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Application of ideal reactors to studies in atmospheric chemistry

Description: Mass-transfer effects and surface reactions may severely obscure the observation of homogeneous chemical reaction rates from experimental reactor data. Such problems are particularly pertinent to studies in the atmospheric sciences, owing to the tendency for increased surface-reaction interference at the low concentrations usually of interest. Criteria are presented for ideal behavior in three basic types of experimental reactors. Under conditions satisfying these criteria the effects of competing surface reactions can be accounted for quantitatively, allowing the true homogeneous effect to be observed. Data from tubular reactors can be analyzed accurately even under some nonideal conditions. The available solutions to tubular reactor models useful for this purpose were compiled and tabulated. (auth)
Date: August 1, 1973
Creator: Hales, J.M.; Wilkes, J.O. & York, J.L.
Partner: UNT Libraries Government Documents Department
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Aqueous electrochemical mechanisms in actinide residue processing. 1998 annual progress report

Description: 'New and/or improved solutions to the stabilization and volume reduction of nuclear materials processing residues are urgently needed. Mediated electrochemical oxidation/reduction (MEO/R) processes are one such approach for incinerator ash, combustibles, and other solid residues. However, questions remain concerning the mechanisms of these processes, and how they might be optimized. In addition, further research is merited to extend their range of applicability. Recent advances in the study of heterogeneous electron transfer in solid substrates have opened the door for the re-examination of electron transfer processes associated with redox mediated actinide dissolution. The authors develop a deeper understanding of the thermodynamic and mechanistic aspects of heterogeneous electron transfer that lie at the heart of these MEO/R processes. They will also develop and test new approaches based on the results of these fundamental studies using actual residue materials. Key aspects of this proposal include: (1) determination of the potential windows for oxidation/reduction of colloidal actinide oxides and actinide-bearing oxide and organic substrates and the e transfer kinetic parameters that govern the current--overpotential characteristics; (2) development of adaptations of mediation schemes and application of co-mediation reagents for oxidative and reductive dissolution based on complexation of the surface-bound or solid-phase actinides and/or the dissolved redox mediator;and (3) execution of bench-scale tests of new MEO/R schemes on actual residue materials.'
Date: June 1, 1998
Creator: Morris, D.E.; Burns, C.J.; Smith, W.H. & Blanchard, D.L. Jr.
Partner: UNT Libraries Government Documents Department
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Chemical speciation of strontium, americium, and curium in high level waste: Predictive modeling of phase partitioning during tank processing. Annual progress report, October 1996--September 1997

Description: 'The program at Florida State University was funded to collaborate with Dr. A. Felmy (PNNL) on speciation in high level wastes and with Dr. D. Rai (PNNL) on redox of Pu under high level waste conditions. The funding provided support for 3 research associates (postdoctoral researchers) under Professor G. R. Choppin as P.I. Dr. Kath Morris from U. Manchester (Great Britain), Dr. Dean Peterman and Dr. Amy Irwin (both from U. Cincinnati) joined the laboratory in the latter part of 1996. After an initial training period to become familiar with basic actinide chemistry and radiochemical techniques, they began their research. Dr. Peterman was assigned the task of measuring Th-EDTA complexation prior to measuring Pu(IV)-EDTA complexation. These studies are associated with the speciation program with Dr. Felmy. Drs. Morris and Irwin initiated research on redox of plutonium with agents present in the Hanford Tanks as a result of radiolysis or from use in separations. The preliminary results obtained thus far are described in this report. It is expected that the rate of progress will continue to increase significantly as the researchers gain more experience with plutonium chemistry.'
Date: December 31, 1997
Creator: Felmy, A.R. & Choppin, G.
Partner: UNT Libraries Government Documents Department
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F-Element ion chelation in highly basic media. Annual progress report, October 1, 1996--July 1, 1997

Description: 'The specific fundamental chemical objectives of this project are to: (1) study the chemical speciation of Sr and Ln ions in basic media formed in aqueous solutions with and without classical chelation agents (e.g., EDTA, polyphosphates, and organic carboxylates); (2) prepare pyridine N-oxide phosphonate and phosphonoacetate chelators of the types 1--3 and characterize their ionization properties by titrimetric techniques; (3) study the interactions of 5--7 with soluble oxide-hydroxide metallate species and higher molecular weight sols, gels and precipitates containing Sr and Ln ions, as time permits, interactions with oxide-hydroxide metallates of U, Th, Ba, Al and Fe will also be studied; (4) study the interactions of newly designed phosphonate ligands with oxide-hydroxide metallate species; (5) transfer the fundamental coordination chemistry revealed here to research groups at LANL and PNNL that will utilize the results to improve tank waste treatment protocols.'
Date: December 31, 1997
Creator: Paine, R. T.
Partner: UNT Libraries Government Documents Department
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F-Element ion chelation in highly basic media. 1998 annual progress report

Description: 'A large percentage of high-level radioactive waste (HLW) produced in the DOE complex over the last thirty years temporarily resides in storage tanks maintained at highly basic pH. The final permanent waste remediation plan will probably require that liquid and solid fractions be chemically treated in order to partition and concentrate the dominate hazardous emitters from the bulk of the waste. This is no small task. Indeed, there does not exist a well developed molecular chemistry knowledge base to guide the development of suitable separations for actinide and fission products present in the strongly basic media. The goal of this project is to undertake fundamental studies of the coordination chemistry of f-element ions and their species formed in basic aqueous solutions containing common waste treatment ions (e.g., NO{sub 3}{sup -}, CO{sub 3}{sup 2-}, organic carboxylates, and EDTA), as well as new waste scrubbing chelators produced in this study.'
Date: June 1, 1998
Creator: Paine, R.T.
Partner: UNT Libraries Government Documents Department
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General method for computation of equilibrium composition and temperature of chemical reactions

Description: Report presenting an approximation process that can be used to determine both composition and temperature resulting from a chemical reaction. It is suitable for use with any set of reactants over the complete range of mixture ratios as long as the products of reaction are ideal gases.
Date: June 1950
Creator: Huff, Vearl N. & Morrell, Virginia E.
Partner: UNT Libraries Government Documents Department
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