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A study of competitive adsorption of organic molecules onto mineral oxides using DRIFTS

Description: Analysis of DRIFTS spectra was used for a quantitative study of competitive adsorption of myristic and salicylic acids onto kaolinite or {gamma}-alumina. Peaks unique to the ring or the chain were selected and single molecule studies used as calibration. Samples were exposed to hexane solution containing equal molecular quantities of each acid. The surface loading of salicylic acid was not influenced by the presence of myristic acid on either mineral but the maximum loading of myristic acid was decreased (46-50%) by salicylic acid. Displacement of myristic acid from {gamma}-alumina, but not kaolinite, was observed when excess salicylic acid remained in solution. A 25% increase in the maximum loading was observed for kaolinite, but not for{gamma}-alumina. On {gamma}-alumina, after a loading of 1 molecule per nm{sup 2}, increased exposure resulted in salicylic acid adsorption only, this value is approximately the same for salicylic acid adsorption from aqueous solution or for water washed hexane treated samples. Thus a set of sites for adsorption of either acid is indicated together with other energetically less favorable sites, which can be occupied by salicylic, but not by myristic, acid.
Date: February 1, 2010
Creator: Joan E. Thomas, Michael J. Kelley
Partner: UNT Libraries Government Documents Department

Final Technical Report: Effects of Impurities on Fuel Cell Performance and Durability

Description: The main objectives of this project were to investigate the effect of a series of potential impurities on fuel cell operation and on the particular components of the fuel cell MEA, to propose (where possible) mechanism(s) by which these impurities affected fuel cell performance, and to suggest strategies for minimizing these impurity effects. The negative effect on Pt/C was to decrease hydrogen surface coverage and hydrogen activation at fuel cell conditions. The negative effect on Nafion components was to decrease proton conductivity, primarily by replacing/reacting with the protons on the Bronsted acid sites of the Nafion. Even though already well known as fuel cell poisons, the effects of CO and NH3 were studied in great detail early on in the project in order to develop methodology for evaluating poisoning effects in general, to help establish reproducibility of results among a number of laboratories in the U.S. investigating impurity effects, and to help establish lower limit standards for impurities during hydrogen production for fuel cell utilization. New methodologies developed included (1) a means to measure hydrogen surface concentration on the Pt catalyst (HDSAP) before and after exposure to impurities, (2) a way to predict conductivity of a Nafion membranes exposed to impurities using a characteristic acid catalyzed reaction (methanol esterification of acetic acid), and, more importantly, (3) application of the latter technique to predict conductivity on Nafion in the catalyst layer of the MEA. H2-D2 exchange was found to be suitable for predicting hydrogen activation of Pt catalysts. The Nafion (ca. 30 wt%) on the Pt/C catalyst resides primarily on the external surface of the C support where it blocks significant numbers of micropores, but only partially blocks the pore openings of the meso- and macro-pores wherein lie the small Pt particles (crystallites). For this reason, even with 30 wt% Nafion ...
Date: November 11, 2011
Creator: Goodwin, James G., Jr.; Colon-Mercado, Hector; Hongsirikarn, Kitiya & Zhang, Jack Z.
Partner: UNT Libraries Government Documents Department

A GELATIN-FILTRATION HEADEND FOR FUEL REPROCESSING SOLUTIONS FROM SILICON- CONTAINING ALUMINUM ALLOYS

Description: A laboratory study of a gelatin headend process for feed from silicon- containing aluminum fuels and plant salvage solutions is described. The optimum conditions for the gelatin treatment of fuel solutions were to boil a 0.1 to 0.5N nitric acid solution with 100 milligrams of gelatin per liter for 30 minutes. This treatment improved filtration rates and decreased the surface activity of the filtrate for TBP extraction. A number of possible flowsheets for fuel solutions are presented using gelatin treatment and filtration. An adequate treatment was not found for salvage solutions of unknown composition because a gelatin dosage which was satisfactory for all solutions could not be selected. The optimum treatment for a salvage solution which was grossly contaminated with zirconium, soluble and colloidal silica, and dibutyl phosphate was to boil a 1N acid deficient solution with 600 milligrams of gelatin per liter, filter, and use a Hexone extraction system. A silicic colloid in fuel processing solutions was characterized as a surface active material by this study. (auth)
Date: February 1, 1959
Creator: Newby, B.J. & Paige, B.E.
Partner: UNT Libraries Government Documents Department

IDAHO CHEMICAL PROCESSING PLANT TECHNICAL PROGRESS REPORT FOR JANUARY- MARCH 1960

Description: 9 > ? ( ing schedule included MTR, ETR, and other aluminum-type fuels that were processed through the TBP headend at 75 to 100% of flowsheet rates and through the Hexone second and third cycle extraction system at up to l5O% of flowsheet values, achieving an over-all recovery of 99.60%. In carrying out basic studies on aqueous zirconium processing, results obtained during the potentiometric titration of zirconium-fluoride-nitric acid solutions with sodium hydroxide were explained by a mechanism in which the untitrated zirconium fluoride species is converted to a fluozirconate and further hydrolysis proceeds via a fluozirconate route. A modified Zirflex flowsheet for processing 2.5% U-Zr alloy fuels is proposed as a result of bench scale dissolution studies on unirradiated PWR plates that showed that dissolver solutions could be stabilized by adding aluminum nitrate and nitric acid. that higher ammonium fluoride concentrations increased the dissolution rate, that higher hydrogen peroxide concentrations lowered the dissolution rate and decreased solution stability, and that ammonia removal by boiling with or without air sparging had little effect on the reaction. Density curves for Zirflex solutions are reported. First tests of the pilot plant for continuous dissolution of zirconium-type elements have indicated that the dissolution rate is approximately four times as great as predicted on the basis of batch dissolution rates and comparison with the rate ratio for batch vs. continuous dissolution of aluminum, which was used to establish the dissolver size. The continuous dissolution rate for a 2% zirconium- 98% uranium element was approximately proportional to the acid feed rate and reached l9O kg/day at an acid feed rate of 36 l/hr (11M nitric acid, 0.30M hydrofluoric acid, and 0.35M aluminum nitrate). Development of new waste treatment methods is influenced by waste volumes and the associated storage costs involved. A survey of current and proposed ...
Date: July 13, 1960
Creator: Slansky, C.M.; Warzel, F.M. & Bower, J.R. Jr. ed.
Partner: UNT Libraries Government Documents Department

IMPROVED ANTIFOAM AGENT STUDY END OF YEAR REPORT, EM PROJECT 3.2.3

Description: Antifoam 747 is added to minimize foam produced by process gases and water vapor during chemical processing of sludge in the Defense Waste Processing Facility (DWPF). This allows DWPF to maximize acid addition and evaporation rates to minimize the cycle time in the Chemical Processing Cell (CPC). Improvements in DWPF melt rate due to the addition of bubblers in the melter have resulted in the need for further reductions in cycle time in the CPC. This can only be accomplished with an effective antifoam agent. DWPF production was suspended on March 22, 2011 as the result of a Flammable Gas New Information/(NI) Potential Inadequacy in the Safety Analysis (PISA). The issue was that the DWPF melter offgas flammability strategy did not take into account the H and C in the antifoam, potentially flammable components, in the melter feed. It was also determined the DWPF was using much more antifoam than anticipated due to a combination of longer processing in the CPC due to high Hg, longer processing due to Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) additions, and adding more antifoam than recommended. The resolution to the PISA involved and assessment of the impact of the antifoam on melter flammability and the implementation of a strategy to control additions within acceptable levels. This led to the need to minimize the use of Antifoam 747 in processing beginning in May 2011. DWPF has had limited success in using Antifoam 747 in caustic processing. Since starting up the ARP facility, the ARP product (similar chemically to caustic sludge) is added to the Sludge Receipt and Adjustment Tank (SRAT) at boiling and evaporated to maintain a constant SRAT volume. Although there is very little offgas generated during caustic boiling, there is a large volume of water vapor produced which can ...
Date: September 30, 2011
Creator: Lambert, D.; Koopman, D. & Newell, J.
Partner: UNT Libraries Government Documents Department

SYNTHESIS OF METAL HYDRIDES BY MECHANICAL ALLOYING IN AN ATTRITOR MILL: FY07 STATUS REPORT

Description: The objective of this task was to demonstrate that metal hydrides could be produced by mechanical alloying in the quantities needed to support the tritium production facilities at the Savannah River Site. The objective for the FY07 portion of this task was to demonstrate the production of Zr-Fe getter materials by mechanical alloying and begin to optimize the milling parameters. Three starting compositions (ratios of elemental Zr and Fe powders) were selected and attritor milled under argon for times of 8 to 60 hours. Hexane and liquid nitrogen were used as process control agents. In general, milling times of at least 24 hours were required to form the desired Zr{sub 2}Fe and Zr{sub 3}Fe phases, although a considerable amount of unalloyed Zr and Fe remained. Milling in liquid nitrogen does not appear to provide any advantages over milling in hexane, particularly due to the formation of ZrN after longer milling times. Carbides of Zr formed during some of the milling experiments in hexane. Formation of carbides during milling appears to be much less of an issue than formation of nitrides, although some of the phases that were not able to be identified in the XRD results may also be carbides. Additional XRD experiments should be designed to improve signal to noise ratio (i.e., longer count times) and use a wider scan range to better identify phases that were not clear in the original data. Elemental Zr was present in the as-milled material but not detected after annealing for milling times of 48 and 60 hours. It may be that after intimate mixing of the powders in the attritor mill the annealing temperature was sufficient to allow for the formation of a Zr-Fe alloy. The phase diagram for the binary Zr-Fe system agrees with this proposition. If this is the case, ...
Date: November 8, 2007
Creator: Fox, K
Partner: UNT Libraries Government Documents Department

MECHANICAL ALLOYING AND THERMAL TREATMENT FOR PRODUCTION OF ZIRCONIUM IRON HYDROGEN ISOTOPE GETTERS

Description: The objective of this task was to demonstrate that metal hydrides could be produced by mechanical alloying in the quantities needed to support production-scale hydrogen isotope separations. Three starting compositions (ratios of elemental Zr and Fe powders) were selected and attritor milled under argon for times of 8 to 60 hours. In general, milling times of at least 24 hours were required to form the desired Zr{sub 2}Fe and Zr{sub 3}Fe phases, although a considerable amount of unalloyed Zr and Fe remained. Milling in liquid nitrogen does not appear to provide any advantages over milling in hexane, particularly due to the formation of ZrN after longer milling times. Carbides of Zr formed during some of the milling experiments in hexane. Elemental Zr was present in the as-milled material but not detected after annealing for milling times of 48 and 60 hours. It may be that after intimate mixing of the powders in the attritor mill the annealing temperature was sufficient to allow for the formation of a Zr-Fe alloy. Further investigation of this conversion is necessary, and could provide an opportunity for reducing the amount of unreacted metal powder after milling.
Date: February 20, 2008
Creator: Fox, K.
Partner: UNT Libraries Government Documents Department

EUROCHEMIC ASSISTANCE: CHEMICAL TECHNOLOGY DIVISION UNIT OPERATIONS SECTION MONTHLY PROGRESS REPORT, DECEMBER 1958. (SECTIONS 5.0, 6.0, 8.0)

Description: A study of the equiibrium sorption isotherms and rates of U sorption on Dowex 21K is in progress. Data which show the effects of uranium concentration in solution on resin loading are presented Fuel reprocessing experiments are reported in which efforts were made to reduce Cl- in Darex dissolver solution to < 350 ppm for the extraction phase. The best method of Cl/sup -/ reduction appears to be operation with a down draft condenser and an air sparge. A check- out dissolution min in the 6 in. glass dissolver with a prototype APPR fuel element is reported, and data on dissolution time and composition of reacted products are given. Data on filtration rates for Darex solutions expected in large-scale operations are tabulated, and graphs illustrating the effects of pressure drop and filter aids on filtering rates are presented. Tests on washing U from filter cakes indicate that U can be removed to any desired level. Viscosity, density. and boiling points as a function of temperature or pressure were determined for two Darex solvent extraction feed solutions; data are presented grahically, and results of chemical analyses are tabuated. Demonstation runs for Sulfex and Zirflex dejacketing flowsheets were made. Results indicate that parts of the Sulfex flowsheet map have to be changed to prevent core losses from fluoride contamination. Results from the Zirflex demonstration are being compiled. Design of the SRE decanning device was completed and sub mitted to vendors for bids; also the design of a prototype fuel bundle to serve as an inexpensive substitute in chopping and leaching studies is reported. Preliminary shearing studies with the 120 ton hydraulic Manco shear indicate that its usefulness is limited, and criteria for a large shear for spent fuel bundles are being written. Darex-type solvent extraction studies using hexane are reported, and U ...
Date: May 1, 1959
Creator: Shank, E M
Partner: UNT Libraries Government Documents Department

THE USE OF TRI-n-OCTYLPHOSPHINE OXIDE IN THE SOLVENT EXTRACTION OF THORIUM FROM ACIDIC SOLUTIONS

Description: Thorium is readily extracted by a solution of tri-noctylphosphine oxide in cyclohexane from either acidic nitrate or chloride solutions. The maximum extraction coefficient in a nitrate medium is 380 as compared to 1300 for a chloride solution. In nitrate media the extraction coefficient is relativelv unaffected by changes in the anion concentration. In chloride media the coefficient varies directly with increasing chloride concentration, i.e., from about 0.4 in one molar chloride to the maximum in 7 to 10 molar. The acid concentration should be at least one molar. Thorium is not appreciably extracted from sulfate solutions. The extraction coefficient is of the order of 0.3. The addition of nitrate or chloride increases the coefficient sufficiently so that essentially 99% of the thorium can be extracted in a single equilibration. In perchlolate systems the extractlon is most efficient in one molar acid. The maximum (The above was unscabble material)
Date: November 20, 1958
Creator: Ross, W.J. & White, J.C.
Partner: UNT Libraries Government Documents Department

Mound Laboratory Progress Report for September 1963

Description: Three silicone-based conductive adhesives were formulated and evaluated. One of the formulations had a resistivity of 0.089 ohm-centimeter after aging one week. After the same period the other two formulations had resistivities of 0.871 and 38.0 ohm-centimeters, Erratic adsorptive behavior of / sup 140/Ba was traced to in impurity in the Ba--/sup 140/La stock solution. Repurification by cation exchange did not improve the reproducibility of the separations, possibly because impurities are reintroduced by the distilled water. Definite improvement was noted when the /sup 140/Ba was separated from /sup 140/ La and other hydrolyzable materials by residue adsorption methods. A calorimetric measurement of a salt sample over a period of 148 days gave a tritium half life of 12.361 plus or minus 0.028 years. This value confirmed the earlier value of l2.355 plus or minus 0.028 years. The /sup 208/Po--/sup 209/Po mixture returned from Argonne National Laboratory is being processed further. Two batches of polonium-contaminated organic material were wet-ashed in nitric and perchloric acids. Further purification will be by techniques similar to those presently used for separating /sup 210/Po from bismuth. An unidentified gamma activity was found in the polonium that was recovered from pieces of Monel fluorination apparatus. The optimum conditions for decontamination of polonium process waste are being determined. Ferric sulfate was dissolved in the solution, and the pH was adjusted to a value between 7.0 and 12.0 to precipitate ferric hydroxide. However, the alpha and beta activity was not decreased sufficiertly to allow dumping of the wastes without further processing. A method of separating /sup 227/Ac from a mixture of its daughter products and /sup 226/Ra is being developed using ion exchange and solvent extraction techniques. Substituted elements are being used to evaluate the separation procedures prior to the separation of the radioactive isotopes. More than 99% of ...
Date: September 30, 1963
Creator: Eichelberger, J. F.; Grove, G. R. & Jones, L. V.
Partner: UNT Libraries Government Documents Department

AN ORIFICE PLATE PULSE COLUMN FOR LIQUID-LIQUID EXTRACTION (thesis)

Description: A study was made of the performance of an orifice plate pulse column which is essentially a spray column containing internal constrictions in the form of orifices. The chemical system studied was acetic acid-waterhexone, and the variables considered were pulse frequency, throughput, phase continuity, and direction of solute transfer. For comparison purposes, several runs were made with a conventional spray column. Curves are presented showing the effect of the column variables on the column efficiency (HTU). The trends observed are explained as being due principally to the competing effects of the area for mass transfer and back-mixing. Photographs of a typical column section show qualitatively the effect of the important column variables. (auth)
Date: August 23, 1954
Creator: O'Brien, D.C.
Partner: UNT Libraries Government Documents Department

A Low-Temperature Calorimetric Cryostat

Description: A low temperature adiabatic cryostat for determining precise calorimetric data has been described. The accuracy of the data produced by this apparatus has been established by measuring the thermal properties of n-hexane up to 300 deg K. These data agree with available precise data, in general, to within 0.2%. The precision of the heat capacity measurements is, for the most part, better than 0.1%. (auth)
Date: January 20, 1950
Creator: Oliver, G.D.; Grisard, J.W. & Anderson, V.E.
Partner: UNT Libraries Government Documents Department