Measurement and modeling of mean activity coefficients of NaBr and amino acid in (sodium bromide + potassium phosphate + glycine + water) system at T (298.15 and 308.15) K

Electrochemical measurements are done on (water + NaBr + K₃PO₄ + glycine) mixtures at T (298.15 and 308.15) K by using (Na⁺ glass) and (Br⁻ solid-state) ion selective electrodes. The mean ionic activity coefficients of NaBr are determined at five NaBr molalities (0.1, 0.3, 0.5, 0.7, and 1) in the above mixtures. The activity coefficients of glycine are evaluated from mean ionic activity coefficients of sodium bromide. The ratio of mean ionic activity coefficient of NaBr in the (water + NaBr + K₃PO₄ + glycine) mixtures to the mean ionic activity coefficients of NaBr at the same molalities in the (H₂O + NaBr) mixtures are correlated by using a new expression.     

Determination of the Glass Electrode Parameters by Means of Potentiometric Titration of Acetic Acid in Aqueous Sodium or Potassium Chloride Solutions at 25°C

Single-ion activity coefficient equations are presented for the calculation of stoichiometric (molality scale) dissociation constants K _m for acetic acid in aqueous NaCl or KCl solutions at 25°C. These equations are of the Pitzer or Hückel type and apply to the case where the inert electrolyte alone determines the ionic strength of the acetic acid solution considered. K _m for a certain ionic strength can be calculated from the thermodynamic dissociation constant K _a by means of the equations for ionic activity coefficients. The data used in the estimation of the parameters for the activity coefficient equations were taken from the literature. In these data were included results of measurements on galvanic cells without a liquid junction (i.e., on cells of the Harned type). Despite the theoretical difficulties associated with the single-ion activity coefficients, K _m can be calculated for acetic acid in NaCl or KCl solutions by the Pitzer or Hückel method (the two methods give practically identical K _m values) almost within experimental error at least up to ionic strengths of about 1 mol-kg^–1. Potentiometric acetic acid titrations with base solutions (NaOH or KOH) were performed in a glass electrode cell at constant ionic strengths adjusted by NaCl or KCl. These titrations were analyzed by equation E = E _o + k(RT/F) ln[m(H⁺)], where m(H⁺) is the molality of protons, and E is the electromotive force measured. m(H⁺) was calculated for each titration point from the volume of the base solution added by using the stoichiometric dissociation constant K _m obtained by the Pitzer or Hückel method. During each base titration at a constant ionic strength, E _o and k in this equation were observed to be constants and were determined by linear regression analysis. The use of this equation in the analysis of potentiometric glass electrode data represents an improvement when compared to the common methods in use for two reasons. No activity coefficients are needed and problems associated with liquid junction potentials have been eliminated.     

Thermodynamics of mixed electrolyte solutions. IX. Calculation of the osmotic and activity coefficients in a pseudoternary system (NaCl−nKCl)−MgCl2-H2O at 298.15°K

The equation of Reilly, Wood, and Robinson was used to predict the osmotic coefficient of a pseudoternary system (NaCl–nKCl)–MgCl₂–H₂O over a molal ionic strength range of 1.0 to 5.0 moles-kg^–1. The results are in close agreement with experimental data at most ionic strengths. The standard deviation in the osmotic coefficients over the entire concentration range lies within 0.0035. The predicted values of the mean activity coefficients are in good agreement with those obtained by the treatments of both Scatchard and Friedman. Mean activity coefficients for the other components were also predicted.     

Osmotic and activity coefficients in the binary solutions of 1-butyl-3-methylimidazolium chloride and bromide in methanol or ethanol at T = 298.15 K from isopiestic measurements

Osmotic coefficients of the binary solutions of two room-temperature ionic liquids (1-butyl-3-methylimidazolium chloride and bromide) in methanol and ethanol have been measured at T = 298.15 K by the isopiestic method. The experimental osmotic coefficient data have been correlated using a forth-order polynomial in terms of (molality)^0.5, with both, ion interaction model of Pitzer and electrolyte non-random two liquid (e-NRTL) model of Chen. The values of vapor pressures of above-mentioned solutions have been calculated from the osmotic coefficients. The model parameters fitted to the experimental osmotic coefficients have been used for prediction of the mean ionic activity coefficients of those ionic liquids in methanol and ethanol.     

Specific ionic interactions in the quaternary systems HCl−NaCl−KCl-water and HCl−NH4Cl−KCl-water at 25°C

Mean ionic activity coefficients of hydrochloric acid in the systems HCl–NaCl–KCl-water and HCl–NH₄Cl–KCl-water at constant total ionic strength of 1 mole-kg^–1 have been determined for various ratios of the added salts at 25°C. The electromotive force method was used. Both an extended form of the simple empirical Harned equations (see ref. 1) and the more complicated semiempirical Pitzer equations (see refs. 2–4) for multicomponent electrolyte systems were used in the treatment of the data. Specific ionic interaction parameters for both types of equations are reported. The effects of the added salts on the thermodynamic behavior of HCl in the two systems mentioned were compared by considering the variation of its trace activity coefficient with change in amounts of the added salts at constant total ionic strength of 1 mole-kg^–1.     

Correlation of the Solubilizing Abilities of 1-Butyl-1-methylpiperidinium Bis(trifluoromethylsulfonyl)imide and 1-Butyl-1-methylpyrrolidinium Tetracyanoborate

Chromatographic retention data were measured for a wide range of organic solutes on 1-butyl-1-methylpyrrolidinium tetracyanoborate ([BMPyrr]⁺[B(CN)₄]^?) and 1-butyl-1-methyl-piperidinium bis(trifluoromethylsulfonyl)imide ([BMPip]⁺[Tf₂N]^?) stationary phases at 323 K and 353 K. The measured retention factors were combined with published infinite dilution activity coefficient and gas-to-water partition coefficient data to yield gas-to-anhydrous ionic liquid (IL) and water-to-anhydrous IL partition coefficients. Both sets of partition coefficients were analyzed using the Abraham model. The derived Abraham model correlations describe the observed gas-to-IL (log₁₀ K) and water-to-IL (log₁₀ P) partition coefficient data to within average standard deviations of about 0.10 and 0.15 log₁₀ units, respectively.     

Correlation of the Solubilizing Abilities of 1-Butyl-1-methyl-pyrrolidinium Tris(pentafluoroethyl)trifluorophosphate, 1-Butyl-1-methylpyrrolidinium Triflate and 1-Methoxyethyl-1-methylmorpholinium Tris(pentafluoroethyl)trifluorophosphate

Chromatographic retention data were measured for a wide range of organic solutes on 1-butyl-1-methylpyrolidinium tris(pentafluoroethyl)trifluorophosphate ([BMPyrr]⁺[FAP]^?), 1-butyl-1-methylpyrrolidinium triflate, ([BMPyrr]⁺[Trif]^?), and 1-methoxyethyl-1-methylmorpholinium tris(pentafluoroethyl)trifluorophosphate, ([MeoeMMorp]⁺[FAP]^?), stationary phases at (323, 353 and 383) K. The measured retention factors were combined with published infinite dilution activity coefficient and gas-to-water partition coefficient data to yield gas-to-anhydrous ionic liquid (IL) and water-to-anhydrous IL partition coefficients. The three sets of partition coefficients were analyzed using the Abraham model. The derived Abraham model correlations describe the observed gas-to-IL (log₁₀ K) and water-to-IL (log₁₀ P) partition coefficient data to within average standard deviations of about 0.11 and 0.15 log₁₀ units, respectively.     

Correlation of the extraction constant values of Cu(II) by 5-dodecylsalicylaldoxime from phosphoric acid media

The equilibrium constant values of copper(II) extraction from phosphoric acid media by LIX 622 (67.7% 5-dodecylsalicylaldoxime, Cognis Ireland) taking into account the formation in the organic phase of the complex CuL₂, HL being 5-dodecylsalicylaldoxime, at different ionic strengths have been calculated. Elmore's model has been considered for the speciation of the aqueous phase. A new approach for the calculation of the activity coefficient of H₂PO₄⁻ has also been proposed. The extraction equilibrium constant values obtained at the different ionic strengths have been successfully correlated considering the activity coefficients of the species in solution as well as the release of water molecules in the extraction process. The extraction constant value at infinite dilution of the complex CuL₂ is also reported.     

Osmotic and activity coefficients in the binary solutions of 1-butyl-3-methylimidazolium chloride and bromide in methanol or ethanol at T = 298.15 K from isopiestic measurements

Osmotic coefficients of the binary solutions of two room-temperature ionic liquids (1-butyl-3-methylimidazolium chloride and bromide) in methanol and ethanol have been measured at T = 298.15 K by the isopiestic method. The experimental osmotic coefficient data have been correlated using a forth-order polynomial in terms of (molality)^0.5, with both, ion interaction model of Pitzer and electrolyte non-random two liquid (e-NRTL) model of Chen. The values of vapor pressures of above-mentioned solutions have been calculated from the osmotic coefficients. The model parameters fitted to the experimental osmotic coefficients have been used for prediction of the mean ionic activity coefficients of those ionic liquids in methanol and ethanol.     

Ionogels: Squeeze flow rheology and ionic conductivity of quasi-solidified nanostructured hybrid materials containing ionic liquids immobilized on halloysite

Ionogels are hybrid ion-conducting materials consisting of ionic liquids stabilized by inorganic or polymer fillers and having good prospects for application in solid-state and flexible electronics and energy storage devices. The work presents the results of studying the rheological properties and ionic conductivity of a series of ionogels based on halloysite nanoclay and bis(trifluoromethylsulfonyl)imide ionic liquids with EMIm⁺, BMIm⁺, BM₂Im⁺, BMPyrr⁺, BMPip⁺ and MOc₃Am⁺ cations and content of the dispersion phase of 43–48%. The obtained values are compared with the analogous characteristics of bulk ionic liquids. It has been established that the IL cation structural characteristics affect the viscoplastic properties of ionogels subjected to uniaxial quasistatic compression (20 °C), ionic conductivity and structural resistance coefficient of an inorganic filler (from ?20 to +80 °C). Additive models of conductivity in binary systems are applied to obtain correlations linking ionic conductivity of ionogels with that of pure ionic liquids.     

Determination of the solubilising character of 2-methoxyethyl-(dimethyl)ethylammonium tris(pentafluoroethyl)trifluorophosphate based on the Abraham solvation parameter model

Gas–liquid chromatographic retention factors have been measured for 42 different organic probes on a 2-methoxyethyl(dimethyl)ethylammonium tris(pentafluoroethyl)trifluorophosphate, ([MeoeM₂EAm]⁺[FAP]^–), stationary phase capillary column at 323 and 353 K. The measured retention factors were combined with published gas-to-liquid partition coefficient data for solutes dissolved in ([MeoeM₂EAm]⁺[FAP]^–) and with published gas-to-water partition coefficient data to yield 107 gas-to-anhydrous ionic liquid and 105 water-to-anhydrous ionic liquid partition coefficients. Abraham model correlations for describing solute transfer into ([MeoeM₂EAm]⁺[FAP]^–) were derived from the three sets of experimental partition coefficient data. The derived correlations back-calculated the experimental gas-to-([MeoeM₂EAm]⁺[FAP]^–) and water-to-([MeoeM₂EAm]⁺[FAP]^–) partition coefficient data to within 0.13 and 0.15 log units, respectively.     

Mean Ionic Activity Coefficients of Alkali Metals Dissolved in High Dielectric Constant Solvents: A Comparison Between Experimental Data and Fuoss Theoretical Data

Abstract

Ionic association of strong univalent symmetrical electrolytes dissolved in Hydrogen Bonded Solvents (HBS) having high dielectric constants, has been studied in terms of mean ionic activity coefficient. This parameter has been analysed with the Fuoss's Paired Ion Model in the concentration range 0.5-500m0lm^-3. The experimental data are consistent with this model. It has been shown that fits to the experimental data could be obtained with fixed values of fraction of contact pain α and Gurney radius corresponding to the Contact Pair (CP). The results of fractions of free ions γ and conducting ions (p) as a function of concentration are also discussed. Conductimetric pairing constants K Lanbad; and Gibbs free energy δG are deduced to explain this ionic association. The iduence of the dielectric constant of the solvent on the ionic association has been also investigated in this work.     

Correlations for describing gas-to-ionic liquid partitioning at 323 K based on ion-specific equation coefficient and group contribution versions of the Abraham model

Chromatographic retention measurements were measured for a wide range of solutes on 1-methyl-3-ethylimidazolium tris(pentafluoroethyl)trifluorophosphate, ([MEIm]⁺[FAP]⁻), and 1-(3-hydroxypropyl)pyridinium tris(pentafluoroethyl)trifluorophosphate, ([1-PrOHPy]⁺[FAP]⁻), stationary phases at 323 K. The measured retention factors were combined with published infinite dilution activity coefficient, gas solubility data and retention factor data to yield gas-to-anhydrous ionic liquid (IL) partition coefficients at 323 K for 2349 different solute-IL combinations. The compiled partition coefficient data were analyzed using the ion-specific equation coefficient and the functional group contribution versions of the Abraham solvation parameter model. Ion-specific equation coefficients were calculated for 25 cations and 14 anions. In addition, values were calculated for 14 cation functional groups and 14 anions. The calculated ion-specific equation coefficients and calculated functional group values described the experimental 323 K partition coefficient data to within standard deviations of 0.10 and 0.13 log units, respectively.     

Ionic interactions in solution: VI. The activity expansion and the association concept

The activity expansion equation which expresses the solute concentration as a series expansion of the activities of the solute species is used to reach a reformulation of the mean activity coefficient of a binary symmetrical electrolyte in solution. The result is displayed as the product of a shortrange term and a long-range term f_±=f _± ^S ·f^L _±, from which a straightforward derivation of the Bjerrum treatment is obtained. The analogy with an equivalent formulation for the molar conductance coefficient which results from the application of the echo-effect is emphasized. A simple formulation of the ion pair distribution function is proposed which is particularly powerful for ionic systems involving strong interactions. It is shown that the variable which controls the excess transport and thermodynamic quantities is not so much the stoichiometric concentration but rather the product of the concentration with the short-range factor f _± ^S of the activity coefficient product derived in the present work. In dilute solutions this factor becomes the so-called fraction of free ions originally introduced somewhat empirically by Bjerrum by means of a chemical model.Dedicated to Johannes Coetzee on the occasion of his 65th Birthday.     

Correlation of the Solubilizing Abilities of Hexyl(trimethyl)ammonium <Emphasis Type="Italic">bis</Emphasis>((Trifluoromethyl)sulfonyl)imide, 1-Propyl-1-methylpiperidinium <Emphasis Type="Italic">bis</Emphasis>((Trifluoromethyl)sulfonyl)imide,and 1-Butyl-1-methyl-pyrrolidinium Thiocyanate

Chromatographic retention data were measured for a wide range of organic solutes on 1-butyl-1-methylpyrrolidinium thiocyanate ([BMPyrr]⁺[SCN]⁻), hexyl(trimethyl)ammonium bis((trifluoromethyl)sulfonyl)imide ([HexM₃Am]⁺[(Tf)₂N]⁻), and 1-propyl-1-methylpiperidinium bis((trifluoromethyl)sulfonyl)imide ([PMPip]⁺[(Tf)₂N]⁻) stationary phases at 323 and 353 K. The measured retention factors were combined with published infinite dilution activity coefficient and gas-to-water partition coefficient data to yield gas-to-anhydrous ionic liquid (IL) partition coefficients and water-to-anhydrous IL partition coefficients. Both sets of partition coefficients were analyzed using the Abraham model. The derived Abraham model correlations describe the observed gas-to-IL and water-to-IL partition coefficient data to within average standard deviations of 0.116 and 0.156 log₁₀ units, respectively.     

Molecular dynamics simulation of ionic transport on molten Li–KCl interface

A molecular dynamics study is performed to determine the dynamics and transport properties of the ions on the molten interface between anode metal Li and electrolyte KCl. Radial distribution function of the ionic pair and the behavior of the mean‐square displacement (MSD) as a function of time (t) indicate that KCl and metal Li are in the molten state at 2,200 K in the canonical ensemble. The dynamics of the ionic transport are characterized by studying MSD for the centers of mass of the ions at different temperatures. Diffusion coefficient is evaluated from the linear slope of the MSD (t) function in the range of 0–500 ps. The MSD and diffusion coefficient of the Li⁺ ions are much larger than those of the Cl^? and K⁺ ions due to the difference in ionic characteristic. The transport process has been dominated by the Li⁺ ions on the molten interface and the Li⁺ ions are main charge carriers. The energy barrier of the Li⁺ ions transporting into the molten KCl is fitted to be 5.28 kcal/mol in the light of the activation model. The electrical conductivity of the Li⁺ ions transporting into the molten KCl are calculated from the Nernst–Einstein formula to be in the range of 0.2–0.3 S cm^?1. The current density resulted from the Li⁺ ions through the interface are estimated to be an order of 10⁶ A cm^?2, which may be the value corresponding to a larger concentration gradient of the Li⁺ ions. Simulated results at different temperatures show that the diffusion coefficient, conductivity and current density have increased with the temperature. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Thermodynamics of multicomponent electrolyte solutions: Aqueous mixtures of two salts from among NaCl,KCl, NaH2PO4, and KH2PO4 at 25° C

Five of the six possible aqueous two-salt mixtures from among NaCl, KCl, NaH₂PO₄,and KH₂PO₄ have been studied by the isopiestic method at 25°C. The sixth mixture, NaCl–KCl, has been studied previously. The deviations from ideal mixing behavior are described by a series of coefficients which were found by regression analysis. The coefficients were used to calculate the excess Gibbs energies of mixing for equal ionic strength fractions of each salt and the trace activity coefficient of each salt at an ionic strength of 2 mode-kg^–1. The cross-square mixing rule is obeyed within experimental uncertainty for the excess Gibbs energies of mixing.     

Proton Conductor of Propylene Carbonate–Plasticized Carboxyl Methylcellulose–Based Solid Polymer Electrolyte

Carboxyl methylcellulose (CMC) solid polymer electrolytes were prepared by utilizing oleic acid (OA) and different wt.% of propylene carbonate (PC) by using the solution casting technique. An ionic conductivity study of the films was done by using impedance spectroscopy. The highest ionic conductivity gained is 2.52 × 10^?7 S cm^?1 at ambient temperature for sample CMC-OA-PC 10 wt.%. From transference number measurement (TNM), the value of cation diffusion coefficient, D₊, and ionic mobility, μ₊, was higher than the value of anion diffusion coefficient, D_?, and ionic mobility, μ_?. Thus, the results prove that the present samples were proton conductors.     

Comparative Investigation of the Ionicity of Aprotic and Protic Ionic Liquids in Molecular Solvents by using Conductometry and NMR Spectroscopy

Electrical conductivity (σ), viscosity (η), and self‐diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium‐based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15 K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate, [bmIm][BF₄], displays 100 % ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the ¹H NMR chemical shifts of the ionic liquids. The self‐diffusion coefficients D of the cation and anion of [HmIm][CH₃COO] in D₂O and in [D₆]DMSO are determined by using ¹H nuclei with pulsed field gradient spin‐echo NMR spectroscopy.     

The spectrophotometric determination of gold with bromopyrogallol red

Optimum conditions were found for the reaction of Au(III) with bromopyrogallol red and a new spectrophotometric determination of Au(III) ions was developed. At a wavelength of 400 nm the Lambert-Beer law is followed in a range of 0.1 to 3.0 μg Au ml^?1 and the absorption coefficient ? = 3 × 10⁴M^?1 cm^?1. The effect of cationic tensides on the studied reaction was also studied; it was found that in their presence the properties of the system are strongly affected by the ionic strength of the solution. The changes observed are a result of the effect of the ionic strength on the dissociation constant of the DG-tenside system.