The Hexagon, Volume 93, Number 3, Fall 2002

The Hexagon, Volume 93, Number 3, Fall 2002

Date: Autumn 2002
Creator: Alpha Chi Sigma
Description: Quarterly publication of the Alpha Chi Sigma chemistry fraternity containing articles related to chemistry research and the activities of the organization, including local chapters and groups.
Contributing Partner: UNT Libraries
Rediscovery of the Elements: Strontium

Rediscovery of the Elements: Strontium

Date: Autumn 2002
Creator: Marshall, James L., 1940- & Marshall, Virginia R.
Description: Article describing the history of the element strontium from its discovery in Strontian, Scotland, to its early uses in English medicine. Maps with directions and photographs of pertinent locations are included.
Contributing Partner: UNT College of Arts and Sciences
PROTON-CONDUCTING DENSE CERAMIC MEMBRANES FOR HYDROGEN SEPARATION

PROTON-CONDUCTING DENSE CERAMIC MEMBRANES FOR HYDROGEN SEPARATION

Date: December 1, 2002
Creator: Lin, Jerry Y.S.
Description: This project is aimed at preparation of thin membranes of a modified strontium ceramic material on porous substrates with improved hydrogen permeance. The research work conducted in this reporting period was focused on studying synthesis methods for preparation of thin thulium doped strontium cerate (SrCe{sub 0.95}Tm{sub 0.05}O{sub 3}, SCTm) membranes. The following two methods were studied in the past year: (1) polymeric-gel casting and (2) dry-pressing. The polymeric-gel casting method includes preparation of mixed metal oxide gel and coating of the gel on a macroporous alumina support. Micrometer thick SCTm films of the perovskite structure can be obtained by this method. However, the deposited films are not hermetic and it may require about 50 coatings in order to obtain gas-tight SCTm films by this method. Asymmetric SCTm membranes consisting of a thick macroporous SCTm support and a thin SCTm layer can be effectively prepared by the dry-pressing method. The membranes were prepared by pressing together a thick layer of coarse SCTm powder and a thin layer of finer SCTm powder, followed by calcination and sintering under proper conditions. The asymmetric SCTm membranes have desired phase structure and are hermetic. Hydrogen permeation flux through the SCT membranes is inversely proportional to ...
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Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors

Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors

Date: August 6, 2003
Creator: Wendt, Jost O. L.; Kerstein, Alan R.; Scheeline, Alexander; Pearlstein, Arne & Linak, William
Description: The Overall project demonstrated that toxic metals (cesium Cs and strontium Sr) in aqueous and organic wastes can be isolated from the environment through reaction with kaolinite based sorbent substrates in high temperature reactor environments. In addition, a state-of-the art laser diagnostic tool to measure droplet characteristic in practical 'dirty' laboratory environments was developed, and was featured on the cover of a recent edition of the scientific journal ''applied Spectroscopy''. Furthermore, great strides have been made in developing a theoretical model that has the potential to allow prediction of the position and life history of every particle of waste in a high temperature, turbulent flow field, a very challenging problem involving as it does, the fundamentals of two phase turbulence and of particle drag physics.
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Enhancement of methane conversion using electric fields. Quarterly report, July--September 1995

Enhancement of methane conversion using electric fields. Quarterly report, July--September 1995

Date: November 1, 1995
Creator: Mallinson, R.G. & Lobban, L.L.
Description: The goal of this project is the development of novel, economical, processes for the conversion of natural gas to more valuable projects such as methanol, ethylene and other organic oxygenates or higher hydrocarbons. The methodologies of the project are to investigate and develop low temperature electric discharges and electric field-enhanced catalysis for carrying out these conversions. In the case of low temperature discharges, the conversion is carried out at ambient temperature which in effect trades high temperature thermal energy for electric energy as the driving force for conversion. The low operating temperatures relax the thermodynamic constraints on the product distribution found at high temperature and also removes the requirements of large thermal masses required for current technologies. With the electric field-enhanced conversion, the operating temperatures are expected to be below those currently required for such processes as oxidative coupling, thereby allowing for a higher degree of catalytic selectivity while maintaining high activity.
Contributing Partner: UNT Libraries Government Documents Department
Environmental monitoring plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

Environmental monitoring plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

Date: September 1, 1995
Creator: unknown
Description: This document presents an Environmental Monitoring Plan (EMP) for Waste Area Grouping (WAG 6) at Oak Ridge National Laboratory (ORNL). This document updates a draft monitoring plan developed in 1993. The draft plan was never finalized awaiting resolution of the mechanisms for addressing RCRA concerns at a site where the CERCLA process resulted in a decision to defer action, i.e., postpone closure indefinitely. Over the past two years the Tennessee Department of Environment and Conservation (TDEC), US Department of Energy (DOE), and US Environmental Protection Agency (EPA) Region IV, have agreed that RCRA authority at the site will be maintained through a post- closure permit; ``closure`` in this case referring to deferred action. Both a Revised Closure Plan (DOE 1995a) and a Post-Closure Permit Application (DOE 1995b) have been developed to document this agreement; relevant portions of the EMP will be included in the RCRA Post-Closure Permit Application. As the RCRA issues were being negotiated, DOE initiated monitoring at WAG 6. The purpose of the monitoring activities was to (1) continue to comply with RCRA groundwater quality assessment requirements, (2) install new monitoring equipment, and (3) establish the baseline conditions at WAG 6 against which changes in contaminant releases could ...
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Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

Date: December 31, 1994
Creator: Bartsch, R.A.
Description: During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent ...
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Microbial Mineral Transformations at the Fe(II)/Fe(III) Redox Boundary for Solid Phase Capture of Strontium and Other Metal/Radionuclide Contaminants

Microbial Mineral Transformations at the Fe(II)/Fe(III) Redox Boundary for Solid Phase Capture of Strontium and Other Metal/Radionuclide Contaminants

Date: January 31, 2000
Creator: Ferris, F. G. & Roden, E. E.
Description: The migration of {sup 90}Sr in groundwater is a significant environmental concern at former nuclear weapons production sites in the US and abroad. Although retardation of {sup 90}Sr transport relative to mean groundwater velocity is known to occur in contaminated aquifers, Sr{sup 2+} does not sorb as strongly to iron oxides and other mineral phases as do other metal-radionuclides contaminants. Thus, some potential exists for extensive {sup 90}Sr migration from sources of contamination. Chemical or biological processes capable of retarding or immobilizing Sr{sup 2+} in groundwater environments are of interest from the standpoint of understanding controls on subsurface Sr{sup 2+} migration. In addition, it may be possible to exploit such processes for remediation of subsurface Sr contamination. In this study the authors examined the potential for the solid phase sorption and incorporation of Sr{sup 2+} into carbonate minerals formed during microbial Fe(III) oxide reduction as a first step toward evaluating whether this process could be used to promote retardation of {sup 90}Sr migrations in anaerobic subsurface environments. The demonstration of Sr{sup 2+} capture in carbonate mineral phases formed during bacterial HFO reduction and urea hydrolysis suggests that microbial carbonate mineral formation could contribute to Sr{sup 2+} retardation in groundwater environments. ...
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Strategic Design and Optimization of Inorganic Sorbents for Cesium, Strontium and Actinides

Strategic Design and Optimization of Inorganic Sorbents for Cesium, Strontium and Actinides

Date: October 6, 2004
Creator: Clearfield, Abraham; Tripathi, Akhilesh; Medvedev, Dmitri; Delgado, Jose & Kerlegon, Steve
Description: The basic science goal in this project identifies structure/affinity relationships for selected radionuclides and existing sorbents. The task will apply this knowledge to the design and synthesis of new sorbents that will exhibit increased cesium, strontium and actinide removal. The target problem focuses on the treatment of high-level nuclear wastes. The general approach can likewise be applied to non-radioactive separations.
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MANAGING TIGHT BINDING RECEPTORS FOR NEW SPEARATIONS TECHNOLOGIES

MANAGING TIGHT BINDING RECEPTORS FOR NEW SPEARATIONS TECHNOLOGIES

Date: December 10, 2004
Creator: GIVENS, DARYLE H BUSCH RICHARD S
Description: Much of the earth's pollution involves compounds of the metallic elements, including actinides, strontium, cesium, technetium, and RCRA metals. Metal ions bind to molecules called ligands, which are the molecular tools that can manipulate the metal ions under most conditions. This DOE-EMSP sponsored program strives (1) to provide the foundations for using the most powerful ligands in transformational separations technologies and (2) to produce seminal examples of their applications to separations appropriate to the DOE EM mission. These ultra tight-binding ligands can capture metal ions in the most competitive of circumstances (from mineralized sites, lesser ligands, and even extremely dilute solutions), but they react so slowly that they are useless in traditional separations methodologies. Two attacks on this problem are underway. The first accommodates to the challenging molecular lethargy by developing a seminal slow separations methodology termed the soil poultice. The second designs ligands that are only tight-binding while wrapped around the targeted metal ion, but can be put in place by switch-binding and removed by switch-release. We envision a kind of molecular switching process to accelerate the union between metal ion and tight-binding ligand. Molecular switching processes are suggested for overcoming the slow natural equilibration rate with which ultra ...
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Energetics of melts from thermal diffusion studies. FY 1993 progress report

Energetics of melts from thermal diffusion studies. FY 1993 progress report

Date: December 31, 1994
Creator: Lesher, C.E.
Description: This research program characterizes diffusional mass transport in geological fluids in response to thermal, solubility and chemical gradients using tools of experimental petrology. Quantitative information is obtained on the thermodynamic and kinetic properties of multicomponent systems that are the basis for predictive models of chemical diffusion, mineral dissolution, and complexing in synthetic and natural silicate systems. Among the technical accomplishments related to establishing the UCD experimental petrology laboratory in the last year has been the design and construction of two compact piston-cylinder devices capable of achieving 40 kb using 1/2-in. pressure vessels (also capable of accommodating 3/4-in. vessels). These machines are now on-line and performing thermal diffusion experiments. In addition to establishing the new laboratory at UCD, the PI began studies of molecular diffusion in the absence of a thermal gradient with results published on the chemical and self diffusion of Sr and Nd in naturally-occurring silicate liquids, and self diffusivities of Si and O in basaltic liquid.
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Spatial modulation of low-frequency spin fluctuations in hole-doped La{sub 2}CuO{sub 4}

Spatial modulation of low-frequency spin fluctuations in hole-doped La{sub 2}CuO{sub 4}

Date: December 1, 1996
Creator: Yamada, K.; Lee, C.H.; Wada, J.; Kurahashi, K.; Kimura, H.; Endoh, Y. et al.
Description: Systematic neutron scattering measurements have been performed on the Sr-doped La(2-x)Sr(x) CuO4 to study the doping dependence of spatially modulated dynamical spin correlations or so-called incommensurate spin fluctuations. The modulated spin correlations appears beyond x approx. 0.05 which is close to the lower boundary of the superconducting phase. First evidence was observed for the linear relation between the degree of spatial modulation or the incommensurability delta(x) and the maximum Tc at x. We present a universal curve for delta(x) by adding data from other La2CuO4 systems such as oxygen-doped superconductors, oxygen-reduced or Zn-substituted non-superconductors and La(1.6-x)Nd(0.4)Sr(x)CuO4.
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Cesium and Strontium Specific Exchangers for Nuclear Waste Effluent Remediation

Cesium and Strontium Specific Exchangers for Nuclear Waste Effluent Remediation

Date: September 1, 2000
Creator: Clearfield, A.; Bortun, A. I.; Bortun, L. A.; Bhlume, E. A.; Sylvester, P. & Graziano, G. M.
Description: During the past 50 years, nuclear defense activities have produced large quantities of nuclear waste that now require safe and permanent disposal. The general procedure to be implemented involves the removal of cesium and strontium from the waste solutions for disposal in permanently vitrified media. This requires highly selective sorbents or ion exchangers. Further, at the high radiation doses present in the solution, organic exchangers or sequestrants are likely to decompose over time. Inorganic ion exchangers are resistant to radiation damage and can exhibit remarkably high selectivities. We have synthesized three families of tunnel-type ion exchangers. The crystal structures of these compounds as well as their protonated phases, coupled with ion exchange titrations, were determined and this information was used to develop an understanding of their ion exchange behavior. The ion exchange selectivities of these phases could be regulated by isomorphous replacement of the framework metals by larger or smaller radius metals. In the realm of layered compounds, we prepared alumina, silica, and zirconia pillared clays and sodium micas. The pillared clays yielded very high Kd values for Cs+ and were very effective in removing Cs+ from groundwaters. The sodium micas also had a high affinity for Cs+ but an ...
Contributing Partner: UNT Libraries Government Documents Department
Treatment of oxide spent fuel using the lithium reduction process

Treatment of oxide spent fuel using the lithium reduction process

Date: May 1, 1996
Creator: Karell, E.J.; Pierce, R.D. & Mulcahey, T.P.
Description: The wide variety in the composition of DOE spent nuclear fuel complicates its long-term disposition because of the potential requirement to individually qualify each type of fuel for repository disposal. Argonne National Laboratory (ANL) has developed the electrometallurgical treatment technique to convert all of these spent fuel types into a single set of disposal forms, simplifying the qualification process. While metallic fuels can be directly processed using the electrometallurgical treatment technique, oxide fuels must first be reduced to the metallic form. The lithium reduction process accomplishes this pretreatment. In the lithium process the oxide components of the fuel are reduced using lithium at 650 C in the presence of molten LiCl, yielding the corresponding metals and Li{sub 2}O. The reduced metal components are then separated from the LiCl salt phase and become the feed material for electrometallurgical treatment. A demonstration test of the lithium reduction process was successfully conducted using a 10-kg batch of simulated oxide spent fuel and engineering-scale equipment specifically constructed for that purpose. This paper describes the lithium process, the equipment used in the demonstration test, and the results of the demonstration test.
Contributing Partner: UNT Libraries Government Documents Department
Combined Extraction of Cesium, Strontium, and Actinides from Alkaline Media: An Extension of the Caustic-Side Solvent Extraction (CSSX) Process Technology

Combined Extraction of Cesium, Strontium, and Actinides from Alkaline Media: An Extension of the Caustic-Side Solvent Extraction (CSSX) Process Technology

Date: November 3, 2004
Creator: Raymond, Kenneth
Description: The wastes present at DOE long-term storage sites are usually highly alkaline, and because of this, much of the actinides in these wastes are in the sludge phase. Enough actinide materials still remain in the supernatant liquid that they require separation followed by long-term storage in a geological repository. The removal of these metals from the liquid waste stream would permit their disposal as low-level waste and dramatically reduce the volume of high-level wastes.
Contributing Partner: UNT Libraries Government Documents Department
A combined cesium-strontium extraction/recovery process

A combined cesium-strontium extraction/recovery process

Date: March 1, 1996
Creator: Horwitz, E.P.; Dietz, M.L. & Jensen, M.P.
Description: A new solvent extraction process for the simultaneous extraction of cesium and strontium from acidic nitrate media is described. This process uses a solvent formulation comprised of 0.05 M di-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 0.1 M Crown 100{prime} (a proprietary, cesium-selective derivative of dibenzo-18-crown-6), 1.2 M tributyl phosphate (TBP), and 5% (v/v) lauryl nitrile in an isoparaffinic hydrocarbon diluent. Distribution ratios for cesium and strontium from 4 M nitric acid are 4.13 and 3.46, respectively. A benchtop batch countercurrent extraction experiment indicates that >98% of the cesium and strontium initially present in the feed solution can be removed in only four extraction stages. Through proper choice of extraction and strip conditions, extracted cesium and strontium can be recovered either together or individually.
Contributing Partner: UNT Libraries Government Documents Department
Separation of strontium from fecal matter

Separation of strontium from fecal matter

Date: December 31, 1994
Creator: Kester, D.K.
Description: The present invention relates to a method of separating strontium, and, more particularly, to a method of separating strontium from a sample of biomass potentially contaminated with various radionuclides. Radioactive strontium is a radionuclide which represents a hazard to man because of its long half-life and, if ingested, its tendency to be retained in the human body. In the event that radionuclides such as strontium or various actinides are ingested, it is desirable to monitor the discharge or release of these radionuclides from the human body through analysis of fecal matter. In laboratories and other facilities where potential for radionuclide contamination exists, fecal analysis for strontium is routinely conducted for individuals who are terminating from their position or are suspected of having been contaminated with radionuclides. Methods for separating and analyzing radioactive actinides from a biomass sample are well known and have been extensively developed for the US Department of Energy. These methods, described in the Department`s internal procedure, USDOE, RESL/ID, A-16, 1981, as well as in US Patent 5,190,881, involve the use of an iron phosphate precipitation step to separate actinides from a solution, or supernate. However, there are no established procedures for the separation of strontium from a ...
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Selective methane oxidation over promoted oxide catalysts. Quarterly report, March--May 1995

Selective methane oxidation over promoted oxide catalysts. Quarterly report, March--May 1995

Date: August 1, 1995
Creator: Klier, K.; Herman, R.G.; Wang, Chaun-Bao; Shi, Chunlei & Sun, Qun
Description: The objective of this research is the selective oxidative coupling of methane to C{sub 2}H{sub 4} hydrocarbons and oxygenates, in particular formaldehyde and methanol. Air, oxygen or carbon dioxide, rather than nitrous oxide will be utilized as the oxidizing gas at high gas hourly space velocity, but mild reaction conditions (500-700 {degrees}C, 1 atm total pressure). All the investigated processes are catalytic, aiming at minimizing gas phase reactions that are difficult to control. The research is divided into the following three tasks: (1) maximizing selective methane oxidation to C{sub 2}H{sub 4} products over promoted Sr/La{sub 2}O{sub 3}; (2) selective methane oxidation to oxygenates; and (3) catalyst characterization and optimization. Task 1 dealt with the preparation, testing, and optimization of acidic promoted lanthana-based catalysts for the synthesis of C{sub 2}H{sub 4} hydrocarbons and is essentially completed. Task 2 aims at the formation and optimization of promoted catalysts for the synthesis of oxygenates, in particular formaldehyde and methanol. Task 3 involves characterization of the most promising catalysts so that optimization can be achieved under Task 2. Accomplishments for this period are presented.
Contributing Partner: UNT Libraries Government Documents Department
Selective methane oxidation over promoted oxide catalysts. Quarterly report, September--November, 1994

Selective methane oxidation over promoted oxide catalysts. Quarterly report, September--November, 1994

Date: December 1, 1994
Creator: Klier, K.; Herman, R.G.; Shi, C.; Wang, C.B. & Sun, Q.
Description: Experimental research in the direct conversion of methane to methanol using a double bed reactor and with gaseous steam as cofeed with the CH{sub 4}/air reactant mixture continued during this quarter in order to improve the methanol space time yield. Work was carried out along several pathways that included a stability test of the second bed catalyst 1%V{sub 2}O{sub 5}/SiO{sub 2} that yielded up to 100 g methanol/kg cat/hr and investigation of the effect of pressure on methanol yields. Redox dopants were put onto several metal oxide supports in an attempt to find better second bed catalysts. A catalyst that was reasonably selective towards oxygenates was obtained when SiO{sub 2} was used as the support and low quantities of Fe or Cu were utilized. Attempts were also made to incorporate alkali ions into the catalysts to improve the surface hydrolyzability. Experiments were carried out to examine the effect of pressure and temperature on the oxygenate productivity over a double-layered catalyst bed of 0.1 g 1 wt% SO{sub 4}{sup 2{minus}}/Sr/La{sub 2}O{sub 3} as the first bed and 0.1 g 1 wt% V{sub 2}O{sub 5}/SiO{sub 2} as the second bed without H{sub 2}O cofeed in a glass-lined tubular down-flow reactor at pressures ...
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Identification and validation of heavy metal and radionuclide accumulating terrestrial plant species. Quarterly technical progress report, June 21, 1995--September 20, 1995

Identification and validation of heavy metal and radionuclide accumulating terrestrial plant species. Quarterly technical progress report, June 21, 1995--September 20, 1995

Date: December 31, 1995
Creator: Kochian, L.
Description: This quarterly report describes experiments on uptake of a variety of heavy metals by plants. Titles of report sections are (1) Alleviation of heavy-metal induced micronutrient deficiency through foliar fertilization, (2) Second screen for Zn, Cu, and Cd accumulation, (3) Characterization of the root Zn hyperaccumulation by Thlaspi caerulescens, (4) Comparison of commercial Brassica accessions obtained from the Iowa seed bank, (5) Second screening experiment for the accumulation of Cs and Sr by plants, (6) Effect of Ca on Cs and Sr accumulation by selected dicot species, and (7) Preliminary investigations into the forms of uranium taken up by plants.
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Identification and validation of heavy metal and radionuclide hyperaccumulating terrestrial plant species. Quarterly technical progress report, March 20, 1995--June 20, 1995

Identification and validation of heavy metal and radionuclide hyperaccumulating terrestrial plant species. Quarterly technical progress report, March 20, 1995--June 20, 1995

Date: December 1, 1995
Creator: Kochian, L.
Description: The biological accumulation of heavy metals and cesium, strontium, and uranium in plants is discussed. The role of nutrient deficiencies and foliar treatments of manganese and iron compounds is described.
Contributing Partner: UNT Libraries Government Documents Department
Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors

Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors

Date: December 16, 2004
Creator: Linak, William
Description: Sorption of cesium and strontium on kaolinite powders was investigated as a means to minimize the emissions of these metals during certain high temperature processes currently being developed to isolate and dispose of radiological and mixed wastes. In this work, non-radioactive aqueous cesium acetate or strontium acetate was atomized down the center of a natural gas flame supported on a variable-swirl burner in a refractory-lined laboratory-scale combustion facility. Kaolinite powder was injected at a post-flame location in the combustor. Cesium readily vaporizes in the high temperature regions of the combustor, but was reactively scavenged onto dispersed kaolinite. Global sorption mechanisms of cesium vapor on kaolinite were quantified, and are related to those available in the literature for sodium and lead. Both metal adsorption and substrate deactivation steps are important, and so there is an optimum temperature, between 1400 and 1500 K, at which maximum sorption occurs. The presence of chlorine inhibits cesium sorption. In contrast to cesium, and in the absence of chlorine, strontium was only partially vaporized and was, therefore, only partially scavengeable. The strontium data did not allow quantification of global kinetic mechanisms of interaction, although equilibrium arguments provided insight into the effects of chlorine on strontium sorption. ...
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NNWSI waste form test method for unsaturated disposal conditions

NNWSI waste form test method for unsaturated disposal conditions

Date: March 1, 1985
Creator: Bates, J.K. & Gerding, T.J.
Description: A test method has been developed to measure the release of radionuclides from the waste package under simulated NNWSI repository conditions, and to provide information concerning materials interactions that may occur in the repository. Data are presented from Unsaturated testing of simulated Savannah River Laboratory 165 glass completed through 26 weeks. The relationship between these results and those from parametric and analog testing are described. The data indicate that the waste form test is capable of producing consistent, reproducible results that will be useful in evaluating the role of the waste package in the long-term performance of the repository. 6 refs., 7 figs., 5 tabs.
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Aqueous complexes in f-element separation science

Aqueous complexes in f-element separation science

Date: November 1, 1997
Creator: Nash, K.L.
Description: Powerful and/or selective extractant molecules/sorbents are a necessary component of an efficient ion exchange or solvent extraction separation process. However, selectivity in extraction and efficiency in process design often rely on reactions occurring in or moderated by the aqueous medium. The focus of this report in on the role of the aqueous phase and reaction that occur in aquo in defining separation efficiency and metal ion selectivity. As the programmatic emphasis is on actinide solution chemistry, the separations chemistry of the f-elements will be used to illustrate the principal role of aqueous chemistry in separation science. Most of the arguments developed apply to metal ion separations chemistry and processes in general. The discussion will consider the application of aqueous complexants, incorporation of aqueous complexants into the extracted complex, and the effect of properties of the aqueous medium on separation efficiency and selectivity. Several historically important separations processes will be considered along with recent efforts in these laboratories to design and characterize new water soluble complexants for improved f-element separations.
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