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in subjects: "Surface Area"

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Dispersion aspects of silicon carbide gelcasting

The principal objective of this research was to increase the solid loading of silicon carbide (SiC) powder, in an appropriate liquid medium, to a level that is useful for gelcasting technology. A number of factors that determine the maximum concentration of silicon carbide that can be incorporated into a pourable ceramic suspension have been identified. The pH of the system is the most critical processing parameter. Its proper adjustment (pH 11 to 13) allows SiC concentrations exceeding 50%, ba… more

Date: September 1, 1991

Creator: Bleier, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A novel process for methanol synthesis

A bench-scale reactor is being used to conduct studies of the conversion of synthesis gas to methanol by a novel process. During the last quarter, we provided evidence for a two step reaction in series as against the direct hydrogenation of CO. We believe that the carbonylation reaction takes place in the liquid phase adjacent to the solid catalyst surface while the hydrogenolysis reaction is restricted to the surface of Cu-chromite. A non-equilibrium film model was proposed to explain the unex… more

Date: January 1, 1991

Creator: Tierney, J.W. & Wender, I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Surface areas by positron annihilation spectroscopy

Positron annihilation spectroscopy (PAS) is a technique for measuring the length of time that a positron exists after being injected into a specific material. Lifetime measurements have been used for studying defects in metals. These imperfections affect the localized electron densities which in turn influence the lifetime of the positron before annihilation occurs. Electron density differences are also associated with surfaces. This paper describes the PAS technique and shows a correlation bet… more

Date: January 1, 1985

Creator: Dale, J.M.; Rosseel, T.M.; Hulett, L.D.; Venkateswaran, K.; Jean, Y.C. & Fuller, E.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fundamental mechanisms in flue gas conditioning

This project is divided into four tasks. The Management Plan was developed in task 1. Task 2, Evaluation of Mechanisms in FGD Sorbent and Ash Interactions, focuses on the characteristics of binary mixtures of these distinct powders. Task 3, Evaluation of Mechanisms in Conditioning Agents and Ash, is designed to examine the effects of various conditioning agents on fine ash particles to determine the mechanisms by which these agents alter the physical properties of the ash. Tasks 2 and 3 began w… more

Date: April 27, 1992

Creator: Snyder, T. R.; Robinson, M. S. & Bush, P. V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Droplet size characteristics and energy input requirements of emulsions formed using high-intensity-pulsed electric fields

Experimental methods have been developed to measure droplet size characteristics and energy inputs associated with the rupture of aqueous droplets by high-intensity-pulsed electric fields. The combination of in situ microscope optics and high-speed video cameras allows reliable observation of liquid droplets down to 0.5 ..mu..m in size. Videotapes of electric-field-created emulsions reveal that average droplet sizes of less than 5 ..mu..m are easily obtained in such systems. Analysis of the ene… more

Date: January 1, 1987

Creator: Scott, T.C. & Sisson, W.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The physical properties of microcellular composite foams

Recently we reported on a method of preparing microcellular composite foams. In this procedure an open-celled polystyrene foam is prepared by the polymerization of a high-internal-phase water-in-oil emulsion containing styrene, divinylbenzene, surfactant, free-radial initiator and water. After drying, the cells of the polystyrene foam are then filled with other materials such as aerogel or resoles. The physical properties of these materials, e.g., surface area, density, thermal conductivity, an… more

Date: January 1, 1989

Creator: Nyitray, A.M.; Williams, J.M.; Onn, D.; Witek, A. (Los Alamos National Lab., NM (USA) & Delaware Univ., Newark, DE (USA). Applied Thermal Physics Lab.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Local phase distribution and interfacial area in a horizontal bubbly two-phase flow

No Description Available.

Date: January 1, 1991

Creator: Kocamustafaogullari, G.; Huang, W.D. & Wang, Z.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Metal toxicity evaluation of Savannah River Plant saltstone comparison of EP and TCLP test results

Saltstone is the waste treatment and disposal concept for low-level defense waste at the Savannah River Plant. The waste is a sodium salt solution which has about 230 ..mu..CiL in addition to the hazardous characteristics of corrosivity and metal toxicity (Cr/sup +6/ > 100 ppM). Two EPA test procedures are routinely used at SRP to evaluate metal toxicity of wastes and wasteforms. 1) the Extraction Procedure (EP); and 2) the Toxicity Characterization Leaching Procedure (TCLP). The EP test is … more

Date: January 1, 1988

Creator: Langton, C A

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Strain Induced Phenomena in Ca(OH)/sub 2/ Made by Reaction of CaO with Water Vapor

Three physically distinguishable, poorly crystalline forms of Ca(OH)/sub 2/ which are made by reactions of water vapor at 25/sup 0/C with CaO powders evolve heat and develop sharper x-ray diffraction patterns when heated to 300/sup 0/C. Measurements of x-ray diffraction peak line breadths, surface areas, porosities, and pore size distributions were made before and after heat treatment. The exothermic process of the one of these forms of Ca(OH)/sub 2/ which is nonporous is recrystallization of t… more

Date: January 1, 1980

Creator: Beruto, D.; Searcy, A. W.; Barco, L. & Belleri, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Methods for determining radionuclide retardation factors: status report

This report identifies a number of mechanisms that retard radionuclide migration, and describes the static and dynamic methods that are used to study such retardation phenomena. Both static and dynamic methods are needed for reliable safety assessments of underground nuclear-waste repositories. This report also evaluates the extent to which the two methods may be used to diagnose radionuclide migration through various types of geologic media, among them unconsolidated, crushed, intact, and frac… more

Date: April 1, 1980

Creator: Relyea, J. F.; Serne, R. J. & Rai, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Studies in Coal Liquefaction With Application to the SRC and Related Processes. Quarterly Report, May-July 1983

This report examines liquid-phase adsorption as a possible method of studying the interactions between coal liquids and hydrotreating catalysts. The duel purposes of this work are to develop a method to determine specific surface areas of porous catalysts and to examine how compounds commonly found in coal liquids are adsorbed on hydrotreating catalysts. The liquid-phase adsorption studies were performed at room temperature in tubing bomb reactors. Adsorption isotherms obtained from these exper… more

Date: March 1, 1984

Creator: Tarrer, A. R.; Guin, J. A. & Curtis, C. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-… more

Date: February 23, 1987

Creator: Jha, M. C. & Baltich, L. K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The role of test parameters on the kinetics and thermodynamics of glass leaching. [None]

The relative durabilities of nuclear waste, natural, and ancient glasses have been assessed by standard laboratory leach tests. Different test conditions result in different glass surface areas (SA), leachant volumes (V), and test durations (t). Leachate concentrations are known to be a parabolic function of the kinetic test parameter SAV/center dot/t. Based on durability experiments of glass monoliths at low (SAV)/center dot/ glass durability has been shown to be a logarithmic function of the … more

Date: January 1, 1988

Creator: Jantzen, Carol M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Paleoclimatic significance of lake level fluctuations in the Lahontan Basin. [Pyramid Lake, Nevada]

An energy flux balance model has been developed which treats evaporation as a function of air temperature, surface water temperature, precipitable water aloft, the amount, height, and type of sky cover, and the optical air mass. The model has been used to estimate the mean historical evaporation rate for Pyramid Lake, Nevada, using as input climatic data from the Reno area averaged over the period 1950 to 1975. Estimated and measured values of the mean annual evaporation rate were found to be i… more

Date: August 1, 1980

Creator: Benson, L. V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Specific surface area behavior of a dissolving population of particles. Augmenting Mercer Dissolution Theory

Specific surface area (Sp) measurements were made on two uranium oxide aerosol materials before and after in vitro dissolution studies were performed on the materials. The results of these Sp measurements were evaluated relative to predictions made from extending Mercer dissolution theory to describe the Sp behavior of a dissolving population of particles.

Date: January 1, 1986

Creator: Scripsick, R.C. & Rothenberg, S.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A comparison of glass reaction at high and low SA/V: PCT vs MCC-1

Leach tests have been performed at surface area/volume (SA/V) of 10, 2000, and 20,000 m{sup {minus}1} using actinide-doped borosilicate waste glass (SRL 131 and SRL 202) to assess the effects of the SA/V on the mechanism and rate of the glass reaction. Solution results are presented which show the major effect of the SA/V to be dilution. Higher SA/V result in higher leachate pH values being attained due to initial ion exchange reactions. The higher pH values then accelerate hydrolysis of the gl… more

Date: January 1, 1992

Creator: Ebert, W.L. & Bates, J.K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

SOEC efficiency and cost improvement Part 1 and 2.

Part I: Electrochemical and X-ray Characterization of Solid-Oxide Electrolysis Cell Oxygen Electrodes on Electrolyte Substrates--The governing reaction mechanisms, and the electrode and electrolyte material compositions and structures, that controls the efficiency and durability of the solid oxide electrolysis cells (SOEC) need to be identified and well-understood for a significant improvement in nuclear hydrogen production using high temperature steam electrolysis. ANL conducted experimental a… more

Date: June 20, 2007

Creator: Yildiz, B.; Chang, K.-C.; Meyers, D. J.; You, H.; Carter, J. D.; Elam, J. W. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Development of a CO2 Sequestration Module by Integrating Mineral Activation and Aqueous Carbonation

Mineral carbonation is a promising concept for permanent CO{sub 2} sequestration due to the vast natural abundance of the raw materials and the permanent storage of CO{sub 2} in solid form as carbonates. The sequestration of CO{sub 2} through the employment of magnesium silicates--olivine and serpentine--is beyond the proof of concept stage. For the work done in this project, serpentine was chosen as the feedstock mineral due to its abundance and availability. Although the reactivity of olivine… more

Date: August 14, 2006

Creator: Alexander, George; Aksoy, Parvana; Andresen, John; Maroto-Valer, Mercedes & Schobert, Harold

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Mineralization of Radioactive Wastes by Fluidized Bed Steam Reforming (FBSR): Comparisons to Vitreous Waste Forms, and Pertinent Durability Testing

The Savannah River National Laboratory (SRNL) was requested to generate a document for the Washington State Department of Ecology and the U.S. Environmental Protection Agency that would cover the following topics: (1) A description of the mineral structures produced by Fluidized Bed Steam Reforming (FBSR) of Hanford type Low Activity Waste (LAW including LAWR which is LAW melter recycle waste) waste, especially the cage structured minerals and how they are formed. (2) How the cage structured mi… more

Date: December 26, 2008

Creator: Jantzen, Carol M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Final Scientific Report : Development of Transition Metal/ Chalcogen Based Cathode Catalysts for PEM Fuel Cells

The aim of this project was to investigate the potential for using base metal sulfides and selenides as low cost replacements for precious metal catalysts, such as platinum, currently being used in PEM fuel cells. The approach was to deposit thin films of the materials to be evaluated onto inert electrodes and evaluate their activity for the cathode reaction (oxygen reduction) as well as ex-situ structural and compositional characterization. The most active materials identified are CoS2 and the… more

Date: February 29, 2008

Creator: Campbell, Stephen, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

SAVANNAH RIVER SITE TANK 18 AND TANK 19 WALL SAMPLER PERFORMANCE

A sampling tool was required to evaluate residual activity ({mu}Curies per square foot) on the inner wall surfaces of underground nuclear waste storage tanks. The tool was required to collect a small sample from the 3/8 inch thick tank walls. This paper documents the design, testing, and deployment of the remotely operated sampling device. The sampler provides material from a known surface area to estimate the overall surface contamination in the tank prior to closure. The sampler consisted of … more

Date: December 19, 2009

Creator: Leishear, R.; Thaxton, D.; Minichan, R.; France, T.; Steeper, T.; Corbett, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

PEMFC reconfigured anodes for enhancing CO tolerance with air bleed.

Practical PEM fuel cells based on perfluorinated ionomer membranes (eg Nafion), most probably will use reformed fuel as primary source for the anode feed. The reformate, besides hydrogen, may contain trace amounts of carbon monoxide (CO. from a few to hundreds ppm), whose presence is detrimental to the cell performance. Energy conversion at fuel cells depends on highly dispersed carbon-supported Pt, where the hydrogen electro-oxidatisn takes place. However, CO strongly adsorbs on the Pt surface… more

Date: January 1, 2001

Creator: Uribe, F. J. (Francisco J.) & Zawodzinski, T. A. (Thomas A.), Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Characterization of impact fracture of brittle solid-waste forms

This paper presents a methodology for analyzing particle size distributions obtained in impact testing of brittle waste-form materials. The methodology includes (a) a linear two-parameter lognormal correlation of the weight fraction less than any given size, (b) a mathematical function of the two lognormal parameters to determine the total surface area in terms of a dimensionless shape factor, and (c) a surface-energy constant to predict the anticipated increase of surface area from the known e… more

Date: January 1, 1979

Creator: Mecham, W. J.; Jardine, L. J.; Pelto, R. H. & Steindler, M. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Waste isolation safety assessment program. Task 4. Collection and generation of transport data theoretical and experimental evaluation of waste transport in selected rocks. Annual progress report, October 1, 1978-September 30, 1979

The objective of the program is to establish a basis for the prediction of radionuclide sorption in geologic environments. In FY 79, experimental and theoretical efforts were concentrated on a study of the sorption of cesium on the solid substrates Min-u-sil (quartz) and Belle Fourche clay (montmorillonite). Cesium sorption isotherms were obtained for the two substrates at 26/sup 0/C as a function of initial Cs concentration in solution (10/sup -3/M to 10/sup -9/M), pH (5 to 10) and supporting … more

Date: September 30, 1979

Creator: Silva, R. J.; Benson, L. V.; Yee, A. W. & Parks, G. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department