Interactions of glycine,L-alanine and L-valine with aqueous solutions of trisodium citrate at different temperatures: A volumetric and acoustic approach

Densities, ρ, and speed of sound, u for glycine, L-alanine and L-valine in (0.2, 0.4, 0.6, and 0.8) mol · kg⁻¹ aqueous solutions of trisodium citrate at T = (288.15, 298.15, 308.15 and 318.15) K have been measured. The different parameters such as apparent molar volume, limiting apparent molar volume, transfer volume, have been derived from density data. Experimental values of the speed of sound were used to estimate apparent molar apparent molar isentropic compression, limiting apparent molar isentropic compression, and transfer parameter. The pair and triplet interaction coefficient have been calculated from transfer parameters.     

Effect of tri-potassium phosphate on volumetric,acoustic, and transport behaviour of aqueous solutions of 1-ethyl-3-methylimidazolium bromide at T = (298.15 to 318.15) K

Density, sound velocity, and viscosity of 1-ethyl-3-methylimidazolium bromide, [Emim][Br], in aqueous solutions of tri-potassium phosphate with salt weight fractions (w_s = 0.00, 0.10, 0.15, and 0.20) have been measured as a function of concentration of [Emim][Br] at atmospheric pressure and T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. The apparent molar volume, isentropic compressibility, apparent isentropic compressibility, and relative viscosity values have been evaluated from the experimental data. The partial molar volume and isentropic compressibility at infinite dilution, and viscosity B-coefficient obtained from these data have been used to calculate the corresponding transfer parameters for the studied IL from water to the aqueous tri-potassium phosphate solutions. Also, an empirical equation was satisfactorily used to correlate the experimental viscosity data.     

Volumetric and compressibility behaviour of poly(propylene glycol) – Amino acid aqueous solutions at different temperatures

Precise density and sound velocity measurements have been carried out for aqueous solutions of PPG725 in the absence and presence of (0.2 and 0.5) mol · kg⁻¹ amino acids: alanine, glycine, serine and proline, and also for aqueous solutions of these amino acids in the absence and presence of 0.01 w/w PPG725 at T = (288.15, 293.15, 298.15, 303.15 and 308.15) K. From the experimental density and sound velocity values, the apparent molar volume and isentropic compressibility have been obtained and extrapolated to infinite dilution. The infinite dilution apparent molar properties for transfer of PPG from water to aqueous amino acids solutions and also those for transfer of amino acids from water to aqueous PPG solutions have been studied. Temperature dependency of the infinite dilution apparent molar volume was utilised to determine structure-breaker or structure-maker effects of the solutes. Hydration numbers of the amino acids in the investigated aqueous solutions have been evaluated from the volumetric and compressibility properties. All results are discussed based on the salting-out aptitude of the amino acids (hydrophilic + hydrophobic) interactions and (hydrophobic + hydrophobic) interactions occurred between PPG and the investigated amino acids.     

Apparent molar volumes and compressibilities of electrolytes and ions in γ-butyrolactone

The densities of tetraphenylphosphonium bromide, sodium tetraphenylborate, lithium perchlorate, sodium perchlorate and lithium bromide in γ-butyrolactone at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and speed of sound at 298.15 K have been measured. From these data apparent molar volumes V_Φ at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and the apparent molar isentropic compressibility K_S,Φ, at T = 298.15 K of the salts have been determined. The apparent molar volumes and the apparent molar isentropic compressibilities were fitted to the Redlich, Rosenfeld and Mayer equation as well as to the Pitzer and Masson equations yielding infinite dilution data. The obtained limiting values have been used to estimate the ionic data of the standard partial molar volume and the standard partial isentropic compressibility in γ-butyrolactone solutions.     

(Vapour + liquid) equilibria,volumetric and compressibility behaviour of binary and ternary aqueous solutions of 1-hexyl-3-methylimidazolium chloride,methyl potassium malonate,and ethyl potassium malonate

(Vapour + liquid) equilibrium data (water activity, vapour pressure, osmotic coefficient, and activity coefficient) of binary aqueous solutions of 1-hexyl-3-methylimidazolium chloride ([C₆mim][Cl]), methyl potassium malonate, and ethyl potassium malonate and ternary {[C₆mim][Cl] + methyl potassium malonate} and {[C₆mim][Cl] + ethyl potassium malonate} aqueous solutions were obtained through the isopiestic method at T = 298.15 K. These results reveal that the ionic liquid behaves as surfactant-like and aggregates in aqueous solutions at molality about 0.4 mol · kg⁻¹. The constant water activity lines of all the ternary systems investigated show small negative deviations from the linear isopiestic relation (Zdanovskii–Stokes–Robinson rule) derived using the semi-ideal hydration model. The density and speed of sound measurements were carried out on solutions of methyl potassium malonate and ethyl potassium malonate in water and of [C₆mim][Cl] in aqueous solutions of 0.25 mol · kg⁻¹ methyl potassium malonate and ethyl potassium malonate at T = (288.15 to 308.15) K at atmospheric pressure. From the experimental density and speed of sound data, the values of the apparent molar volume, apparent molar isentropic compressibility and excess molar volume were evaluated and from which the infinite dilution apparent molar volume and infinite dilution apparent molar isentropic compressibility were calculated at each temperature. Although, there are no clear differences between the values of the apparent molar volume of [C₆mim][Cl] in pure water and in methyl potassium malonate or ethyl potassium malonate aqueous solutions, however, the results show a positive transfer isentropic compressibility of [C₆mim][Cl] from pure water to the methyl potassium malonate or ethyl potassium malonate aqueous solutions. The results have been interpreted in terms of the solute–water and solute–solute interactions.     

Isothermal compressibility and internal pressure studies of some non-electrolytes in aqueous solutions at low temperatures

The experimental data of density (ρ) and sound velocity (u) in the temperature range (275.15 to 293.15) K have been obtained for the systems (dioxane + water), (dimethylformamide + water), (tetrahydrofuran + water), and (acetonitrile + water). The specific heat (C_p) data for the above systems have been obtained at T = 279.15 K. The data obtained are used to calculate the derived parameters of adiabatic compressibility (β_S), at T = 275.15 K to T = 283.15 K, isothermal compressibility (β_T), and internal pressure (P_i) at T = 279.15 K for different concentrations. The solute properties: apparent molar volume (ϕ_V), apparent molar expansivity (ϕ_E), and apparent molar compressibility (ϕ_KS) have been studied and the limiting values for these properties are reported. The variation in apparent molar properties with concentration and the corresponding temperature and pressure effects are discussed in terms of hydrophobic hydration (–H bonding interaction) and hydrophobic interaction (non-polar group solute–solute association in water). It is noted that the internal pressure of solutions is quite insensitive in the region of solute–solute association, while its variation with concentration in the dilute region is sensitive in contrast to the aqueous alcohol solutions. The molecular interactions also exhibit individualistic behaviour and are much dependent on structural alterations in water structure.     

Effect of temperature on solvation behaviour of diclofenac sodium salt in aqueous glycine and l-proline solutions

Apparent molar volume (V_2,ϕ) and apparent molar isentropic compressibility (K_s,2,ϕ) of diclofenac sodium salt (DSS) drug within the concentration range of (0.001 to 0.008) mol · kg⁻¹ in (0.01, 0.03 and 0.05) mol · kg⁻¹ aqueous glycine and l-proline solutions are computed from the experimental density (ρ) and speed of sound (u) values at T = (293.15 to 313.15) K and atmospheric pressure. Derived parameters such as partial molar properties, transfer partial molar properties, hydration numbers and Hepler’s constant are computed from the data of V_2,ϕ and K_s,2,ϕ. These parameters have been used to understand the effect of temperature on interactions between DSS drug and aqueous glycine/l-proline solution. Furthermore, the structure making and breaking ability of DSS drug in probed solutions are analysed at experimental conditions.     

Effect of temperature and ionic strength on volumetric and acoustic properties of solutions of urea alkyl derivatives in aqueous NaCl

The present work was undertaken to study volumetric and acoustic properties for diluted solutions of tetramethylurea in pure water and for urea, n-propylurea, n-butylurea and tetramethylurea in 0.5 or 1 mol · dm⁻³ aqueous solutions of sodium chloride. This paper presents measured values of densities and sound velocities at T = (288.15, 298.15 and 308.15) K. From these data the apparent molar volumes, V_Φ, adiabatic compressibilities, κ_S, and apparent molar adiabatic compressions, K_S,Φ, were obtained. The values of apparent molar volumes for infinite dilution and limited apparent adiabatic compressions were calculated from extrapolation of the concentration dependence. Further, the corresponding transfer data as well as hydration number of urea and its derivatives in the studied systems were estimated. The obtained parameters are discussed in terms of various solute-solvent and solute-cosolute interactions.     

Excess parameters of binary mixtures of anisaldehyde with o-cresol,m-cresol and p-cresol at T = (303.15, 308.15, 313.15, and 318.15) K

The density, ultrasonic velocity, and viscosity of binary mixtures of (anisaldehyde + o-cresol, or +m-cresol, or +p-cresol) have been measured over the entire range of composition at T = (303.15, 308.15, 313.15, and 318.15) K. Using these data, various thermo-acoustic parameters such as deviation in adiabatic compressibility, Δβ, excess molar volume, V^E, viscosity deviation, Δη and excess Gibb’s free energy of activation for viscous flow, ΔG^1E have been calculated. The calculated deviation and excess functions have been fitted to the Redlich–Kister polynomial equation. The negative and positive values of deviation or excess thermo-acoustic parameters observed have been explained on the basis of the intermolecular interactions present in these mixtures.     

Effect of KCl on the volumetric and transport properties of aqueous tri-potassium citrate solutions at different temperatures

Density, speed of sound and viscosity measurements of binary aqueous solutions of tri-potassium citrate were performed from dilute up to near saturated concentration range at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K. Volumetric and transport properties of ternary aqueous solutions of (tri-potassium citrate + KCl) have also been measured within the molality range of KCl (0.05, 0.15, 0.25, 0.35, 0.45, and 0.55) at different temperatures. Apparent molar volume and apparent molar isentropic compressibility have been calculated from the density and speed of sound for binary and ternary aqueous solutions of tri-potassium citrate. Apparent molar volume and apparent molar isentropic compressibility of ternary aqueous solutions of (tri-potassium citrate + KCl) have been correlated with the Redlich–Mayer equation. Viscosity values of ternary aqueous solutions of (tri-potassium citrate + KCl) have been fitted with the Jones–Dole equation. The results obtained have been interpreted in elucidating the effect of tri-potassium citrate on the interaction of KCl–H₂O. Density and viscosity values of ternary aqueous solutions of (tri-potassium citrate + KCl) have been predicted successfully using the methods proposed by Laliberte (2007), Laliberte and Cooper (2004) [9], [10] and Zafarani-Moattar and Majdan-Cegincara (2009) [11].     

Densimetric and ultrasonic characterization of pentaerythritol in water and in aqueous NaCl and MgCl2 solutions at different temperatures

The densities at T = (293.15, 298.15, 303.15, 308.15, 310.15, and 313.15) K and sound velocities at T = (298.15 and 310.15) K have been measured for pentaerythritol in pure water and in (1, 5, and 10) wt% aqueous solutions of sodium and magnesium chloride. From these data apparent molar volumes, V_Φ, and the apparent molar isenotropic compressibilities, K_S,Φ, of the polyol have been determined. The limiting apparent molar quantities and corresponding transfer parameters were also obtained and discussed in terms of various solute–solvent and solute–cosolute interactions.     

Partial molar volume and isentropic compressibility of symmetrical and asymmetrical quaternary ammonium bromides in aqueous solution

Values of apparent molar volume and isentropic compressibility of symmetric and asymmetric isomers of tetrabutylammonium bromide, namely tetra-n-butylammonium bromide, tetra-iso-butylammonium bromide, tetra-sec-butylammonium bromide, di-n-butyl-di-iso-butylammonium bromide and di-n-butyl-di-sec-butylammonium bromide, in aqueous solution were determined from density and speed of sound measurements. These properties were obtained as a function of molal concentration within the range of 0.01 < m/mol · kg⁻¹ < 0.1 covering temperatures from 278.15 ⩽ T/K ⩽ 293.15. The partial molar volumes and the apparent isentropic molar compressibility at infinite dilution were calculated and their dependence on temperature examined. The results show that cations with sec-butyl chains have larger structural volumes compared to those with iso-butyl chains. In addition, cations with sec-butyl chains induce smaller structural changes in their hydration shell than the others.     

Adiabatic compressibility of pseudo-binary aqueous solutions of tert-butyl alcohol and dimethylsulfoxide as a result of ultrasonic investigations

The tert-butyl alcohol (TBA) and dimethyl sulfoxide (DMSO) are two small molecules geometrically very similar, but having different polar groups. Taking into account the intermolecular interactions in the TBA/H₂O and DMSO/H₂O systems, especially in the water-rich region of concentration, the ultrasonic speeds (high accuracy resonance method at the frequency 7.5 MHz) and densities in pseudo-binary mixtures of the system: (TBA + H₂O + DMSO) with the ratio (TBA + DMSO)/H₂O = 1/25 have been measured. From these data, various thermodynamical parameters such as adiabatic compressibility, molar volume, thermal expansivity, and the deviation from reference system have been calculated. In addition, the isobaric molar heat capacity to convert adiabatic compressibility to the isothermal one has been measured. All these parameters have been discussed to explain solute–solvent and solute–solute interactions, especially the effect of the complexation process between TBA and DMSO molecules. The composition dependence of these deviations functions was interpreted in the light of the mixing schemes in the aqueous solutions of TBA and DMSO.     

Solvation of ionic liquids based on N-methyl-N-alkyl morpholinium cations in dimethylsulfoxide – volumetric and compressibility studies

The density and sound velocity of the solutions of ionic liquids based on N-alkyl-N-methyl-morpholinium cations, N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-methyl-N-octyl-morpholinium bis(trifluoromethanesulfonyl)imide and N-decyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide in dimethylsulfoxide were measured at T = (298.15 to 318.15) K and at atmospheric pressure. The apparent molar volume and apparent molar compressibility values were evaluated from density and sound velocity values and fitted to the Masson equation from which the partial molar volume and partial molar isentropic compressibility of the ILs at infinite dilution were also calculated at working temperatures. By using the density values, the limiting apparent molar expansibilities were estimated. The effect of the alkyl chain length of the ILs and experimental temperature on these thermodynamic properties is discussed. In addition, molecular dynamics simulations were used to interpret the measured properties in terms of interactions of ILs with solvent molecules. Both, volumetric measurements results and molecular dynamics simulations for ionic liquids in dimethylsulfoxide were compared and discussed with results obtained for the same IL in acetonitrile.     

Excess molar volumes and isentropic compressibility of binary systems {trioctylmethylammonium bis(trifluoromethysulfonyl)imide + methanol or ethanol or 1-propanol} at different temperatures

This paper reports measurements of densities for the binary systems of an ionic liquid and an alkanol at T = (298.15, 303.15, and 313.15) K. The IL is trioctylmethylammonium bis(trifluoromethylsulfonyl)imide [OMA]⁺[Tf₂N]^? and the alkanols are methanol, or ethanol, or 1-propanol. The speed of sound at T = 298.15 K for the same binary systems was also measured. The excess molar volumes and the isentropic compressibilities for the above systems were then calculated from the experimental densities and the speed of sound, respectively. Redlich–Kister smoothing polynomial equation was used to fit the excess molar volume and the deviation in isentropic compressibility data. The partial molar volumes were determined from the Redlich–Kister coefficients. For all the systems studied, the excess molar volumes have both negative and positive values, while the deviations in isentropic compressibility are negative over the entire composition range.     

Thermodynamic properties of solutions of sodium di-hydrogen phosphate in (1-propanol + water) mixed-solvent media over the temperature range of (283.15 to 303.15) K

The apparent molar volume and apparent molar isentropic compressibility of solutions of sodium di-hydrogen phosphate (NaH₂PO₄) in (1-propanol + water) mixed-solvent media with alcohol mass fractions of 0.00, 0.05, 0.10, and 0.15 are reported over the range of temperature (283.15 to 303.15) K at 5 K intervals. The results were fitted to a Redlich–Mayer type equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at the infinite dilution were also calculated at the working temperature. The results show a positive transfer volume of NaH₂PO₄ from an aqueous solution to an aqueous 1-propanol solution. The apparent molar isentropic compressibility of NaH₂PO₄ in aqueous 1-propanol solutions is negative and it increases with increasing the concentration of NaH₂PO₄, 1-propanol, and temperature. Electrical conductivity and refractive index of the solutions are also studied at T = 298.15 K. The effects of the electrolyte concentration and relative permittivity of the medium on the molar conductivity were also investigated.     

Apparent molar volumes and compressibilities of tetrabutyl-ammonium bromide in organic solvents

The densities of tetra-n-butylammonium bromide in 1-propanol, 1-butanol, acetone at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and sound velocities at 298.15 K have been measured. From these data apparent molar volumes V_Φ at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and the apparent molar isenotropic compressibility K_S,Φ, at T = 298.15 K of tetrabutylammonium bromide in nonaqueous solvents have been determined. The apparent molar volumes and the apparent molar isenotropic compressibilities were fitted to the Redlich, Rosenfeld, and Mayer equation as well as to the Pitzer equation yielding infinite dilution data, which were compared to the similar quantities for tetrabutylphosphonium bromide. Moreover, the acoustical parameters such as intermolecular free length (L_f), relative association (R_A), Rao’s molar sound function (R_m), and salvation number (S_n) were calculated using the experimental data of density and sound velocity at T = 298.15 K for ammonium and phosphonium bromides. The obtained data suggest the penetration of the acetone molecule within the intraionic free space of the tetrabutyl-ammonium and phosphonium cations.     

Thermodynamic properties of (tetradecane + benzene, + toluene, + chlorobenzene, + bromobenzene, + anisole) binary mixtures at T = (298.15, 303.15, and 308.15) K

Density ρ, viscosity η, and refractive index n_D, values for (tetradecane + benzene, + toluene, + chlorobenzene, + bromobenzene, + anisole) binary mixtures over the entire range of mole fraction have been measured at temperatures (298.15, 303.15, and 308.15) K at atmospheric pressure. The speed of sound u has been measured at T = 298.15 K only. Using these data, excess molar volume V^E, deviations in viscosity Δη, Lorentz–Lorenz molar refraction ΔR, speed of sound Δu, and isentropic compressibility Δk_s have been calculated. These results have been fitted to the Redlich and Kister polynomial equation to estimate the binary interaction parameters and standard deviations. Excess molar volumes have exhibited both positive and negative trends in many mixtures, depending upon the nature of the second component of the mixture. For the (tetradecane + chlorobenzene) binary mixture, an incipient inversion has been observed. Calculated thermodynamic quantities have been discussed in terms of intermolecular interactions between mixing components.     

Thermodynamic and optical studies of some ethylene glycol ethers in aqueous solutions at T = 298.15 K

Experimental results of density (ρ), speed of sound (u), and refractive index (n_D) have been obtained for aqueous solutions of ethylene glycol monomethyl ether (EGMME), ethylene glycol monoethyl ether (EGMEE), diethylene glycol monomethyl ether (DEGMME), and diethylene glycol monoethyl ether (DEGMEE) over the entire concentration range at T = 298.15 K. From these measurements, the derived parameters, apparent molar volume of solute (?_V), excess molar volume (V^E), isentropic compressibility of solution (β_S), apparent molar isentropic compressibility of solute (?_KS), deviation in isentropic compressibility (Δβ_S), molar refraction [R]_1,2 and deviation in refractive index of solution (Δn_D) have been calculated. The Redlich–Kister equation has been fitted to the calculated values of V^E, Δβ_S and Δn_D for the solution. The results obtained are interpreted in terms of hydrogen bonding and various interactions among solute and solvent molecules.     

Density,speed of sound,and refractive index measurements for the binary systems (butanoic acid + propanoic acid,or 2-methyl-propanoic acid) at T = (293.15 to 313.15) K

Density, speed of sound, and refractive index for the binary systems (butanoic acid + propanoic acid, or 2-methyl-propanoic acid) were measured over the whole composition range and at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K. The excess molar volumes, isentropic compressibilities, excess isentropic compressibilities, molar refractions, and deviation in refractive indices were also calculated by using the experimental densities, speed of sound, and refractive indices data, respectively. The Redlich–Kister smoothing polynomial equation was used to fit the excess molar volume, excess isentropic compressibility and deviation in refractive index data. The thermodynamic properties have been discussed in terms of intermolecular interactions between the components of the mixtures.