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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

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

Hydrolysis of iodine: equilibria at high temperatures

Description: The hydrolysis (or disproportionation) of molecular iodine to form iodate and iodide ions has been studied by emf measurements over the temperature range, 3.8/sup 0/ to 209.0/sup 0/C. The interpretation of these results required a knowledge of the formation constant for triiodide ion and the acid dissociation constant of iodic acid, both of which were measured as a function of temperature. The resulting thermodynamic data have been incorporated into a general computer model describing the hydrolysis equilibria of iodine as a function of initial concentration, pH and temperature.
Date: January 1, 1984
Creator: Palmer, D.A.; Ramette, R.W. & Mesmer, R.E.
Partner: UNT Libraries Government Documents Department

A potentiometric study of the hydrolysis of ethylenediaminetetraacetic acid to 150{degrees}C

Description: Ethylenediaminetetraacetate anions, EDTA{sup 4-}, were titrated in a hydrogen-electrode concentration cell with an acidic titrant from 0 to 150{degrees}C at 25{degrees}C intervals. These titrations were carried out in the presence of 0. 1, 0.2, and 1.0 mol{center_dot}kg{sup -1} with the supporting electrolytes, sodium chloride, NaCl, and 1.0 mol{center_dot}kg{sup -1} tetramethylammonium trifluoromethylsulfonate, (CH{sub 3}){sub 4}N(F{sub 3}CSO{sub 3}) {l_brace}TMATFMS{r_brace} in order to assess the effect of both cation complexation by EDTA{sup 4-} and anion activity coefficient variations. The resulting hydrolysis quotients are discussed with reference to applications in boiler and heat exchanger chemical cleaning, as well as chemical and nuclear waste containment. Some recent diverse uses of this emf technique that also pertain to these applications will be mentioned briefly, e.g., surface absorption - zero-point-of-charge - measurements to high temperatures and in situ pH measurements in solubility and kinetic experiments.
Date: February 1, 1995
Creator: Palmer, D. A. & Nguyen-Trung, Chinh
Partner: UNT Libraries Government Documents Department

Electrical conductivity measurements of aqueous electrolyte solutions at high temperatures and high pressures

Description: In aqueous solutions all electrolytes tend to associate at high temperatures (low dielectric constants). Ion association results in the formation of uncharged substrates, which are substantially more volatile than their precursor ions. Thus knowledge of the association constants is important in interpreting the thermodynamics of the partitioning of electrolytes to the vapor phase in a fully speciated approach. Electrical conductance measurements provide a unique window into ionic interactions of solutions at high temperatures and pressures. In this study, the electrical conductivities of dilute (<0.1 molal) aqueous solutions of NaCl (100-600{degrees}C to 300 MPa) and sodium and potassium hydroxides (0-600 and 100-600{degrees}C, respectively, and to 300 MPa) were measured. The results show that the extent of association of Na{sup +} and Cl{sup -} is similar to those for Na{sup +} and K{sup +} with OH{sup -} in solution from subcritical to supercritical conditions.
Date: February 1, 1995
Creator: Ho, P. C. & Palmer, D. A.
Partner: UNT Libraries Government Documents Department

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

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

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 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

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

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

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

Production and mitigation of acid chlorides in geothermal steam

Description: Measurements of the equilibrium distribution of relatively nonvolatile solutes between aqueous liquid and vapor phases have been made at temperatures to 350{degrees}C for HCl(aq) and chloride salts. These data are directly applicable to problems of corrosive-steam production in geothermal steam systems. Compositions of high-temperature brines which could produce steam having given concentrations of chlorides may be estimated at various boiling temperatures. Effects of mitigation methods (e.g., desuperheating) can be calculated based on liquid-vapor equilibrium constants and solute mass balances under vapor-saturation conditions.
Date: June 1, 1995
Creator: Simonson, J. M. & Palmer, D. A.
Partner: UNT Libraries Government Documents Department

Liquid-vapor partitioning of NaCl(aq) from concentrated brines at temperatures to 350{degrees}C

Description: Compositions of coexisting liquid and vapor phases have been determined at temperatures from 250 to 350{degree}C for brines containing NaCl and either HCl or NaOH by direct sampling of both phases from a static phase-equilibration apparatus. Thermodynamic partitioning constants for NaCl have been determined from the observed compositions of the coexisting phases combined with the known activity coefficients of NaCl(aq) in the liquid phase. An apparent dependence of the values of these partitioning constants on brine concentration is explained by considering the effect of decreasing pressure on the density of the vapor phase. Concentrations of HCl and NaCl in steam produced from various natural brines may be calculated as functions of temperature and brine composition based on these new results coupled with our previous determinations of the partitioning constants for HCl(aq). Application of these results to The Geysers will be discussed in terms of the composition of postulated brines which could be in equilibrium with observed steam compositions at various temperatures.
Date: March 1, 1994
Creator: Simonson, J. M.; Palmer, D. A. & Carter, R. W.
Partner: UNT Libraries Government Documents Department

Potentiometric studies at ORNL with hydrogen electrode concentration cells

Description: The absence of suitably stable reference electrodes for and to 300 C led ORNL to develop hydrogen electrode concentration cells for studies of equilibria of interest in reactor and steam generator systems to about 300 C during the late 1960`s and seventies. During the intervening two dozen years over twenty scientists have participated in potentiometric studies at Oak Ridge and much of that work will be summarized in this paper. A description of hydrogen electrode concentration cells developed in the late sixties and currently in use at Oak Ridge is given. The method of measurement, data interpretation, and published results are reviewed for studies of acid-base ionization, metal ion hydrolysis, and metal complexation reactions using principally such cells in titration or flow modes. 41 refs.
Date: December 31, 1994
Creator: Mesmer, R. E.; Palmer, D. A. & Wesolowski, D. J.
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

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

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

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

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

Partitioning of solutes between liquid water and steam in the system {l_brace}Na-NH{sub 4}-NH{sub 3}-H-Cl{r_brace} to 350{degree}C

Description: Measurements have been made of the partitioning of solutes between liquid and vapor phases for hydrochloric acid and chloride salts found in both power plant steam cycles and in natural geothermal systems. Static sampling of equilibrium liquid and vapor phases extended from 350 C to the lowest temperatures for which reliable analytical determinations of vapor-phase solute concentrations could be made. Equilibrium constants for the partitioning of the various solutes were calculated from the measured equilibrium compositions, and represented as functions of temperature and solvent density over the full temperature range investigated. These equilibrium constants can be used to calculate equilibrium compositions of coexisting liquid and vapor phases under conditions ranging from steam production from saline geothermal brines to early-condensate formation in all-volatile treatment steam cycles.
Date: December 31, 1994
Creator: Simonson, J. M. & Palmer, D. A.
Partner: UNT Libraries Government Documents Department