of metal concentration, pH, cell concentration, and culture age. Cells harvested from the stationary growth phase exhibited an exceptionally high capacity for uranium (0.44 g U/g dry weight) at pH 5. Calculated values of the distribution coefficient and separation factor indicated a strong preference of the cell mass for uranyl ions over lead ions. The specific uranium uptake was similar for the cell wall and the cytoplasmic fraction. Uranium uptake was associated with an increase in hydrogen ion concentration, and phosphorus analysis of whole cells indicated a simple stoichiometric ratio between uranium uptake and phosphorus content. It is proposed that metal ions are bound to phosphodiester residues present both in the cell wall and cytoplasmic fractions. Based on this model, it was shown that uranium accumulation exhibits a maximum at pH 4.6 that is supported by experimental data from previous investigations.

Friis, N.; Myers-Keith, P.

1986-01-01

409

Anion-exchange enrichment and spectrophotometric determination of uranium in sea-water.  

PubMed

A method is proposed for the determination of uranium in sea-water. The uranium is strongly sorbed on a strongly basic anion-exchange resin (Cl(-) form) from acidified sea-water containing sodium azide (0.3M) and is easily eluted with 1M hydrochloric acid. Uranium in the effluent can be determined spectrophotometrically with Arsenazo III. The combined method allows easy and selective determination of uranium in sea-water without using a sophisticated adsorbent. The overall recovery and precision are satisfactory at the 3 mug/1. level. PMID:18964330

Kuroda, R; Oguma, K; Mukai, N; Iwamoto, M

1987-04-01

410

Maintaining the Uranium Resource Assessment Data System and assessing the 1992 US uranium potential resources. Final report  

SciTech Connect

For 1992, estimates of US undiscovered uranium resources were generated using revised economic index values (current to December 1992) in the Uranium Resources Assessment Data (URAD) System`s cost model. The endowments associated with the Estimated Additional Resources (EAR) and Speculative Resources (SR) values for all regions are unchanged from the 1991 values. Although higher 1992 indexes resulted in increased costs, the mean values for the $30-, $50-, and $ 100-per pound U308 forward-cost EAR category resources for 1992 show no significant changes when compared to the values in 1991. The mean values for the $30-, $50-, and $100-per pound U{sub 3}O{sub 8} forward-cost SR forward-cost category show decreases of 4, 3, and 1 percent, in the three categories respectively. Under the Memorandum of Understanding (MOU) between the Energy Information Administration (EIA), US Department of Energy, and the US Geological Survey (USGS), US Department of the Interior, the USGS develops estimates of uranium endowment for selected geological environments in the United States. New estimates of endowment are used to update the URAD System that is maintained for the EIA by the USGS. Endowment estimates were added for the solution-collapse breccia pipe uranium deposits in the Grand Canyon region in 1989 and for young surficial uranium deposits in the Flodelle Creek area in Washington in 1991. Estimates of uranium endowment for roll-front uranium deposits in northwestern Nebraska and adjacent states are nearly completed and will be added in 1994. Assessment of undiscovered uranium endowment in new areas by the USGS will be discontinued in FY 1995 due to phasing out of the uranium resources program in FY 1994. Improvements to the URAD System included automating the procedures necessary to generate the assessment reports. Data retrieval from the URAD System can now be performed using dBase IV version 1.5 data base management system.

Finch, W.I.; Grundy, W.D.; Pierson, C.T.; Kork, J.O.

1993-12-31

411

Uranium from seawater  

SciTech Connect

A novel process for recovering uranium from seawater is proposed and some of the critical technical parameters are evaluated. The process, in summary, consists of two different options for contacting adsorbant pellets with seawater without pumping the seawater. It is expected that this will reduce the mass handling requirements, compared to pumped seawater systems, by a factor of approximately 10/sup 5/, which should also result in a large reduction in initial capital investment. Activated carbon, possibly in combination with a small amount of dissolved titanium hydroxide, is expected to be the preferred adsorbant material instead of the commonly assumed titanium hydroxide alone. The activated carbon, after exposure to seawater, can be stripped of uranium with an appropriate eluant (probably an acid) or can be burned for its heating value (possible in a power plant) leaving the uranium further enriched in its ash. The uranium, representing about 1% of the ash, is then a rich ore and would be recovered in a conventional manner. Experimental results have indicated that activated carbon, acting alone, is not adequately effective in adsorbing the uranium from seawater. We measured partition coefficients (concentration ratios) of approximately 10/sup 3/ in seawater instead of the reported values of 10/sup 5/. However, preliminary tests carried out in fresh water show considerable promise for an extraction system that uses a combination of dissolved titanium hydroxide (in minute amounts) which forms an insoluble compound with the uranyl ion, and the insoluble compound then being sorbed out on activated carbon. Such a system showed partition coefficients in excess of 10/sup 5/ in fresh water. However, the system was not tested in seawater.

Gregg, D.; Folkendt, M.

1982-09-21

412

Separation of Technetium from Uranium and Waste Form Synthesis  

Microsoft Academic Search

In this project, systematic investigations on the Tc-Zr binary metal system will be evaluated for the first time. The synthesis of metallic Tc as well as its alloys with Zr will be evaluated. In order to provide valuable data to AFC R&D, the thermodynamic equilibrium phases, as well as their performance under repository conditions, will be examined.\\u000aThe research objectives

Kenneth Czerwinski

2008-01-01

413

Separation of Technetium from Uranium and Waste Form Synthesis  

Microsoft Academic Search

In this project, systematic investigations on the Tc-Zr binary metal system will be evaluated for the first time. The synthesis of metallic Tc as well as its alloys with Zr will be evaluated. In order to provide valuable data to AFC R&D, the thermodynamic equilibrium phases, as well as their performance under repository conditions, will be examined.

Kenneth Czerwinski

2007-01-01

414

Fluid-bed fluoride volatility process recovers uranium from spent uranium alloy fuels  

NASA Technical Reports Server (NTRS)

Fluid-bed fluoride volatility process recovers uranium from uranium fuels containing either zirconium or aluminum. The uranium is recovered as uranium hexafluoride. The process requires few operations in simple, compact equipment, and eliminates aqueous radioactive wastes.

Barghusen, J. J.; Chilenskas, A. A.; Gunderson, G. E.; Holmes, J. T.; Jonke, A. A.; Kincinas, J. E.; Levitz, N. M.; Potts, G. L.; Ramaswami, D.; Stethers, H.; Turner, K. S.

1967-01-01

415

Two-dimensional peptide separation improving sensitivity of selected reaction monitoring-based quantitative proteomics in mouse liver tissue: comparing off-gel electrophoresis and strong cation exchange chromatography.  

PubMed

Protein expression analysis is one of the most powerful tools to further the understanding of biological systems. Progress in the field of mass spectrometry has shifted focus from gel-based approaches to the upcoming LC-selected reaction monitoring (SRM) technique which combines high technical accuracy with absolute quantification of proteins and the capability for high-throughput analyses. Due to these properties, LC-SRM has the potential to become the foundation for biomarker analysis, targeted hypothesis driven proteomic studies and contribute to the field of systems biology. While the performance of LC-SRM applied to samples from various bodily fluids, particularly plasma, and microorganisms has been extensively investigated, there is only little experience with its application to animal tissue samples. Here, we show that a conventional one-dimensional LC-SRM workflow applied to mouse liver tissue suffers from a shortcoming in terms of sensitivity for lower abundance proteins. This problem could be solved through the extension of the standard workflow by an additional dimension of separation at the peptide level prior to online LC-SRM. For this purpose, we used off-gel electrophoresis (OGE) which is also shown to outperform strong cation exchange (SCX) in terms of resolution, gain of signal intensity, and predictability of separation. The extension of the SRM workflow by a high resolving peptide separation technique is an ideal combination as it allows the addition of stable isotope standards directly after trytic digestion and will increase the dynamic range of protein abundances amenable by SRM in animal tissue. PMID:22994301

Schäfer, Alexander; von Toerne, Christine; Becker, Silke; Sarioglu, Hakan; Neschen, Susanne; Kahle, Melanie; Hauck, Stefanie M; Ueffing, Marius

2012-10-16

416

Chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade uranium dioxide powders and pellets  

SciTech Connect

Uranium dioxide is used as a nuclear-reactor fuel. In order to be suitable for this purpose, the material must meet certain criteria for uranium content, stoichiometry, isotopic composition, impurity content. The following analytical procedures, which are described in detail, are designed to show whether or not a given material meets specifications: uranium by ferrous sulfate reduction in phosphoric acid and dichromate titration method; uranium and oxygen uranium atomic ratio by the ignition (gravimetric) impurity correction method; oxygen to uranium atomic ratios by the polarographic method; carbon (total) by direct combustion-thermal conductivity method; total chlorine and fluorine by pyrohydrolysis ion-selective electrode method; moisture by the coulometric, electrolytic moisture analyzer method; nitrogen by the Kjeldahl method; total sulfur by distillation-spectrophotometric method; isotopic uranium composition by multiple-filament surface-ionization mass spectrometric method; spectrochemical determination of trace elements in high-purity uranium dioxide; volatile fluoride impurities by spectrochemical method using the rotating-disk spark technique; spectrochemical determination of silver by gallium oxide carrier D-C arc technique; rare earths by copper spark-spectrochemical method; impurity elements by a spark-source mass spectrographic method; surface area by nitrogen absorption method; total gas in reactor-grade uranium dioxide pellets; thorium and rare earth elements by spectroscopy; hydrogen by inert gas fusion; and uranium isotopic analysis by mass spectrometry. (JMT)

Not Available

1981-01-01

417

Spectrophotometric determination of uranium using dibenzoylmethane  

SciTech Connect

A procedure for the spectrophotometric determination of uranium has been developed in support of minerals research being conducted by the Bureau of Mines. Uranium is separated from the sample by tributylphosphate extraction from acid solution containing added aluminum nitrate and (ethylene dinitrilo)-tetraacetic acid solutions. The colored uranium-dibenzoylmethane complex is developed in the organic phase by adding an ethanol solution of dibenzoylmethane buffered with triethanolamine. Absorbance is measured at 410 nanometers, and the response is linear up to at least 100 micrograms U/sub 3/O/sub 8/ in the aqueous aliquot taken for analysis. Aliquots containing as little as 8 micrograms U/sub 3/O/sub 8/ may be analyzed with relative errors no greater than +-5%. For aliquots containing at least 35 micrograms U/sub 3/O/sub 8/, relative standard deviation at the 95% confidence level is about +-2.2%. Appropriate procedures are given for analyzing a wide variety of samples.

Jones, M.M.; MacDuff, J.S.; Whitehead, A.B.

1980-01-01

418

United States Transuranium and Uranium Registries  

SciTech Connect

The United States Transuranium and Uranium Registries are unique human tissue research programs studying the distribution, dose, and possible biological effects of the actinide elements in man, with the primary goal of assuring the adequacy of radiation protection standards for these radionuclides. The Registries research is based on radiochemical analysis of tissues collected at autopsy from voluntary donors who have documented occupational exposure to the actinides. To date, tissues, or in some cases radioanalytical results only, have been obtained from approximately 300 individuals; another 464 living individuals have volunteered to participate in the Registries research programs and have signed premortem informed consent and autopsy permissions. The Registries originated at the National Plutonium Registry which was started in 1968 as a then Atomic Energy Commission project under the aegis of a prime contractor at the Hanford site. In 1970, the name was changed to the United States Transuranium Registry to reflect a broader involvement with the higher actinides. In 1978, an administratively separate parallel registry, the United States Uranium Registry, was formed to carry out similar studies among uranium fuel cycle workers.

Kathren, R.

1993-02-28

419

Method of preparation of uranium nitride  

DOEpatents

Method for producing terminal uranium nitride complexes comprising providing a suitable starting material comprising uranium; oxidizing the starting material with a suitable oxidant to produce one or more uranium(IV)-azide complexes; and, sufficiently irradiating the uranium(IV)-azide complexes to produce the terminal uranium nitride complexes.

Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

2013-07-09

420

Controlling uranium reactivity March 18, 2008  

E-print Network

March 2008 Controlling uranium reactivity March 18, 2008 Uranium is an often misunderstood metal uranium research. In reality, uranium presents a wealth of possibilities for funda- mental chemistry. Many research groups have been involved in utilizing the large size and unique reactivity of the uranium atom

Meyer, Karsten

421

Microstructure of depleted uranium under uniaxial strain conditions  

SciTech Connect

Uranium samples of two different purities were used for spall strength measurements. Samples of depleted uranium were taken from very high purity material (38 ppM carbon) and from material containing 280 ppM C. Experimental conditions were chosen to effectively arrest the microstructural damage at two places in the development to full spall separation. Samples were soft recovered and characterized with respect to the microstructure and the form of damage. This allowed determination of the dependence of spall mechanisms on stress level, stress state, and sample purity. This information is used in developing a model to predict the mode of fracture.

Zurek, A.K.; Embury, J.D.; Kelly, A.; Thissell, W.R.; Gustavsen, R.L.; Vorthman, J.E.; Hixson, R.H.

1997-09-01

422

Failure mechanisms for compacted uranium oxide fuel cores  

SciTech Connect

Tension, compression, and shear tests were performed on test specimens of aluminum-clad, compacted powder fuel cores to determine failure mechanisms of the core material. The core, which consists of 70% uranium oxide in an aluminum matrix, frequently fails during post-extrusion drawing. Tests were conducted to various strain levels up to failure of the core. Sections were made of tested specimens to microscopically study initiation of failure. Two failure modes wee observed. Tensile failure mode is initiated by prior tensile failure of uranium oxide particles with the separation path strongly influenced by the arrangement of particles. Delamination mode consists of the separation of laminae formed during extrusion of tubes. Separation proceeds from fine cracks formed parallel to the laminae. Tensile failure mode was experienced in tension and shear tests. Delamination mode was produced in compression tests.

Berghaus, D.G.; Peacock, H.B.

1980-01-01

423

Oil separator  

SciTech Connect

This patent describes an oil separator for a horizontal screw compressor: a generally cylindrical member having a closed first end and having a second end having an opening therein for receiving the rotor assembly of a screw compressor; baffle seal means spaced from the closed first end and defining therewith a first chamber; generally horizontal divider plate means extending between the baffle seal means and the second end so as to divide the generally cylindrical member to thereby define second and third chambers with the second chamber being beneath and larger than the third chamber; the opening in the second end communicates with the second chamber whereby the second chamber is adapted to receive the rotor assembly; discharge deflector means in the second chamber for directing compressor discharge upwardly so as to impinge upon the divider plate means and deposit entrained oil thereon; demister means in the second chamber and coacting with the baffle seal means whereby compressor discharge must pass through the demister means to reach the first chamber.

Calupca, G.A.; Crone, L.L.; Maxey, W. III; Rubenic, E.K.

1988-12-06

424

Sexual Selection in Plants?Sexual Selection in Plants? HistoryHistory  

E-print Network

.Darwin's view. Separate from natural selection to explainSeparate from natural selection to explain exaggeratedIs there a trade--off with natural selection?off with natural selection? StylarStylar selection.selection. DoesSexual Selection in Plants?Sexual Selection in Plants? HistoryHistory Plant MatingPlant Mating

Cruzan, Mitchell B.

425

Sampling Plan for Assaying Plates Containing Depleted or Normal Uranium  

SciTech Connect

This paper describes the rationale behind the proposed method for selecting a 'representative' sample of uranium metal plates, portions of which will be destructively assayed at the Y-12 Security Complex. The total inventory of plates is segregated into two populations, one for Material Type 10 (depleted uranium (DU)) and one for Material Type 81 (normal [or natural] uranium (NU)). The plates within each population are further stratified by common dimensions. A spreadsheet gives the collective mass of uranium element (and isotope for DU) and the piece count of all plates within each stratum. These data are summarized in Table 1. All plates are 100% uranium metal, and all but approximately 60% of the NU plates have Kel-F{reg_sign} coating. The book inventory gives an overall U-235 isotopic percentage of 0.22% for the DU plates, ranging from 0.19% to 0.22%. The U-235 ratio of the NU plates is assumed to be 0.71%. As shown in Table 1, the vast majority of the plates are comprised of depleted uranium, so most of the plates will be sampled from the DU population.

Ivan R. Thomas

2011-11-01

426

Method for fabricating uranium foils and uranium alloy foils  

DOEpatents

A method of producing thin foils of uranium or an alloy. The uranium or alloy is cast as a plate or sheet having a thickness less than about 5 mm and thereafter cold rolled in one or more passes at substantially ambient temperatures until the uranium or alloy thereof is in the shape of a foil having a thickness less than about 1.0 mm. The uranium alloy includes one or more of Zr, Nb, Mo, Cr, Fe, Si, Ni, Cu or Al.

Hofman, Gerard L. (Downers Grove, IL); Meyer, Mitchell K. (Idaho Falls, ID); Knighton, Gaven C. (Moore, ID); Clark, Curtis R. (Idaho Falls, ID)

2006-09-05

427

The importance of colloids and mires for the transport of uranium isotopes through the Kalix River watershed and Baltic Sea  

NASA Astrophysics Data System (ADS)

The importance of colloids and organic deposits for the transport of uranium isotopes from continental source regions and through the estuarine environment was investigated in the mire-rich Kalix River drainage basin in northern Sweden and the Baltic Sea. Ultrafiltration techniques were used to separate uranium and other elements associated with colloids > 10 kD and >3 kD from "solute" uranium and provided consistent results and high recovery rates for uranium as well as for other elements from large volume samples. Uranium concentrations in 0.45 ?m-filtered Kalix River water samples increased by a factor of 3 from near the headwaters in the Caledonides to the river mouth while major cation concentrations were relatively constant. 234U/238U ratios were high ( ?234U = 770-1500) throughout the basin, without showing any simple pattern, and required a supply of 234U-rich water. Throughout the Kalix River, a large fraction (30-90%) of the uranium is carried by >10 kD colloids, which is compatible with uranium complexation with humic acids. No isotopic differences were found between colloid-associated and solute uranium. Within the Baltic Sea, about half of the uranium is removed at low salinities. The proportion that is lost is equivalent to that of river-derived colloid-bound uranium, suggesting that while solute uranium behaves conservatively during estuarine mixing, colloid-bound uranium is lost due to rapid flocculation of colloidal material. The association of uranium with colloids therefore may be an important parameter in determining uranium estuarine behavior. Mire peats in the Kalix River highly concentrate uranium and are potentially a significant source of recoil 234U to the mirewaters and river waters. However, mirewater data clearly demonstrate that only small 234U/238U shifts are generated relative to inflowing groundwater. A simple box model of uranium accumulation in peat and transport through the mire that is compatible with the mire data demonstrates that with efficient removal of uranium from solution, only small shifts in 234U/238U ratios can be generated in mirewater uranium. The measurements and model calculations show that mirewaters are not the primary source of the uranium in the river. Bedrock groundwaters with high 234U/238U ratios and uranium concentrations must be the dominant source of riverine uranium.

Porcelli, D.; Andersson, P. S.; Wasserburg, G. J.; Ingri, J.; Baskaran, M.

1997-10-01

428

Determination of Plutonium Isotope Ratios at Very Low Levels by ICP-MS using On-Line Electrochemically Modulated Separations  

SciTech Connect

Electrochemically modulated separations (EMS) are shown to be a rapid and selective means of extracting and concentrating Pu from complex solutions prior to isotopic analysis by inductively coupled plasma mass spectrometry (ICP?MS). This separation is performed in a flow injection mode, on?line with the ICP?MS. A three?electrode, flow?by electrochemical cell is used to accumulate Pu at an anodized glassy carbon electrode by redox conversion of Pu(III) to Pu (IV&VI). The entire process takes place in 2% v/v (0.46M) HNO3. No redox chemicals or acid concentration changes are required. Plutonium accumulation and release is redox dependent and controlled by the applied cell potential. Thus large transient volumetric concentration enhancements can be achieved. Based on more negative U(IV) potentials relative to Pu(IV), separation of Pu from uranium is efficient, thereby eliminating uranium hydride interferences. EMS?ICP?MS isotope ratio measurement performance will be presented for femtogram to attogram level plutonium concentrations.

Liezers, Martin; Lehn, Scott A.; Olsen, Khris B.; Farmer, Orville T.; Duckworth, Douglas C.

2009-10-01

429

Uranium prospecting method  

SciTech Connect

A technique of applying the thermoluminescence phenomenon to uranium prospecting. The thermoluminescence of specimens of quartz isolated from field samples is measured. The samples are then irradiated at several levels, and the thermoluminescence of the samples is measured at the various levels. This enables a determination of the natural radiation received by the samples the current radiation from the samples is measured with a dosimeter, and by using both shielded and unshielded dosimeters the type of radiation from the samples can be determined. Knowledge of the total natural radiation received by a sample and the current rate of radioactivity allows the determination of the present position of uranium or other radioactive source and its geological ''migration'' path.

Cabbiness, D.K.; Carel, A.B.; Leslie, W.D.

1981-05-12

430