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Isopiestic Determination of the Osmotic and Activity Coefficients of Li2SO4(aq) at T = 298.15 and 323.15 K, and Representation with an Extended Ion-interaction (Pitzer) model

Description: Isopiestic vapor-pressure measurements were made for Li{sub 2}SO{sub 4}(aq) from 0.1069 to 2.8190 mol {center_dot} kg{sup -1} at 298.15 K, and from 0.1148 to 2.7969 mol {center_dot} kg{sup -1} at 323.15 K, with NaCl(aq) as the reference standard. Published thermodynamic data for this system were reviewed, recalculated for consistency, and critically assessed. The present results and the more reliable published results were used to evaluate the parameters of an extended version of Pitzer's ion-interaction model with an ionic-strength dependent third virial coefficient, as well as those of the standard Pitzer model, for the osmotic and activity coefficients at both temperatures. Published enthalpies of dilution at 298.15 K were also analyzed to yield the parameters of the ion-interaction models for the relative apparent molar enthalpies of dilution. The resulting models at 298.15 K are valid to the saturated solution molality of the thermodynamically stable phase Li{sub 2}SO{sub 4} {center_dot} H{sub 2}O(cr). Solubilities of Li{sub 2}SO{sub 4} {center_dot} H{sub 2}O(cr) at 298.15 K were assessed, and the selected value of m(sat.) = 3.13 {+-} 0.04 mol {center_dot} kg{sup -1} was used to evaluate the thermodynamic solubility product K{sub s}(Li{sub 2}SO{sub 4} {center_dot} H{sub 2}O, cr, 298.15 K) = (2.62 {+-} 0.19) and a CODATA-compatible standard molar Gibbs energy of formation {Delta}{sub f}G{sub m}{sup o} (Li{sub 2}SO{sub 4} {center_dot} H{sub 2}O, cr, 298.15 K) = -(1564.6 {+-} 0.5) kJ {center_dot} mol{sup -1}.
Date: January 3, 2007
Creator: Rard, J A; Clegg, S L & Palmer, D A
Partner: UNT Libraries Government Documents Department

Phase Behavior of Aqueous NA-K-MG-CA-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

Description: A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems.
Date: September 14, 2006
Creator: Gruszkiewiez, M.S.; Palmer, D.A.; Springer, R.D.; Wang, P. & Anderko, A.
Partner: UNT Libraries Government Documents Department

OSMOTIC COEFFICIENTS, SOLUBILITIES, AND DELIQUESCENCE RELATIONS IN MIXED AQUEOUS SALT SOLUTIONS AT ELEVATED TEMPERATURE

Description: While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl{sub 2}, LiCl, and NaCl used as references, precise direct-pressure measurements were also made at elevated temperatures. The project included multicomponent mixtures ...
Date: February 22, 2006
Creator: Gruszkiewicz, M.S. & Palmer, D.A.
Partner: UNT Libraries Government Documents Department

Solubility and Surface Adsorption Characteristics of Metal Oxides to High Temperature

Description: The interaction of high temperature aqueous solutions with mineral surfaces plays a key role in many aspects of fossil, geothermal and nuclear energy production. This is an area of study in which the subsurface geochemical processes that determine brine composition, porosity and permeability changes, reservoir integrity, and fluid flow rates overlap with the industrial processes associated with corrosion of metal parts and deposition of solids in pipes and on heat exchanger surfaces. The sorption of ions on mineral surfaces is also of great interest in both the subsurface and ''above ground'' regimes of power production, playing a key role in subsurface migration of contaminants (nuclear waste disposal, geothermal brine re-injection, etc.) and in plant operations (corrosion mitigation, migration of radioactive metals from reactor core to heat exchanger, etc.). In this paper, results of the solubility and surface chemistry of metal oxides relevant to both regimes are summarized.
Date: May 4, 2001
Creator: Wesolowski, D.J.; Machesky, M.L.; Ziemniak, S.E.; Xiao, C.; Palmer, D.A.; Anovitz, L.M. et al.
Partner: UNT Libraries Government Documents Department

Solubility and Reaction Rates of Aluminum Solid Phases Under Geothermal Conditions

Description: Experimental studies involving equilibrium solubility and dissolution/precipitation rates were initiated on aluminum hydroxide phases prevalent under geothermal reservoir conditions. A large capacity, hydrogen-electrode concentration cell (HECC) was constructed specifically for this purpose.
Date: May 28, 2000
Creator: Benezeth, P.; Palmer, D.A.; Wesolowski, D.J. & Anovitz, L.M.
Partner: UNT Libraries Government Documents Department

Solubility and Reaction Rates of Aluminum Solid Phases Under Hydrothermal Conditions

Description: Experimental studies involving equilibrium solubility and dissolution/precipitation rates were initiated on boehmite (AIOOH) using a hydrogen-electrode concentration cell (HECC). This cell provides continuous, accurate in situ pH measurements of solid/solution mixtures to 295 C with provision for either removing solution samples for analysis of the metal content, or adding either of two titrants. This cell has been recently used to measure the solubility of minerals such as brucite; boehmite, zincite, arid magnetite. The ability to perturb pH, isothermally by addition of acidic or basic titrant opens the door for studies of the kinetics of dissolution/precipitation, even for relatively fast reactions. By monitoring the change in pH, with time, detailed kinetic information can be obtained without the need for sampling.
Date: November 14, 1999
Creator: Benezeth, P.; Palmer, D.A. & Wesolowski, D.
Partner: UNT Libraries Government Documents Department

A Flow-Through High-Pressure Electrical Conductance Cell for Determining of Ion Association of Aqueous Electrolyte Solutions at High Temperature and Pressure

Description: A flow-through high-pressure electrical conductance cell was designed and constructed to measure limiting molar conductances and ion association constants of dilute aqueous solutions with high precision at high temperatures and pressures. The basic concept of the cell employs the principle developed at the University of Delaware in 1995, but overall targets higher temperatures (to 600 C) and pressures (to 300 MPa). At present the cell has been tested by measuring aqueous NaCl and LiOH solutions (10{sup {minus}3} to 10{sup {minus}5} mol.kg{sup {minus}1}) to 405 C and 33 MPa with good results.
Date: September 12, 1999
Creator: Bianchi, H.; Ho, P.C.; Palmer, D.A. & Wood, R.H.
Partner: UNT Libraries Government Documents Department

Microstructural Characterization of Water-Rich Boehmite (AlO(OH)): TEM Correlation of Apparently Divergent XRD and TGA Results

Description: An understanding of the solid-phase thermodynamics and aqueous speciation of aluminum is critical to our ability to understand and predict processes in a wide variety of geologic and industrial settings. Boehmite (AIO(OH)) is an important phase in the system Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O that has been the subject of a number of structural and thermodynamic studies since its initial synthesis [l] and discovery in nature [2]. Unfortunately, it has long been recognized that thermogravimetric analysis (TGA) of both synthetic and natural boehmite samples (that appear well crystallized by powder XRD methods) yields significant excess water - typically losing 16-16.5 wt. % on heating as compared with a nominal expected weight loss of 15.0 wt. % [3,4]. The boehmite used in our experiments was synthesized hydrothermally from acid-washed gibbsite (Al(OH)<suv>3</sub>) at 200°C. Powder XRD and SEM examination showed no evidence of the presence a contaminant phase. The TGA patterns do not suggest that this is due to adsorbed water, so a structural source is likely. We therefore undertook to examine this material by TEM to clarify this phenomenon.
Date: August 1999
Creator: Allard, L. F.; Anovitz, L. M.; Benezeth, P.; Coffey, D. W.; Palmer, D. A.; Porter, W. D. et al.
Partner: UNT Libraries Government Documents Department

The Partitioning of Acetic, Formic, and Phosphoric Acids Between Liquid Water and Steam

Description: The chemical carryover of impurities and treatment chemicals from the boiler to the steam phase, and ultimately to the low-pressure turbine and condenser, can be quantified based on laboratory experiments preformed over ranges of temperature, pH, and composition. The two major assumptions are that thermodynamic equilibrium is maintained and no deposition, adsorption or decomposition occurs. The most recent results on acetic, formic and phosphoric acids are presented with consideration of the effects of hydrolysis and dimerization reactions. Complications arising from thermal decomposition of the organic acids are discussed. The partitioning constants for these acids and other solutes measured in this program have been incorporated into a simple thermodynamic computer code that calculates the effect of chemical and mechanical carryover on the composition of the condensate formed to varying extents in the water/steam cycle.
Date: June 22, 1999
Creator: Gruszkiewicz, M. S.; Marshall, S. L.; Palmer, D. A. & Simonson, J. M.
Partner: UNT Libraries Government Documents Department

Geochemistry of Aluminum in High Temperature Brines

Description: The objective ofthis research is to provide quantitative data on the equilibrium and thermodynamic properties of aluminum minerals required to model changes in permeability and brine chemistry associated with fluid/rock interactions in the recharge, reservoir, and discharge zones of active geothermal systems. This requires a precise knowledge of the thermodynamics and speciation of aluminum in aqueous brines, spanning the temperature and fluid composition rangesencountered in active systems. The empirical and semi-empirical treatments of the solubility/hydrolysis experimental results on single aluminum mineral phases form the basis for the ultimate investigation of the behavior of complex aluminosilicate minerals. The principal objective in FY 1998 was to complete the solubility measurements on boehmite (AIOOH) inNaC1 media( 1 .O and 5.0 molal ionic strength, IOO-250°C). However, additional measurements were also made on boehmite solubility in pure NaOH solutions in order to bolster the database for fitting in-house isopiestic data on this system. Preliminary kinetic Measurements of the dissolution/precipitation of boehmite was also carried out, although these were also not planned in the earlier objective. The 1999 objectives are to incorporate these treatments into existing codes used by the geothermal industry to predict the chemistry ofthe reservoirs; these calculations will be tested for reliability against our laboratory results and field observations. Moreover, based on the success of the experimental methods developed in this program, we intend to use our unique high temperature pH easurement capabilities to make kinetic and equilibrium studies of pH-dependent aluminosilicate transformation reactions and other pH-dependent heterogeneous reactions.
Date: May 18, 1999
Creator: Benezeth, P.; Palmer, D. A. & Wesolowski, D. J.
Partner: UNT Libraries Government Documents Department

Measurements of the Distribution of Solutes between Liquid Water and Steam

Description: Direct measurements of the concentration of solutes in both liquid and steam phases in equilibrium with each other have been made in a static mode utilizing a platinum-lined autoclave to a maximum of 350 deg C. Partitioning constants were derived from these measurements based on existing experimental or estimated values of the stoichiometric mean activity coefficients for the solutes in the liquid phase. Independent measurements of the conductance of some of the solutes in dilute aqueous solutions to 600 deg C and 300MPa were also made. The combined results are discussed in terms of a speciated model and the implications of these results to industrial and natural hydrothermal processes are presented. PARTITIONING CONSTANT, ION-ASSOCIATION, CONDUCTIVITY, SPECIATION, CORROSION.
Date: December 31, 1997
Creator: Palmer, D.A.; Simonson, J.M. & Ho, P.C.
Partner: UNT Libraries Government Documents Department

Solubility of, and hydrogen ion adsorption on, some metal oxides in aqueous solutions to high temperatures

Description: Solubility of boehmite (AlOOH), ferrous hydroxide (Fe(OH)2)/magnetite (Fe3O4), zincite (ZnO), and brucite (Mg(OH)2) were measured over a range of temperatures (AlOOH, 100-290 C; Fe(OH)2/Fe3O4, 100-250 C; ZnO, 50-290 C; Mg(OH)2, 60-200 C) using in situ pH measurements. A hydrogen-electrode concentration cell was used; the pH range depended on the oxide. The solubility results for boehmite mainly demonstrate the method viability, while those for zincite are mainly restricted to mildly acidic to neutral pH where Zn{sup 2+} predominates in solution. The magnetite (presumably coated with Fe(OH)2) solubilities extend from pHs > 5 and, because of relevance to water/steam cycles of power plants, are compared in detail with previous studies. The same cell was used to investigate the surface adsorption-desorption thermodynamics of H ions on rutile (TiO2) and zincite to 290 C. Behavior of pH at zero-point-of-charge as function of temperature and application of the Stern-3-layer model were determined for this solid. The zincite study is still incomplete; preliminary results show trends that can be rationalized only qualitatively now with the zero- point-of-charge being apparently affected by hydration of the surface in basic solutions and specific adsorption of Na ions under the same conditions.
Date: August 1, 1997
Creator: Palmer, D.A.; Benezeth, P.; Wesolowski, D.J.; Anovitz, L.M.; Machesky, M.L.; Hayashi, Ken-ichiro et al.
Partner: UNT Libraries Government Documents Department

Volatility of HCl and the thermodynamics of brines during brine dryout

Description: Laboratory measurements of liquid-vapor partitioning (volatility) of chlorides from brines to steam can be used to indicate the potential for corrosion problems in geothermal systems. Measurements of volatilities of solutes in chloride brines have established a possible mechanism for the production of high-chloride steam from slightly acidic high temperature brines. Questions concerning the fate of NaCl in the steam production process have been addressed through extensive measurements of its volatility from brines ranging in concentration from dilute solutions to halite saturation. Recent measurements of chloride partitioning to steam over brines in contact with Geysers rock samples are consistent with our concept of the process for production of high-chloride steam.
Date: April 1, 1997
Creator: Simonson, J.M. & Palmer, D.A.
Partner: UNT Libraries Government Documents Department

Solvent extraction of cesium by substituted crown ethers

Description: The extraction of alkali metal nitrates by 18-crown-6, 21-crown-7, and 24-crown-8 ethers, bearing cyclohexano, benzo-, t-alkylbenzo, and furano- substituents, in 1,2-dichloroethane has been surveyed. Introduction of a furano substituent onto the macrocyclic ring of 18-crown-6 or 21 crown-7 ethers causes a significant reduction in both extraction efficiency and selectivity. Addition of an additional benzo group to dibenzo-21 -crown-7, to give tribenzo-21 -crown-7, decreases both extraction efficiency and selectivity, whereas addition of one or two additional benzo groups to dibenzo-24-crown-8 increases the extraction efficiency and selectivity for the larger ions Rb+ and Cs{sup +} Detailed equilibrium modeling of the extraction by lipophilic 21 -crown-7 ethers indicates that the addition of t-alkyl substituents onto the benzo groups has only a minor effect on the extraction of cesium nitrate by dibenzo-21 -crown-7 ethers.
Date: December 31, 1996
Creator: Sachleben, R.A.; Deng, Y.; Palmer, D.A. & Moyer, B.A.
Partner: UNT Libraries Government Documents Department

Volatility of copper

Description: The relevant aqueous thermodynamics of copper and its oxides are evaluated and summarized with emphasis on solubility, hydrolysis, and complexation. The solubilities of metallic copper, solid cuprous and cupric oxides in steam measured by Pocock and Stewart in 1963 are discussed and the latter data are fitted in the form of established empirical equations and compared to other existing results. No other sources of data were found for the solubility of copper and cupric oxide in steam and even these data are very limited. Discussion of corresponding available solubility data on both oxide phases in liquid water is given. The possible effects of complexing agents are considered. A brief discussion is provided of the role of surface adsorption in determining the fate of dissolved copper in the boiler. 37 refs., 5 figs., 3 tabs.
Date: August 1, 1996
Creator: Palmer, D. A.; Simonson, J. M. & Joyce, D. B.
Partner: UNT Libraries Government Documents Department

The aqueous chemistry of aluminum: A new approach to high temperature solubility measurements

Description: The solubility of boehmite, AlO(OH), has been measured as a function of pH (2-10, depending on ionic strength) temperature (100- 250{degrees}C) and ionic strength (0.03-1 molal, NaCl) in a hydrogen- electrode concentration cell, HECC, which provided in situ measurement of hydrogen ion molality. Samples of the solution were withdrawn after the pH reading stabilized for analysis of total aluminum content by ion chromatography. Acidic or basic titrant could then be metered into the cell to affect a change in the pH of the solution. The direction of approach to the equilibrium saturated state could be readily varied to ensure that the system was reversible thermodynamically. This represents our second application of direct pH measurement to high temperature solubility studies. The results as low ionic strength are compared with those from two recently-reported high-temperature studies of boehmite solubility, which relied on the conventional batch technique. Comparisons are also made with the low temperature (<90{degrees}C) hydrolysis constants for aluminum garnered from solubility measurements with gibbsite as the stable phase. Based on these preliminary results, it is possible to draw some general conclusions concerning the relative importance of the aluminum species in solution and to reduce significantly the number of experiments needed to define this complex system in a thermodynamic sense.
Date: January 1, 1996
Creator: Palmer, D.A.; Wesolowski, D.J. & Benezeth, P.
Partner: UNT Libraries Government Documents Department

Experimental studies in high temperature aqueous chemistry at Oak Ridge National Laboratory

Description: Experimental research is conducted and models developed in a long- standing program at Oak Ridge on aqueous chemistry at high temperatures of broad classes of electrolytes emphasizing thermodynamics of reaction equilibria and excess thermodynamic properties of electrolytes. Experimental methods, their capabilities, data analysis, and results are summarized. Relevance of the work to problems in power plants, natural and industrial processes as well as basic solution chemistry and geochemistry are given. Progress in potentiometry, electrical conductivity, flow calorimetry, and isopiestic research is described. Future in this field demands greater precision in measurements and significant gains in our understanding of the solvation phenomena especially in the vicinity and beyond the critical point for water. The communities who do research on scattering, spectroscopy, and computer simulations can help guide these efforts through studies at extreme conditions.
Date: January 1, 1996
Creator: Mesmer, R.E.; Palmer, D.A.; Simonson, J.M.; Holmes, H.F.; Ho, P.C.; Wesolowski, D.J. et al.
Partner: UNT Libraries Government Documents Department

Measurement and control of pH in hydrothermal solutions

Description: Hydrogen-electrode concentration cells with liquid junction are routinely used to measure the pH of aqueous solutions from 0 to 300 C. Results include the dissociation constants of common acids and bases and the hydrolysis and complexation of metal ions in aqueous electrolytes over a wide range of salinities. Recently, we have utilized these cells to examine the sorption of H{sup +} on mineral surfaces, the solubility of minerals with continuous in situ pH measurement, and the thermal decompositon rates of organic acids.
Date: December 31, 1995
Creator: Wesolowski, D.J.; Palmer, D.A. & Mesmer, R.E.
Partner: UNT Libraries Government Documents Department

Electrical conductivity measurements of aqueous boric acid at 25--350{degree}C at saturation vapor pressure. Final report

Description: Electrical conductance measurements of aqueous boric acid solutions (15-110 g/kg-H{sub 2}O {equivalent_to} 0.251--1.815 mol/kg-H{sub 2}O) were measured over the temperature range 25 to 75 C at saturation vapor pressures in glass cells with parallel platinum electrodes. Sixteen series of measurements were made involving three samples of boric acid from different sources. Conductance measurements were also made at 15.5 and 30.5 g/kg-H{sub 2}O over the temperature range 100 to 350 C at 50 C intervals with a metallic cell fitted with concentric platinum electrodes. The specific conductances of H{sub 3}BO{sub 3} (aq)were calculated after correction for the conductance of the solvent (water) and are tabulated in this report. At the specific conditions requested in the project description, namely a concentration of 110 g/kg-H{sub 2}O and 65 C, the specific conductance of boric acid is 293.2 {+-} 1.8 microSiemens/cm based on duplicate measurements of four independent solutions. The results from these tests will be utilized by the Tokamak Physics Experimental Project (TPX).
Date: September 1, 1995
Creator: Ho, P.C. & Palmer, D.A.
Partner: UNT Libraries Government Documents Department

Ion-association: Models and thermodynamics

Description: Association reactions are an important class for probing ion-water and water-water interactions. A review of some earlier results led to a model of ion-association reactions discussed by Mesmer et al. in Activity Coefficients of Electrolyte Solutions in 1991. Additional results especially from electrical conductance studies on acids and salts will be discussed. There is mounting evidence consistent with the general observations regarding the temperature and pressure dependencies for thermodynamic quantities for association reactions seen earlier including the driving force, T{Delta}S, that originates from the release of ion hydrate waters when pairing occurs. The density model for log K{sub A} serves well as a simple representation of the strong variation with temperature and pressure seen for these reactions. The decrease in solvent structure with increasing temperature and the increasing range of the ion-dipole interactions for hydrated ions (with decreasing dielectric constant) are thought to be the principal factors accounting for the dramatic trends seen for the thermodynamic quantities. Some discussion will be given of the simplicity found for the T-P dependencies for {delta}U{sub v} and {delta}C{sub v}, the changes in internal energy and heat capacity on a constant volume basis.
Date: July 1, 1995
Creator: Mesmer, R.E.; Ho, P.C.; Holmes, H.F.; Palmer, D.A. & Simonson, J.M.
Partner: UNT Libraries Government Documents Department