Infinite Dilution Partial Molar Volumes Research Articles

Vitamin C-amino acid interactions in aqueous solutions: Volumetric and interfacial properties

Nature of interactions occurring in aqueous solutions have been studied to understand various phenomena such as protein stabilization, drug-delivery, and food preservation. These interactions have been studied by measuring physicochemical properties of mixed aqueous solutions. Herein, we have measured the volumetric and interfacial properties of vitamin C (VC) in aqueous solutions of amino acids (Glycine, Gly; L-Leucine, Leu). Volumetric were studied at temperatures (298.15 K to 313.15 K). Transfer volumes were obtained from infinite dilution partial molar volumes of VC in aqueous Gly-and Leu-solutions. Positive transfer volumes (∆tV2° and ∆tK2) were observed, which decreases as Gly > Leu, suggesting dominance of hydrophilic-ionic interactions. Double derivative, (∂2V2° /∂T2)P suggest chaotropic nature of VC in presence of amino acids. Nature of interactions influencing interfacial properties (contact angle and surface tension) has also been evaluated at 298.15 K. Solute-co-solute interactions not much influence the interfacial properties.

Density, speed of sound, and surface tension of binary aqueous solutions containing ammonium based protic ionic liquids

Density, ρ, speed of sound, u, and surface tension γ, of binary mixtures containing ethanolammonium based protic ionic liquids (PILs) and water were measured to access the influence of PIL-water interactions on physicochemical properties. Volumetric properties of PILs were evaluated at ambient pressure but at temperatures from 298.15 K to 313.15 K. Apparent molar volume and apparent molar isentropic compressibility values of ethanolammonium acetate [EAAc], ethanolammonium butanoate [EABu], and ethanolammonium hexanoate [EAHx], were calculated and commuted to determine the infinite dilution partial molar volume using Redlich-Mayer type of equation. Further, excess molar volume was also determined as a function of mole fraction. The coefficients of Redlich-Kister equation also determined and presented. Overall, the hydrophilic interactions occur between PILs and water molecules and the strength of interactions weakens as anionic chain length increases. Low surface tension values were observed for PILs with longest alkyl chain. The results indicate that hydrophobicity of alkyl chain strongly influences the interfacial properties.

The retention factors and partial molar volumes of ibuprofen at infinite dilution in supercritical carbon dioxide at T= (308.15, 313.15, 323.15, 333.15, 343.15 and 353.15) K

Here is presented the first experimental data for the infinite dilution partial molar volumes of ibuprofen in supercritical carbon dioxide. The measurements were carried out by supercritical fluid chromatography using chemically bonded polyethylene glycol and carbon dioxide as stationary and mobile phases, respectively. The chromatographic retentions of ibuprofen at infinite dilution in supercritical carbon dioxide were measured at six supercritical isotherms of 308.15, 313.15, 323.15, 333.15, 343.15 and 353.15 K and at a pressure range of 8.50–40.00 MPa. The partial molar volumes were determined from the partial derivatives of the retention factors with respect to the densities and were in the range of −2.364 × 10−3 to 1.680 × 10−4 m3/mol. A reverse behaviour was observed, where the partial molar volumes decreased monotonically with decreasing pressure from positive to negative values in all temperature regions investigated. It was also found that the infinite dilution partial molar volumes showed a sharp decrease near the critical point of carbon dioxide. The experimental partial molar volumes were correlated with isothermal compressibilities and densities of carbon dioxide. The correlation proposed in this study could predict the experimental data with an average absolute relative deviation of 4.6% for 80 data points, which is better than that previously reported in the literature.

Aqueous solutions of [EMIM] 1,1,2,2-tetrafluoroethanesulfonate and [EMIM] trifluoromethanesulfonate: A thermodynamic study

Abstract While ionic liquids (ILs) based on a trifluoromethanesulfonate ([OTF] − ) anion and their mixtures with other compounds have been relatively well explored, the information about structurally similar 1,1,2,2-tetrafluoroethanesulfonate-based ([TFES] − ) ILs is either very scarce or, as in the case of their mixtures with water, totally lacking. We herein thus present a broad thermodynamic characterization of aqueous solutions of [EMIM][TFES] and [EMIM][OTF], with the study of aqueous solutions of the latter serving as a benchmark. First, the peculiar solid-liquid phase transition behavior of the neat [EMIM][TFES] was examined and its density was determined over a temperature range encompassing both the subcooled and the stable liquid. For the aqueous solutions of the two ILs, we performed extensive measurements at several temperatures in the range from (288.15 to 318.15) K of water activity ( a w ) across the entire composition range, mixing enthalpy and density specifically in the highly dilute IL region, and the solution freezing temperatures at water mole fractions greater than 0.6. The ample a w data were fitted ( i ) by a two-step procedure and ( ii ) simultaneously with the excess enthalpy data using an extended NRTL-type model. Although both treatments provide adequate representations of the data and prove to yield reasonable estimates of derivative thermal properties, the latter approach to the global description of energetics of the systems is preferred for its handiness in practical calculations. We duly proved its reliability in extrapolation and/or prediction against experimental data on various properties, among others, SLE. The analysis of volumetric data by the Redlich-Meyer equation allowed us to obtain accurate values of infinite dilution partial molar volumes of the ILs and revealed the nature of their hydration as rather hydrophobic. The solution behavior of the systems studied was found to be essentially non-ideal: their small S-shaped excess Gibbs energy ( G E ) actually results from the compensation of their large positive excess enthalpy ( H E ) and entropy ( S E ). Thus, despite being completely miscible with water, the two ILs are not typically hydrophilic, but intermediate on an imaginary (hydrophobicity/hydrophilicity) scale. The structural variation in the anion, though influencing H E and S E considerably, is only subtly reflected in G E and activity coefficients. Due to their somewhat lower values and a weaker decrease of apparent molar volume with increasing molality observed for [EMIM][TFES], [TFES] − is identified to be slightly more hydrophilic than [OTF] − .

COMPORTAMIENTO VOLUMÉTRICO DE LA DL-VALINA EN SOLUCIONES ACUOSAS DE NITRATO DE SODIO A DIFERENTES TEMPERATURAS

Densities of DL-valine (2-amino-3-methylbutanoic acid) in aqueous solutions of sodium nitrate were determined at temperatures ranging from 283.15 to 318.15 K using an Anton Paar DMA 5000 vibrating tube densitometer. The apparent molar volume, infinite dilution apparent molar volume, second derivative of the infinite dilution partial molar volume with respect to temperature, partial molar volume of transfer at infinite dilution and the number of hydration were calculated. The results obtained were discussed in terms of the dominant interactions in solution, it was found that the DL-valine has a disruptor effect in the structure of the solvent and that at infinite dilution solute-solvent interactions are dominant between isopropyl group the amino acid and sodium and nitrate ions.

Thermodynamic properties of five biofuel-relevant compounds at infinite dilution in water

In this work, thermodynamic behavior of five biomass-derived compounds, namely furfural, 2-methylfuran, 2,5-dimethylfuran, methyl vinyl ketone, and allyl alcohol, in highly dilute aqueous solutions has been experimentally investigated. Using the inert gas stripping technique, their air-water partition coefficients (Kaw) and limiting activity coefficients γ1∞ were measured at several temperatures in the range from (273 to 333) K. Except for the furans, infinite dilution partial molar excess enthalpies and volumes were further determined as functions of temperature from (288 to 318) K by tandem flow mixing calorimetry and vibrating-tube densimetry, which in turn allowed reliable derivation of respective heat capacities and expansivities. In addition, densities of all five pure liquids and viscosities of furfural and allyl alcohol were also measured in the range from (288 to 318) K. For each compound, the vapor-liquid equilibrium and (when measured) calorimetric data of this work together with some relevant data reported previously in the literature were simultaneously correlated by a three-parameter model equation providing adequate simultaneous description of all information involved. As a result, recommended thermodynamically consistent temperature dependences of Kaw and γ1∞ of superior accuracy were thus established in the range from the melting point to the normal boiling point of water. The variation of Kaw and γ1∞ with temperature and solute molecular structure along with related energetic functions of dissolution and hydration of the examined compounds were overviewed and briefly discussed.

Modulation of volumetric properties of d(+)-glucose in aqueous 3-hydroxypropylammonium acetate solutions

Study of hydration behavior of solute is required to understand the role of water in taste mechanisms, and the effect of additive on basic taste quality of solute. In this regard, apparent molar volume, apparent specific volume, apparent molar isentropic compressibility and apparent specific isentropic compressibility of Glu in aqueous solutions of 3-hydroxypropylammonium acetate (3HPAAc) have been determined at 293.15K to 318.15 and at atmospheric pressure from experimentally measured density, ρ and speed of sound, u data. Derived parameters such as infinite dilution partial molar volumes, V2°, partial molar isentropic compressibilities, volume of transfer, expansion coefficients, hydration numbers, and interaction coefficients were also determined to discuss various interactions occurring between solute and cosolute in aqueous solutions. The effect of cationic and anionic moiety of 3HPAAc on the basic taste behavior of Glu has also been studied on the basis of apparent specific volume and apparent specific isentropic compressibility.

Solvation free energy and solubility of acetaminophen and ibuprofen in supercritical carbon dioxide: Impact of the solvent model

Classical molecular dynamics simulations are used to compute the solvation free energy of two pharmaceutical solids, namely ibuprofen and acetaminophen in carbon dioxide (CO2), over the density range of interest in supercritical processes. In order to examine the influence of the solvent model on the resulting free energies, three popular CO2 models (Zhang, EPM2, and TraPPE) are studied. Relatively large discrepancies for the solvation free energy exist between these CO2 models, suggesting that the former is sensitive to the different balances between dispersive and electrostatic forces used in these models. In particular, for the solvation of the highly polar (dipole moment of ∼5.2Debye) acetaminophen molecule, such discrepancies are more pronounced than for the moderately polar ibuprofen (dipole moment of ∼1.6D) molecule. Since there is an exponential relationship between the solvation free energy and solubility, the choice of the solvent model substantially affects the predicted solubility. For the solubility of the studied solutes, the value obtained using the TraPPE model is the highest, that of the EPM2 model is intermediate, and that of the Zhang model is the lowest. Generally, the simulations results show that the model with the largest quadrupole moment leads to a more negative solvation free energy and a higher solubility over the entire density range. Further, the decomposition of the solvation free energy into contributions stemming from electrostatics and dispersion interactions shows that the electrostatic interactions are important for a quantitative prediction of solid solubility, while the Lennard–Jones parameters of the solute and solvent are more important for qualitative agreement. Additionally, the infinite-dilution partial molar volume of the two solutes is estimated from the pressure derivative of the solvation free energies. With density increasing beyond the value corresponding to the zero partial molar volume of the solute (minimum solvation free energy), the repulsive part of Lennard–Jones potential wins over the attractive interactions, and the solvent strength of supercritical CO2 decreases; however, due to the increase in the chemical potential of the pure solid (effect of the Poynting correction), the solubility further increases. Overall, these results demonstrate the importance of a proper choice of quadrupole moment of the solvent model, which is crucial for quantitative predictions of the solid solubility in supercritical CO2.

Partial molar volumes and viscous properties of glycine-aqueous urea solutions at 298.15 K

Density (ρ) and viscosity (η) of glycine (c = 0.02–0.22 mol dm−3) in aqueous urea (c = 0.5, 1.5, and 3.0 mol dm−3) solutions were measured at 298.15 K. Experimental density data has been used to calculate apparent molar volumes (φv) of glycine in aqueous and aqueous-urea solutions at 298.15 K. The dependence of apparent molar volumes on concentration of glycine was fitted to the Massons relation and apparent molar volume of glycine at infinite dilution (partial molar volume, φv0) was determined graphically. The partial molar volumes of transfer (Δtrφv0) of glycine at infinite dilution from pure water to aqueous-urea solutions at 298.15 K were calculated and interpreted in terms of various interactions and structural fittings in studied solutions. The relative viscosity data has been analyzed by Jones-Dole relation and viscosity B-coefficients were determined graphically. Viscosity B-coefficient of transfer (ΔB) was also calculated and compared with Δtrφv0.

Volumetric properties of 1-butyl-3-methylimidazolium bromide in aqueous solutions of d(−)-ribose and d(−)-arabinose at different temperatures

In this work, we report the densities, ρ and apparent molar volumes of imidazolium based ionic liquid (1-butyl-3-methylimidazolium bromide, [Bmim]Br) in water and in aqueous solutions of two pentoses namely d(−)-ribose (Rib) and d(−)-arabinose (Arb) at different temperatures (288.15 to 318.15) K and at atmospheric pressure. The infinite dilution partial molar volume, V2° and empirical parameters (Sv and Bv) were evaluated by using Redlich-Mayer type of equation. The volume of transfer (ΔtV2°) for [Bmim]Br from water to aqueous monosaccharide solutions were found to be positive and decrease in the following order: Rib>Arb. The Sv, Bv ΔtV2° and other parameters such as expansion coefficients and interaction coefficients were discussed in terms of interactions occurring between monosaccharides and ionic liquid. Modulation of volumetric properties of BmimBr in mixed aqueous solutions has also been discussed in relation to the stereochemistry of monosaccharides.

Thermodynamic and ultrasonic properties of ascorbic Acid in aqueous protic ionic liquid solutions.

In this work, we report the thermodynamic and ultrasonic properties of ascorbic acid (vitamin C) in water and in presence of newly synthesized ammonium based protic ionic liquid (diethylethanolammonium propionate) as a function of concentration and temperature. Apparent molar volume and apparent molar isentropic compression, which characterize the solvation state of ascorbic acid (AA) in presence of protic ionic liquid (PIL) has been determined from precise density and speed of sound measurements at temperatures (293.15 to 328.15) K with 5 K interval. The strength of molecular interactions prevailing in ternary solutions has been discussed on the basis of infinite dilution partial molar volume and partial molar isentropic compression, corresponding volume of transfer and interaction coefficients. Result has been discussed in terms of solute-solute and solute-solvent interactions occurring between ascorbic acid and PIL in ternary solutions (AA + water + PIL).

Volumetric and ultrasonic properties of ternary (sucrose + water + protic ionic liquid) solutions

In this work, apparent molar volume and apparent molar isentropic compressibility of sucrose in aqueous solutions of ammonium based protic ionic liquid (PIL) have been evaluated from experimentally determined values of density and speed of sound at T=(293.15, 298.15, 303.15, 308.15, 313.15 and 318.15)K and at 101.3kPa. The types of interactions occurring between sucrose and PIL (3-hydroxypropylammonium formate; 3HPAF) in aqueous solutions were studied and are discussed on the basis of infinite dilution partial molar volumes, V2°, and isentropic compressibility, Ks,2°, transfer volume and compressibility (ΔtV2° and ΔtKs,2°), expansion coefficients, [(∂V2°/∂T)P and (∂2V2°/∂T2)P], interaction coefficients, (YAB and YABB) and hydration numbers, Nw. Further, apparent specific volume, ASV and apparent specific isentropic compression, ASIC were determined and analysed to evaluate the effect of PIL on the basic taste quality of sucrose.

Volumetric Properties of Disaccharides in Aqueous Solutions of Benzyldimethylammonium Acetate as a Function of Temperature

Densities, ρ, and speeds of sound, u, of two disaccharides (D-(+)-maltose and D-(+)-cellobiose) in water and in the presence of protic ionic liquid (PIL) (i.e., benzyldimethylammonium acetate, BDMAAc) were measured at different temperatures (288.15–318.15) K at atmospheric pressure. These data were used to calculate the apparent molar volume, apparent molar isentropic compressibility, infinite dilution partial molar volume, infinite dilution partial molar isentropic compressibility, and corresponding transfer parameters (ΔtV°2 and ΔtK°s,2) for disaccharides from water to aqueous PIL solutions. The effect of BDMAAc on the basic taste quality of disaccharides was evaluated from apparent specific volume and apparent specific isentropic compressibility, as these parameters are grouped in various taste qualities.

Effect of protic ionic liquid on the volumetric properties of ribose in aqueous solutions

The densities, ρ and speeds of sound, u of d(−)-ribose in aqueous solutions of ammonium based protic ionic liquid i.e., 3-hydroxypropylammonium acetate (3HPAAc) have been measured at temperatures (298.15–318.15)K and at atmospheric pressure. These experimental data were used to calculate apparent molar volumes, V2,φ, apparent molar isentropic compressibilities, Ks,2,φ, infinite dilution partial molar volumes, V2°, and partial molar isentropic compressibilities, K°s,2 and the corresponding volumes of transfer (ΔtV2° and ΔtK°s,2). Both ΔtV2° and ΔtK°s,2 values were found to be positive, which increase with cosolute (3HPAAc) concentration and temperature, which indicate the presence of hydrophilic-ionic types of interactions between d(−)-ribose (Rib) and ions of 3HPAAc. Various derived parameters such as expansion coefficients, hydration numbers, pair and triplet interaction coefficients for Rib in aqueous 3HPAAc solutions have also been evaluated and discussed.

Effect of DBU (1,8-Diazobicyclo[5.4.0]undec-7-ene) Based Protic Ionic Liquid on the Volumetric and Ultrasonic Properties of Ascorbic Acid in Aqueous Solution

In order to understand the strength and type of interactions involved in ternary solutions, the effect of solute or cosolute concentration and temperature is needed, as an understanding of these interactions is helpful in biochemical and biophysical chemistry. In this regard, we have studied the volumetric and ultrasonic properties of one of the most important vitamins, i.e., ascorbic acid, in water and in the presence of newly synthesized protic ionic liquid (1,8-diazabicyclo[5.4.0]undec-7-en-8-ium trifluoroacetate) at temperatures of 293.15–328.15 K and at atmospheric pressure. The experimentally measured density and speed of sound data were used to calculate apparent molar volume and isentropic compressibility, infinite dilution partial molar volume, and partial molar isentropic compressibility. Volume of transfer (ΔtV2° and ΔtK°s,2), expansion coefficients, pair and triplet volumetric interaction coefficients were also evaluated and discussed in terms of various interactions occurring between ascorbic...

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15–343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide.

Thermodynamic Models for Hydrogen-Containing Systems at Infinite Dilution

For a supercritical gas such as hydrogen, thermodynamic models for Henry's constant, partial molar volume, and partial molar enthalpy are sufficient in representing the thermodynamics of hydrogen-containing systems at infinite dilution. This work presents a generalized method and correlations for Henry's constant in binary systems containing hydrogen as a function of temperature. Experimental vapor–liquid equilibrium data were used to obtain this Henry's constant correlation with (i) three specific parameters, (ii) one specific parameter, and (iii) no specific parameter. These three Henry's constant correlations for hydrogen vary in the degrees of generalization and accuracy. A generalized corresponding states correlation for partial molar enthalpy of hydrogen in hydrocarbon systems at infinite dilution was derived from the newly developed Henry's constant correlation and from a correlation for infinite-dilution partial molar volumes of hydrogen available in the literature. Overall, this work provides the most extensive method for infinite-dilution thermodynamic properties of hydrogen-containing systems.

Theory-based constraints on variations of infinite dilution partial molar volumes of aqueous solutes at various temperatures and water densities

Known theoretical relations provide constraints on variations of the partial molar volume of an infinitely diluted solute at: (1) low solvent densities (as follows from the truncated virial EoS), (2) at the critical point of the solvent (as follows from the near-critical theory of dilute mixtures); and (3) at conditions where repulsive interactions dominate, i.e. at ρc1>1.5 close to and above the Boyle temperature of a solvent, and ρc1>3 close to the melting temperature of a solvent (as follows from the theory of mixtures of hard spheres). These constraints are discussed for the case of aqueous solutions at various temperatures and water densities. The constraints provide rigorous checks of the quality of models proposed to correlate or predict V2∞ values, and, if applied properly, can significantly improve the reliability of predictions of both V2∞ and the fugacity coefficients ϕ2∞.

Interactions of glycine in aqueous solutions of 1-butyl-3-methylimidazolium tetrafluoroborate at different temperatures

INTERACTIONS OF GLYCINE IN AQUEOUS SOLUTIONS OF 1-BUTYL-3-METHYLIMIDAZOLIUM TETRAFLUOROBORATE AT DIFFERENT TEMPERATURES. Densities of glycine in aqueous solutions of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate were determined at temperatures ranging from 283.15 to 313.15 K. The apparent molar volume, infinite dilution apparent molar volume, second derivative of the infinite dilution partial molar volume with respect to temperature, partial molar volume of transfer at infinite dilution, and the number of hydration were determined. It was found that the apparent molar volume at infinite dilution was positive, but decreased with increasing ionic liquid concentration and increased with increasing temperature. On the other hand, the partial molar volume of transfer at infinite dilution behaved in a similar manner, but was negative. Keywords: volumetric properties; interactions in solution; glycine in aqueous ionic liquid.

Volumetric Properties of Binary Mixtures of 3-(Methylamino)propylamine with Water, N-Methyldiethanolamine, N,N-Dimethylethanolamine, and N,N-Diethylethanolamine from (283.15 to 363.15) K

Experimental density data of the binary mixtures of 3-(methylamino)propylamine with water, N-methyldiethanolamine, N,N-dimethylethanolamine and N,N-diethylethanolamine were reported at atmospheric pressure over the entire composition range at temperatures from (283.15 to 363.15) K. The densities were measured using an Anton Paar digital vibrating U-tube densimeter. Excess molar volumes of the mixture were calculated from the experimental densities and correlated as the Redlich–Kister equation. The optimized sets of parameters of the equation were obtained by the least-squares method at each temperature. Infinite dilution partial molar volumes and the corresponding excess partial molar volumes at infinite dilution were calculated and discussed. Thermal expansivities for the binary mixtures were presented.