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Reduction of sample volume and waste generation in acid/base titrations using microelectrodes

Description: The Analytical Development Section (ADS) has developed microelectrode methods for use with pH titrations and pH determinations. These microelectrode methods offer increased sensitivity and enable analyses to be done with smaller sample and buffer volumes than are used with standard size electrodes. This report establishes the technical validity of the methods and describes the application of these methods to decreased detection limits, decreased waste generation, and decreased radiation exposure.
Date: March 22, 1996
Creator: Ekechukwu, A.A.
Partner: UNT Libraries Government Documents Department

Transformation of Pb(II) from Cerrusite to Chloropyromorphite in the Presence of Hydroxyapatite under Varying Conditions of pH

Description: Cerrusite (PbC03) is soluble under acidic conditions and considered to be a highly bioavailable soil Pb species. In this study, synthetic cerrusite and hydroxyapatite [Ca5(P04)30H] were reacted under constant and dynamic pH conditions with various P/Pb molar ratios in an attempt to evaluate the effect of reaction kinetics on the formation of chloropyromorphite (Pb5(P04)3Cl) and solubilization of Pb. Under constant pH conditions, dissolution rates of both cerrusite and apatite were rapid when pH was low. Complete conversion of Pb from cerrusite to chloropyromorphite occurred within 60 tin at pH 4 and below when the amount of phosphate in the added apatite was stoichoimetrically equal to that needed to transform all added Pb into chloropyromorphite. The concentration of soluble Pb depended upon the volubility of chloropyromorphite. The dissolution rates of apatite and cerrusite decreased with increasing pH, and the transformation was incomplete at pH 5 and above in the 60 rnin reaction period. The soluble Pb level, therefore, was determined by the volubility of cerrusite. In the dynamic pH system which simulated the gastrointestinal tract (GI tract) system, a complete transformation of Pb from cerrusite to chloropyromorphite was achieved due to the complete dissolution of apatite and cerrusite at the initial low pHs. Chloropyromorphite was the exclusive reaction product in both constant and dynamic pH systems as indicated by XRD analysis. The differences in transformation rate and the control of Pb volubility between the reactions occurring in constant and dynamic pH systems indicate the significance of kinetics in controlling the bioavailability of Pb and the potential for the reaction to occur during ingestion.
Date: October 14, 1998
Creator: Ryan, J.A. & Zhang, P.
Partner: UNT Libraries Government Documents Department

Batch Microreactor Studies of Base Catalyzed Ligin Depolymerization in Alcohol Solvents

Description: The depolymerization of organosolv-derived lignins by bases in methanol or ethanol solvent was studied in rapidly heated batch microreactors. The conversion of lignin to ether solubles by KOH in methanol or ethanol was rapid at 290 "C, reaching the maximum value within 10-15 minutes. An excess of base relative to Lignin monomer units was required for maximum conversion. Strong bases (KOH, NaOH, CSOH) convert more of the lignin to ether soluble material than do weaker bases LiOH, Ca(OH)2, and NacCO2). Ethanol and methanol are converted to acetic and formic acid respectively under the reaction conditions with an activation energy of approximately 50 kcal/mol. This results in a loss of solvent, but more importantly neutralizes the base catalyst, halting forward progress of the reaction.
Date: February 3, 1999
Creator: Evans, L.; Littlewolf, A.; Lopez, M. & Miller, J.E.
Partner: UNT Libraries Government Documents Department

Structures and charging of alpha-alumina (0001)/water interfaces studies by sum-frequency vibrational spectroscopy

Description: Sum-frequency vibrational spectroscopy in the OH stretch region was employed to study structures of water/{alpha}-Al{sub 2}O{sub 3} (0001) interfaces at different pH values. Observed spectra indicate that protonation and deprotonation of the alumina surface dominate at low and high pH, respectively, with the interface positively and negatively charged accordingly. The point of zero charge (p.z.c.) appears at pH {approx}6.3, which is close to the values obtained from streaming potential and second harmonic generation studies. It is significantly lower than the p.z.c. of alumina powder. The result can be understood from the pK values of protonation and deprotonation at the water/{alpha}-Al{sub 2}O{sub 3} (0001) interface. The p.z.c. of amorphous alumina was found to be similar to that of powder alumina.
Date: November 10, 2008
Creator: Zhang, L.; Tian, C.; Waychunas, G.A. & Shen, Y.R.
Partner: UNT Libraries Government Documents Department

Anodonta imbecillis QA Test 1, Clinch River - Environmental Restoration Program (CR-ERP)

Description: Toxicity testing of split whole sediment samples using juvenile freshwater mussels (Anodonta imbecillis) was conducted by TVA and CR-ERP personnel as part of the CR-ERP biomonitoring study of Clinch River sediments to provide a quality assurance mechanism for test organism quality and overall performance of the test. In addition, testing included procedures comparing daily renewal versus non-renewal of test sediments. Testing of sediment samples collected July 15 from Poplar Creek Miles 6.0 and 5.1 was conducted from July 21-30, 1993. Results from this test showed no toxicity (survival effects) to fresh-water mussels during a 9-day exposure to the sediments. Side by side testing of sediments with daily sediment renewal and no sediment renewal showed no differences between methods. This may be due to the absence of toxicity in both samples and may not reflect true differences between the two methods for toxic sediment.
Date: June 1, 1997
Creator: Simbeck, D.J.
Partner: UNT Libraries Government Documents Department

Development of the indicator-photopolymer chemistries for multianalyte sensor arrays

Description: Remediation of ground and waste water facilities requires the analysis of the pollutants. Multianalyte fiber-optic chemical sensors based on indicators have been developed, with multiple indicators immobilized at the distal end of a single imaging fiber. By coupling the imaging fibers to a charge coupled device detector, one can spatially and spectrally discriminate the multiple sensing sites and hence monitor multiple analyte concentrations simultaneously. This report describes the development of the indicator chemistry and immobilization procedures developed for pH, Al{sup 3+}, and hydrocarbons. A polymer matrix is used to mass transfer the analyte to the indictor.
Date: January 1, 1995
Creator: Healey, B.G.; Chadha, S.; Walt, D.R.; Richards, J.B.; Brown, S.B. & Milanovich, F.P.
Partner: UNT Libraries Government Documents Department

Consequence analysis of a NaOH solution spray release during addition to waste tank. Revision 2

Description: Toxicological consequences are presented for three postulated accidents involving caustic soda (sodium hydroxide) addition to a waste tank to adjust the tank waste pH. These are spray from the skid mounted delivery system, spray from a cargo tank truck, and rupture of a cargo tank truck. Consequences for the onsite and offsite receptor are calculated.
Date: July 8, 1997
Creator: Van Vleet, R.J. & Lancing, L.C.
Partner: UNT Libraries Government Documents Department

Effect of pH on the growth of KDP

Description: The acidity of KDP salt solution is one of the important parameters. This parameter determines a lot of properties of solution, crystallization processes in solution, properties of grown crystals. An alteration of the KDP salt solution acidity changes it`s properties such as KDP salt volubility, stability of the KDP solution, solution density, solution viscosity, solution heat capacity, etc. It also changes state of impurities in the solution and characteristics of interaction between growing faces of the crystal and solution impurities. As a result kinetics of crystallization changes, habit and physical properties of the grown crystal change too. It should be mentioned that investigations in were done for low rate processes of crystal growth. Here we report the results of our investigations which have been done for high rate crystal growth processes (R{sub Z} {approx} 20 mm/day).
Date: March 20, 1998
Creator: Rashkovich, L. N.
Partner: UNT Libraries Government Documents Department

Production and preliminary testing of multianalyte imaging sensor arrays

Description: This report covers the production and preliminary testing of fiber optic sensors that contain a discrete array of analyte specific sensors on their distal ends. The development of the chemistries associated with this technology is covered elsewhere.
Date: November 1, 1994
Creator: Richards, J.B.; Brown, S.B.; Milanovich, F.P.; Healey, B.G.; Chadha, S. & Walt, D.R.
Partner: UNT Libraries Government Documents Department

Electrodissolution of electrodeposited iron oxides

Description: Galvanostatic reduction of ferric oxide was studied in phosphate solutions over a range of pH values. The oxides were prepared on gold by anodic electrodeposition from dilute ferrous borate solution. With increased pH, the potential of the reduction arrests decreased and the charge associated with the arrest increased. A dependence of -60 mV/pH was observed except between pH 7.5 and 8.5 where the slope approximated -180 mV/pH. Above pH 7.5 the slope was consistent with the thermodynamic predicted slope of -180 mV/pH expected from reductive dissolution of ferric oxide forming soluble ferrous ions. At higher pH values, a slope of -60 mV/pH has been accounted for by oxide reduction to form a solid lower valent oxide.
Date: December 31, 1996
Creator: Isaacs, H.S.; Ryan, M.P.; Kalonousky, D.N. & Virtanen, S.
Partner: UNT Libraries Government Documents Department

Consequence analysis of a NaOH solution spray release during addition to waste tank

Description: Toxicological consequences were calculated for a postulated maximum caustic soda (NaOH) solution spray leak during addition to a waste tank to adjust tank pH. Although onsite risk guidelines were exceeded for the unmitigated release, site boundary consequences were below the level of concern. Means of mitigating the release so as to greatly reduce the onsite consequences were recommended. Consequences for the mitigated release were estimated and both onsite and offsite consequences were found to negligible.
Date: October 9, 1996
Creator: Himes, D.A., Westinghouse Hanford Co.
Partner: UNT Libraries Government Documents Department

Exploring the conformational energy landscape of proteins

Description: Proteins possess a complex energy landscape with a large number of local minima called conformational substates that are arranged in a hierarchical fashion. Here we discuss experiments aimed at the elucidation of the energy landscape in carbonmonoxy myoglobin (MbCO). In the highest tier of the hierarchy, a few taxonomic substates exist. Because of their small number, these substates are accessible to detailed structural investigations. Spectroscopic experiments are discussed that elucidate the role of protonations of amino acid side chains in creating the substates. The lower tiers of the hierarchy contain a large number of statistical substates. Substate interconversions are observed in the entire temperature range from below 1 K up to the denaturation temperature, indicating a wide spectrum of energy barriers that separate the substates.
Date: April 1, 1997
Creator: Nienhaus, G.U.; Mueller, J.D. & McMahon, B.H.
Partner: UNT Libraries Government Documents Department

Chemical and isotopic variations of precipitation in the Los Alamos Region, New Mexico

Description: Precipitation collectors were installed at 14 locations on the Pajarito Plateau and surrounding areas to study variations in chemistry, stable isotopes and tritium for the years 1990 to 1993. The volume of precipitation was measured and samples were collected and analyzed every three to four months. All precipitation samples contain <2.50 mg/kg Cl and have pH values ranging from 5.4 to 6.7. The stable isotope ({delta}D/{delta}{sup 18}O) results record seasonal variations in precipitation as the weather patterns shift from sources in the Pacific Ocean to sources in the Gulf of Mexico. The stable isotope results also show isotopic variations due to elevation differences among the collection points. The tritium contents ({sup 3}H) in rain samples vary from 6.54 T.U. to 141 T.U. Contouring of high tritium values (e.g. >20 T.U.) from each collection period clearly shows that Laboratory activities release some tritium to the atmosphere. The effect of these releases are well below the limits set by the Environmental Protection Agency for drinking water (about 6200 T.U.). The magnitude of the releases is apparently greatest during the summer months. However, anomalous tritium values are detected as far north as Espahola, New Mexico for many collection periods. Tritium releases by the Laboratory are not constant; thus, the actual amount of tritium in each release has been diluted in the composite samples of our three to four month collection periods.
Date: February 1, 1995
Creator: Adams, A.I.; Goff, F. & Counce, D.
Partner: UNT Libraries Government Documents Department

Patterned functional arrays by selective de-wetting

Description: Using a micro-Contact Printing ({mu}-CP) technique, substrates are prepared with patterns of hydrophilic, hydroxyl-terminated SAMS and hydrophobic methyl-terminated SAMS. Beginning with a homogeneous solution of silica, surfactant, ethanol, water, and functional silane, preferential ethanol evaporation during dip-coating, causes water enrichment and selective de-wetting of the hydrophobic SAMS. Correspondingly, film deposition occurs exclusively on the patterned hydrophilic SAMS. In addition, by co-condensation of tetrafunctional silanes (Si(OR){sub 4}) with tri-functional organosilanes ((RO){sub 3}Si(CH{sub 2}){sub 3}NH{sub 2}), the authors have selectively derived the silica framework with functional amine NH{sub 2} groups. A pH sensitive, micro-fluidic system was formed by further conjugation reactions with pH sensitive dye molecules.
Date: May 11, 2000
Creator: FAN,HONGYOU; DOSHI,DHAVAL; LU,YUNFENG & BRINKER,C. JEFFREY
Partner: UNT Libraries Government Documents Department

Dissolution of Oxide Films on Aluminum in Near Neutral Solutions

Description: Simple linear potentiodynamic cycling measurements have been made on abraded pure Al in borate, chromate, phosphate, sulfate and nitrate solutions. In borate and chromate solutions the currents continued to decrease with each subsequent cycle. In phosphate dissolution of the oxide takes place producing repetitive repeat curves. The current variations in borate and chromate were simulated using a high field conduction oxide growth model. Including oxide dissolution in the model simulated the phosphate behavior. Results in sulfate and nitrate solutions were more complex. The behavior in the sulfate solution was attributed to effects of sulfate the oxide/solution interface.
Date: October 17, 1999
Creator: Isaacs, Hugh S.; Xu, Feng & Jeffcoate, Carrol S.
Partner: UNT Libraries Government Documents Department

AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

Description: Ever-stringent environmental constraints dictate that future coal cleaning technologies be compatible with micron-size particles. This research program seeks to develop an advanced coal cleaning technology uniquely suited to micron-size particles, i.e., aqueous biphase extraction. The partitioning behaviors of hematite in the dextran (Dex)/Triton X-100 (TX100) and polyethylene glycol (PEG)/dextran systems were investigated and the effects of some ionic surfactants on solid partition were studied. In both biphase systems, the particles stayed in the bottom dextran-rich phase under all pH conditions. This behavior is attributable to the fact that the hydrophilic oxide particles prefer the more hydrophilic bottom phase. Also, the strong favorable interaction between dextran and ferric oxide facilitates the dispersion of the solids in the polysaccharide-rich phase. In the Dex/TX100 system, addition of sodium dodecylsulfate (SDS) or potassium oleate had no effect on the solid partition; on the other hand, addition of dodecyltrimethylammonium bromide (DTAB) transferred the particles to the top phase or interface at high pH values. In the PEG/Dex system, the preferred location of hematite remained the bottom phase in the presence of either SDS or DTAB. The effects of anionic surfactants on the partition behavior are attributable to the fact that they are not able to replace the strongly adsorbed polysaccharide layer on the ferric oxide surface. The results with the cationic surfactant are due to electrostatic interaction between the cationic surfactant and the charged surface of the solid particles. The difference in solids partitioning in the two systems is the result of the different distribution of DTAB in these systems. In the Dex/TX100 system, DTAB prefers the top surfactant-rich phase, while it concentrates in the bottom phase in the PEG/dextran system.
Date: June 30, 2001
Creator: Osseo-Asare, K. & Zeng, X.
Partner: UNT Libraries Government Documents Department

EFFECT OF ANION, PH, AND TEMPERATURE ON THE DISSOLUTION BEHAVIOR OF ALUMINUM OXIDE FILMS.

Description: The growth and dissolution behavior of oxide film on abraded pure Al has been investigated using cyclic polarization and has been found to be highly dependent on solution chemistry and temperature. The nature of the anions, borate, chromate, phosphate, and sulfate, at pH 3 to 11, and temperatures 0 to 60 C were examined. In near neutral solutions the dissolution behavior was greatly affected by each anion. In borate and chromate solutions at near neutral pH and room temperature, the currents continued to decrease with each subsequent cycle due to oxide thickening. In contrast, a significant rate of oxide dissolution occurred to produce reproducible repetitive curves during subsequent cycles in a phosphate and sulfate. Sulfate also produced a distinctly different mode during high field oxide growth. In increasing acidic (pH &lt; 4) or basic (pH &gt;9) solutions the oxide dissolution rate increased rapidly. The oxide dissolution rate was always enhanced with increasing temperature. At high pH (&gt;9) or elevated temperature (60 C), a current maximum was observed in chromate, due to a diffusion controlled monochromate ion enhanced dissolution reaction at the oxide/solution interface.
Date: September 2, 2001
Creator: LEE,H. & ISAACS,H.S.
Partner: UNT Libraries Government Documents Department

Interfacial characterization and analytical applications of chemically-modified surfaces

Description: The goal of this work is to explore several new strategies and approaches to the surface modification and the microscopic characterization of interfaces in the areas mainly targeting sensor technologies that are of interest to environmental control or monitoring, and scanning probe microscopies techniques that can monitor interfacial chemical reactions in real time. Centered on the main theme, four specific topics are presented as four chapters in this dissertation following the general introduction. Chapter 1 describes the development of two immobilization schemes for covalently immobilizing fluoresceinamine at cellulose acetate and its application as a pH sensing film. Chapter 2 investigates the applicability of SFM to following the base-hydrolysis of a dithio-bis(succinimidylundecanoate) monolayer at gold in situ. Chapter 3 studies the mechanism for the accelerated rate of hydrolysis of the dithio-bis(succinimidylundecanoate) monolayer at Au(111) surface. Chapter 4 focuses on the development of an electrochemical approach to the elimination of chloride interference in Chemical Oxygen Demand (COD) analysis of waste water. The procedures, results and conclusions are described in each chapter. This report contains the introduction, references, and general conclusions. Chapters have been processed separately for inclusion on the data base. 95 refs.
Date: February 23, 1998
Creator: Wang, J.
Partner: UNT Libraries Government Documents Department

Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane: Quarterly technical progress report 15, October 1-December 31, 1996

Description: This document is the fifteenth quarterly technical progress report under Contract No. DE-AC22-92PC921 `Development of Vanadium- Phosphate Catalysts for Methanol Production by Selective Oxidation of Methane` and covers the period October-December, 1996. Vanadium phosphate, vanadyl pyrophosphate specifically, is used commercially to oxidize butane to maleic anhydride and is one of the few examples of an active and selective oxidation catalyst for alkanes. In this project we are examining this catalyst for the methane oxidation reaction. Initial process variable and kinetic studies indicated that vanadyl pyrophosphate is a reasonably active catalyst below 5000{degrees}C but produces CO as the primary product, no formaldehyde or methanol were observed. A number of approaches for modification of the phosphate catalyst to improve selectivity have been tried during this project. During this quarter we have obtained surface areas of catalysts prepared with modified surface acidity. The results confirm the enhanced activity of two of the modified preparations in methanol conversion (a test reaction for surface acid sites). In previous work we noted no improvement in methane oxidation selectivity for these catalysts. Surface areas, surface analysis by XPS, and bulk analysis by ICP-AA have been obtained for vanadyl pyrophosphate promoted by Cr, Cu, and Fe. These data indicate that roughly one tenth of the surface metal atoms are promoter. A similar analysis was obtained for the bulk. Preliminary examination of binding energies suggests a slightly more reduced surface for the Cr and Fe promoted catalysts which exhibit a significant selectivity to formaldehyde in methane oxidation. A more detailed kinetic model has also been developed to aid in comparing the promoted catalysts and is discussed. Plans for the coming months are outlined.
Date: April 2, 1997
Creator: McCormick, R.L., Alptekin, G.O.
Partner: UNT Libraries Government Documents Department

Oceanic CO{sub 2} measurements for the WOCE hydrological survey in the Pacific Ocean; Shipboard alkalinity analyses during 1991 and 1992. Final technical report, February 1, 1992--July 31, 1994

Description: This research group contributed titration alkalinity analyses to transects of the WOCE Hydrological Survey during 1991 and 1992. The results have been transmitted to the Carbon Dioxide Information and Analysis Center (CDIAC) of the Department of Energy in a technical data report having two parts: Oceanic CO{sub 2} Measurements for the WOCE Hydrographic Survey of the Pacific Ocean, 1990--1991: Shipboard Analyses During 1991 and 1992, Part 1. Alkalinity Measurements on TUNES, Leg 3, 1991. Oceanic CO{sub 2} Measurements for the WOCE Hydrographic Survey of the Pacific Ocean, 1990--1991: Shipboard Analyses During 1991 and 1992, Part 2. Alkalinity Measurements on CGC92, Legs 1 and 2, 1992. This report contains a paper entitled, ``Total dissolved inorganic carbon measurements made on WOCE leg P13`` by Andrew G. Dickson. A brief description of how these measurements were made and calibrated has been provided along with a statement of the quality of the measurements. The data themselves have been sent to ORNL CDIAC for archival and distribution.
Date: July 1, 1998
Creator: Keeling, C.D.
Partner: UNT Libraries Government Documents Department

A Silica/Fly Ash-Based Technology for Controlling Pyrite Oxidation

Description: The purpose of our studies during this past six-month period was to evaluate the surface properties of iron-oxide-silicate coatings. The specific objectives were (a) to evaluate the mechanisms and ability of hydrous ferric oxide (HFO) to adsorb silica (Si); (b) to evaluate the effects of Si on the bulk and surface properties of HFO; and (c) to evaluate the effect of Si on heavy-metal adsorption properties by iron-oxides.
Date: April 14, 1997
Creator: Evangelou, V. P.
Partner: UNT Libraries Government Documents Department