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Effect of hydrotropic salts on phase relationships involving hydrocarbons, water, and alcohols

Description: Hydrotropic salts, which can increase the solubility of organic materials in aqueous solutions, are useful to tertiary oil recovery. We have examined effects on solubility of hydrocarbons in water (with and without alcohols) through addition of inorganic hydrotropic salts, such as perchlorates, thiocyanates, and iodides - high in the usual Hofmeister series - and of organic salts such as short chain alkyl benzene sulfonates and other salts based on substituted benzene derivatives. Although the inorganic salts are relatively ineffective in increasing solubility of hydrocarbons in water, many of the organic salts are excellent hydrotropic agents for hydrocarbons. We have examined the phase relationships for several series of aromatic salts such as sulfonates, carboxylates and hydroxycarboxylates, as a function of alkyl-carbon substitution in three-component (hydrocarbon, salt, water) and in four-component (hydrocarbon, salt, alcohol, water) systems. We have also examined miscibility relationships for a given hydrotropic salt as the chain length of alkanes and alkyl benzenes is systematically varied. While miscibilities decrease with increase in chain length of the hydrocarbon, the hydrotropic properties in these systems increase rapidly with the number of alkyl carbons on the benzene ring of the salts and they are relatively insensitive to the type of charged group (sulfonate vs carboxylate) attached to the benzene ring. However, there were significant increases in hydrotropy as one goes from equally substituted sulfonates or carboxylates to salicylates. A number of salts have been identified which have much greater hydrotropic properties for hydrocarbons than such well-known hydrotropic materials as toluene and xylene sulfonates.
Date: January 1, 1980
Creator: Ho, P.C. & Kraus, K.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

Amphiphilic compounds in enhanced oil recovery. Biennial report, October 1, 1980-September 30, 1982

Description: Research results covering the final two years of this program are reported in four categories: phase studies; free energies; small-angle neutron scattering; and adsorption of inorganic ions on hydrous oxides. In the early years, distributions of cations between minerals and solutions covering the salinity range of formation waters were measured. Clays and hydrous oxides were emphasized because of their high ion-exchange capacity. The objectives were to determine the equilibria between sodium and hardness ions (particularly Ca(II)) because of their importance in modeling the solids as a source of troublesome multivalent ions. A further purpose on a collateral program was to evaluate the conditions under which the adsorption of potential tracers is low enough so that retardation of their movement relative to ground water is not great enough to impair their usefulness. From the beginning to the present, the properties of aqueous-hydrocarbon systems containing amphiphiles have been the major interest. The particular area we have emphasized is comparison of behavior when the organic-electrolyte amphiphile (protosurfactant) is of an equivalent weight lower than that necessary for formation of large micelles with that when it is in the surfactant range. In general, we have found surprisingly little qualitative difference between the two classes. Protosurfactants solubilize substantial amounts of hydrocarbons in aqueous medias, and cause the same types of phase behavior in compositions modeling micellar floods as surfactants. More recently, an increasing fraction of our effort has been in applying small-angle neutron scattering (SANS) to micellar systems and in further development of the techniques for doing so.
Date: September 1, 1984
Creator: Ho, P.C. & Johnson, J.S. Jr. (comps.)
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

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

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

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