Partial Molar Volumes Of Transfer Research Articles

Thermo-acoustic properties of monosaccharides D(−)-ribose and D(+)-xylose in aqueous diammonium hydrogen phosphate solutions at different temperatures

The volumetric and acoustic properties are used for investigating the interactions of polyhydroxy solutes D(−)-ribose and D(+)-xylose in different concentrations of diammonium hydrogen phosphate (DAP) solutions. Densities and speeds of sound of D(−)-ribose and D(+)-xylose in aqueous diammonium hydrogen phosphate (DAP) solutions have been measured over a temperature range of (298.15–318.15) K and at experimental pressure p = 0.1 MPa. Different parameters viz apparent molar volumes, Vϕ, partial molar volumes, apparent molar isentropic compression, partial molar isentropic compression, partial molar volume of transfer and molar isentropic compression of transfer are obtained using experimental density and ultrasonic speed data. The calculated parameters are discussed in rapports of solute–solvent interactions in solutions indicated the presence of ion-ion, ion-polar, hydrophilic-hydrophilic and hydrophobic–hydrophobic interactions in these ternary solutions, which was also confirmed from obtained positive values of apparent molar volume and negative values of apparent molar isentropic compressibility. Pair (VAB, KAB) and triplet (VABB, KABB) interaction coefficients determined by means of McMillan-Mayer theory are used to acquire valuable information about the dominance of pairwise interactions in the studied mixtures.

Volumetric-acoustic study of Disodium Ethylenediaminetetraacetic acid with Propylene and Hexylene glycol at different temperatures

The present study shows the molecular interactions at constant pressure of 0.1 megapascals (MPa) and a range of temperatures from (288.15, 298.15, 308.15, 318.15 K) in aqueous solution of Disodium EDTA in (0.01, 0.02, 0.03) mol.kg-1 along with Propylene glycol and Hexylene glycol. Speed of sound and density data is determined using Anton Paar DSA 5000 M. Various thermo-acoustic parameters are calculated using the obtained data. Experimental density values determined apparent Molar Volume (Vϕ), Partial Molar Volume (Vϕ°) as well as Partial Molar Volume of Transfer (ΔVϕ°) along with Partial Molar Expansibility (Eϕ°) and thermal expansion coefficient (α). While speed of sound determined the Apparent Molar Isentropic Compression (Kϕ,S), Partial Molar Isentropic Compression (Kϕ,S°) as well as Partial Molar Isentropic Compression of Transfer (ΔKϕ.S°). Pair and Triplet Coefficients along with Empirical constants have also been estimated. FTIR spectroscopic research had been carried out in the binary mixture. From propylene through hexylene glycols, these factors provide data related to significant interactions between solute and solvent.

Solute–solvent interactions of glycine, L–alanine, and L–valine in aqueous 1–butyl–3–methylimidazolium methylsulfate ionic liquid solutions at different temperatures

The intermolecular interactions of amino acids (glycine, L–alanine, and L–valine) in aqueous solutions of an ionic liquid, 1–butyl–3–methylimidazolium methylsulfate [Bmim][MeSO4] as a function of temperature have been investigated by combination of volumetric and acoustic methods. The density, ρ, and speed of sound, u, of glycine, L–alanine and L–valine in aqueous 1–buytl–3–methylimidazolium methylsulfate solutions have been measured in the temperature interval T = (288.15, 298.15, and 308.15) K and atmospheric pressure. These data have been used to calculate apparent molar volume (V∅), and apparent molar adiabatic compressibility (K∅,s) of these mixtures at different temperatures. Later, the standard partial molar volume (V∅0), standard partial molar volumes of transfer (ΔV∅0), standard partial molar adiabatic compressibility (K∅,s0), and standard partial molar adiabatic compressibility (ΔK∅,s0) of transfer have been determined for these amino acid solutions from density and speed of sound data. Also, hydration number (nH) and various group contribution have been calculated. Finally the results have been interpreted in terms of solute - solvent interactions that exist among the currently investigated systems.

Evolution of solute–solvent interactions for aqueous 1-decyl-3-methylimidazolium bromide, [C10mim] [Br] solutions containing glycine/ glycylglycine through volumetric and acoustic studies

• New experimental density and speed of sound data have been collected. • Glycine/glycylglycine thermodynamic properties behaviour in aqueous IL has been examined. • Pair and Triplet interaction coefficient define the solute solvent interactions • The potential of co-solute to make and break structures has been interpreted. Volumetric and compressibility characteristics of ternary systems have been examined at temperatures T = 288.15 K−318.15 K at interval of 10 K and atmospheric pressure using vibrating tube densitometer DSA 5000 in order to investigate the interactions present in aqueous {glycine/glycylglycine + ionic liquid 1-decyl-3-methylimidazolium bromide} solutions. Using the experimental data for density, partial molar volume of transfer ( Δ V ϕ 0 ), limiting apparent molar volume ( V ϕ 0 ) have been computed. On the other hand speed of sound data utilized to calculate partial molar isentropic compression of transfer ( Δ K ϕ , S 0 ) and limiting apparent molar isentropic compression ( K ϕ , s 0 ). The ternary system's apparent molar and partially molar volumetric characteristics show that solute-solvent interactions prevail. The pair and triplet interaction coefficients determined from partial molar volumes of transfer and partial molar isentropic compression of transfer provide an explanation for the dominance of paired interactions.

Study on the interactions of tetradecylpyridinium dl-mandelic acid and cetylpyridinium dl-mandelic acid with some small biomolecules in aqueous solution

Interactions of two active pharmaceutical ingredient ionic liquids (API-ILs) tetradecylpyridinium dl-mandelic acid ([TetPy][MAN]) and cetylpyridinium dl-mandelic acid ([CetPy][MAN]) with some small biomolecules have been studied by using conductometric, density and UV–vis spectroscopic techniques. The chosen small biomolecules are glycine, l-alanine, l-valine, l-leucine and glycylglycine (AAGG). The critical micelle concentration (cmc) of [TetPy][MAN] and [CetPy][MAN] in aqueous AAGG solution is calculated from the measured conductance values, thus yielding some thermodynamic parameters of the micellization, such as the standard Gibbs energy change (ΔGm0), the standard enthalpy change (ΔHm0) and the standard entropy change (ΔSm0). On the basis of the experimental densities of ternary solutions of (AAGG + API-ILs + water), apparent molar volume at infinite dilution (V2,φ0), apparent molar expansibility at infinite dilution (Eφ0), transfer partial molar volume (ΔtV0) and hydration number (nH) of AAGG in aqueous API-ILs solution were calculated. The dominant hydrophobic-hydrophilic and hydrophobic-hydrophobic interactions were involved in the investigated systems. The binding constant (Kb) between AAGG and API-ILs has been calculated from UV–vis spectroscopic data. Effect of some factors including concentration, temperature, molecular structure, etc. on the aforementioned parameters and the existing solvent–solute interaction has been discussed.

Explication of molecular interactions between leucine and pharmaceutical active ionic liquid in an aqueous system: Volumetric and acoustic studies

Ionic liquids and their performance for industrial objectives have focused on some of the most academic and scientific research efforts in the last decade. The densities and sound velocities of amino acid (L-leucine) in an aqueous solution of a pharmaceutically active ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate [BMIm][PF6] were measured at different temperatures (293.15 K to 318.15 K) under atmospheric pressure. The experimental results were further used to compute apparent and partial molar volumes, partial molar expansion, Hepler’s constant, apparent and partial molar isentropic compression, alongwith corresponding empirical constants (Sv and Sk), intermolecular free length Lf and acoustic impedance Z. The negative values are obtained for partial molar volume of transfer, ΔtVΦo at all temperatures, and become more negative by increasing the concentration of ionic liquid which indicates predominance of strong electrostriction. The obtained values of these parameters show the structure-making/breaking ability of leucine in solutions of ionic liquid that favours solute–solvent interactions.

Study of the interactions of monosaccharides D(+)-glucose and D(−)-fructose in aqueous diammonium hydrogen phosphate over the temperature range T=(288.15–318.15) K

The interactions of monosaccharides D(+)-glucose and D(−)-fructose in aqueous solutions of diammonium hydrogen phosphate (DAP) as a function of temperature have been investigated. The values of densities and speeds of sound have been measured for the system of monosaccharides and salt in aqueous solution. Densities and speed of sound for D(+)-glucose and D(−)-fructose in (0.5, 1.0, 1.5 and 2.0) mol⋅kg−1 aqueous solutions of diammonium hydrogen phosphate (DAP) are measured at T = (288.15, 298.15, 308.15 and 318.15) K and experimental pressure p = 0.1 MPa. The apparent molar volume,Vφ the partial molar volume, VφO and standard partial molar volumes of transfer, Δ VφO for D(+)-glucose and D(−)-fructose in aqueous solutions of diammonium hydrogen phosphate (DAP) have been calculated from density data. Apparent molar isentropic compression,Kϕ,s partial molar isentropic compression, Kϕ,so and partial molar isentropic compression of transfer, ΔKϕ,so have been calculated from speed of sound measurements. The expansibility parameter (∂Vϕ0 /∂T)p and its derivative (∂2 Vϕ0 /∂2 T)p along with pair (VAB, KAB) and triplet (VABB, KABB) interaction coefficients have also been calculated. The results have been interpreted in terms of solute − solute and solute–solvent interactions prevailing in these ternary systems.

Volumetric and acoustic properties of L-phenyl glycine and L-phenylalanine in aqueous solution of 1-dodecyl-3-methylimidazolium bromide [C12mim] [Br

To study the molecular interactions between the ternary mixtures containing long chain imidazolium based ionic liquid as a common solvent with substituted amino acids L-phenyl glycine and L-phenylalanine respectively, densities and speed of sound have been measured at three different temperatures viz. T = 288.15 K, 298.15 K, 318.15 and 318.15 K under 0.1 MPa pressure. The density and speed of sound data have been further utilized to calculate the apparent molar volume and apparent molar isentropic compression. From the data obtained, apparent molar volume (Vϕ), partial molar volume (Vϕ0), and standard partial molar volumes of transfer (ΔVϕ0). Positive values of apparent molar volume indicate strong interactions. Also, partial molar isentropic compression of transfer (ΔKϕ,S0) and partial molar isentropic compression (Kϕ,s) have been calculated from the sound of speed. Furthermore, structure making and structure breaking ability of solute have been discussed by evaluation of apparent molar expansivity, (ϕE0), Hepler's constant values ∂/∂Tp. The obtained results have been discussed in terms of solvation behavior, structural changes and various interactions present in different ternary mixtures (1-dodecyl-3-methylimidazolium bromide + amino acids + water).

Volumetric, acoustic and viscometric studies of solute-solute and solute-solvent interactions of glycine and its peptides in aqueous solutions of an antidepressant drug at different temperatures

From the density (ρ), speed of sound (u) and viscosity (η) measurements, the interactions of glycine, glycylglycine and glycylglycylglycine with antidepressant drug, nortriptyline hydrochloride have been investigated in aqueous medium at temperatures, T = (293.15–313.15) K and experimental pressure p = 0.1 MPa. From the experimental density measurements, apparent molar volume (VΦ), limiting apparent molar volume (VoΦ) and partial molar volumes of transfer (VoΦ,tr) have been determined for various solutions of glycine, glycylglycine and glycylglycylglycine in aqueous nortriptyline hydrochloride. In addition, using speed of sound data, apparent molar isentropic compression (Ks,Φ), limiting apparent molar isentropic compression (Kos,Φ) and partial molar isentropic compression of transfer (Kos,Φ,tr) have been calculated. Pair and triplet interaction coefficients are also determined from VoΦ,tr values using McMillan-Mayer theory. Further, apparent molar expansibility (EoΦ) and Hepler's constant values ∂EoΦ∂TP have been evaluated to assist the interpretations earned from the volumetric and acoustic analysis. The viscosity coefficients A and B, viscosity B-coefficient of transfer (Btr) and temperature derivative of B-coefficients (dB/dT) have been determined from viscosity data. The results were interpreted in terms of different kinds of intermolecular interactions present in the ternary systems (amino acid/peptides + water + nortriptyline hydrochloride) through a cosphere overlap model. The Hepler’s constant and temperature derivative of B-coefficients (dB/dT) confirms the structure breaking nature of the solute.

Thermophysical studies of protonated and deprotonated glycine in aqueous sodium acetate buffer solutions at different temperatures

Interactions of glycine in water and in (0.10, 0.50 and 1.00) aqueous sodium acetate buffer solutions of pH (1.00 and 12.40) have been investigated at different temperatures, T/K = (298.15-318.15). Densities, and viscosities, of glycine in water and in aqueous sodium acetate buffer solutions have been measured. The obtained density data have been used to calculate apparent molar volume, , limiting partial molar volume, , limiting partial molar volumes of transfer, . Viscosity B-coefficient, viscosity B-coefficient of transfer, , Activation free energies per mole of the solute, and solvent, have been calculated from viscosity data. Further, second order derivative of partial molar expansion coefficient and dependence of coefficients on temperature is useful in measuring the structure making and breaking behavior of solute in these systems. Pair and triplet interaction coefficients for both the properties were also calculated. Thus, the results obtained from volumetric and viscometric studies are of considerable importance to identify different type of interactions (i.e. H-bonding, van der Waal’s interactions)in these systems.

Solvation properties of l-lysine and l-arginine in aqueous solutions of 1-heptyl-3-methyl imidazolium tetrafluoroborate [C7mim][BF4]at different temperatures

Thermodynamic and physicochemical properties of lysine and arginine in aqueous and aqueous solution of 1-heptyl-3-methyl imidazolium tetrafluoroborate [C7mim][BF4] have been studied by measuring density and speed of sound data at T = (288.15–308.15 K) under atmospheric pressure. The measured data has been further used to calculate limiting partial molar volume, Vϕ0 , the limiting partial molar compression Kϕ,S0 , and limiting partial molar volumes of transfer, ΔtrVϕ0,and limiting partial molar isentropic compression of transfer ΔtrKϕ,S0 . Furthermore, structure making and structure breaking ability of solute has been discussed by evaluation of apparent molar expansivity, Eϕ0 , Hepler's constant values, ∂Eϕ0∂TP and hydration numbers, nH .

Thermophysical properties of amino acids L-serine and L-leucine in aqueous diammonium hydrogen phosphate solutions: Volumetric and acoustic studies

Densities and speeds of sound measurements have been done for the amino acids (AAs) L-serine and L-leucine in aqueous diammonium hydrogen phosphate (DAP) solution at different temperatures with a specific interval of temperature. Thermophysical parameters including apparent molar volume (Vϕ), partial molar volume (Vϕ0), apparent molar isentropic compression (Kϕ,s), partial molar isentropic compression (Kϕ,s0) and transfer volumes like partial molar volumes of transfer (ΔVϕ0) and partial molar isentropic compression of transfer (ΔKϕ,so) were determined using the measured experimental data. The co-sphere overlap model was used to interpret the sort of interactions dominating in the system. The obtained transfer quantities are positive which indicates the dominance of ion-hydrophilic and hydrophilic–hydrophilic interactions existing among the amino acids and diammonium hydrogen phosphate salt solution in aqueous medium. Pair and triple interaction coefficients calculated for the system of amino acids and phosphate salt in aqueous medium. Overall results have been elaborated in terms of the solute-solvent or solute-solute interactions prevailing in the system.

Some thermodynamic properties and computational study of DESs (choline chloride/ethylene glycol and choline chloride/malonic acid) in lithium nitrate + propylene carbonate solutions at T = 298.15 K

Deep eutectic solvents (DESs) with propylene carbonate represent an appealing alternative for organic solvents and ionic liquids to dissolve lithium salts. The present research reports the effect of deep eutectic solvents {DESs (choline chloride/ethylene glycol with the molar ratio of 1.00:2.00) and (choline chloride/malonic acid with the molar ratio of 1.00:1.00) on the thermodynamic and transport properties of solutions of lithium nitrate (LiNO3) in propylene carbonate (PC). To evaluate solute–solvent interactions in the above systems first the volumetric, ultrasonic, and viscometric properties were studied. For this purpose, the density (d), speed of sound (C) and viscosity (η) were measured for the binary solutions of (LiNO3 + PC) and quaternary solutions containing (LiNO3 + PC) and DES in different mass fraction of, w = (0.05, 0.010, 0.015 and 0.020), at 298.15 K under ambient pressure. The measured data were used for calculation of the apparent molar volume (Vφ), standard partial molar volume (Vφ0), apparent molar isentropic compressibility (κϕ), partial molar isentropic compressibility (κφ0), partial molar volumes of transfer (ΔtrVφ0) and viscosity B-coefficient of (LiNO3 + PC + DES) solutions. Then, to evaluate the interaction energies, the density functional theory (DFT) of LiNO3 with DESs in PC has also been studied. The thermodynamic and transport investigations indicated that the choline chloride/ethylene glycol interactions are more favorable than choline chloride/malonic acid with LiNO3 in the presence of PC. Generally, the additions of these DESs on the solution of LiNO3 + PC lead to enhancing of the solute–solvent interactions. Also, the DFT results revealed that the interaction between the ChCl/EG with LiNO3 in PC is stronger than ChCl/MA with LiNO3 in PC confirming the result deduced from our experimental studies.

Interaction studies of diglycine with aqueous solutions of sulphathiazole drug at different temperatures

The interactions of diglycine with sulphathiazole drug as a function of temperatures have been studied using volumetric and acoustic parameters. Densities and speeds of sound of diglycine in (0.001, 0.002,0.005, and 0.010) mol·kg-1 aqueous solutions of sulphathiazole drug have been measured at five different temperatures of (288.15,293.15,298.15,303.15 and 308.15) K under 0.1MPa pressure. From density data, the apparent molar volume (Vf), the partial molar volume ( ) and the standard partial molar volume of transfer ( ) for glycine from water to aqueous sulphathiazole solutions have been calculated. Partial molar isentropic compression and partial molar isentropic compression of transfer ( ) have been calculated from the speed of sound data. Transfer parameters by using cosphere overlap model have been explained from the point of view of concentration dependence of solute-solute and solute-solvent interactions. To draw the conclusion from the volumetric and acoustic data, limiting apparent molar expansion , as well as hydration numbers, have been studied. The calculated values of thermal expansion coefficient, , have small and positive values. All of these derived or calculated parameters are explained to understand the solvation behavior, mixing aspects and various types of interactions born in the ternary solutions of (drug + water + dipeptide) due to change in structure. We have also attempted to examine the temperature and concentration dependence of such interactions.

Effect of choline chloride based deep eutectic solvents on lithium perchlorate + propylene carbonate solutions: Thermodynamic, transport, electrochemical and computational study

BackgroundThe influence of deep eutectic solvents (DESs) {(choline chloride (ChCl): lactic acid (LA) and choline chloride: malonic acid (MA)} with different mass fractions of DES on the thermodynamic, transport and electrochemical properties of lithium perchlorate (LiClO4) in propylene carbonate (PC) systems were studied. These investigations are in line with proposing new green electrolyte solutions for future electrochemical applications. MethodsDensity, speed of sound and viscosity at T = 288.15–318.15 K of (LiClO4 + PC + DESs) solutions have been measured from which the apparent molar volume, apparent molar isentropic compressibility, standard partial molar volume, partial molar isentropic compressibility, partial molar volumes of transfer, partial molar isentropic compressibility of transfer and viscosity B-coefficient were calculated. Also density functional theory (DFT) of LiClO4 with DESs in PC solvent was applied. As well as linear sweep voltammetry (LSV) measurements were performed. Significant findingsThe calculated thermodynamic and transport parameters indicated that interactions of ChCl/LA with LiClO4 in the presence of PC are more favorable than ChCl/MA. Then, the DFT was applied to find further evidence for these solute-solvent interactions and confirmed the thermodynamic and transport results. Finally, LSV measurements were performed for investigating the electrochemical potential windows of the systems.

Molecular Interactions of Diphenhydramine-hydrochloride with Some Imidazolium-Based Ionic Liquids in Aqueous Media at T = 293.15-313.15 K: Volumetric, Acoustic, and UV Absorption Studies.

From the density (ρ) and speed-of-sound (u) measurements, the interactions of the drug diphenhydramine-hydrochloride (DPH) with three imidazolium-based ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C4mim][Cl], 1-hexyl-3-methylimidazolium chloride1, [C6mim][Cl], and 1-methyl-3-octylimidazolium chloride, [C8mim][Cl]) have been investigated in aqueous medium at T = 293.15–313.15 K and experimental pressure p = 0.1 MPa. From the density calculations, the apparent molar volume (Vϕ) and the apparent partial molar volumes of transfer (ΔtVϕo) have been determined for various solutions of DPH in aqueous solutions of different ILs. In addition, from the speed-of-sound data, the apparent molar isentropic compressibility (Kϕ), apparent partial molar isentropic compressibility (Kϕo), and apparent partial molar isentropic compressibility of transfer (ΔtKϕο) have been calculated. The pair and triplet interaction coefficients are derived from apparent partial molar volumes of transfer. For the present mixtures, the absorption spectra have been also recorded using a UV–visible spectrophotometer. Using Hepler’s constant, the structure-making nature of the solute has been confirmed. All these calculated parameters provide detailed insights into various physicochemical interactions prevailing in the ternary system and confirm the presence of a strong attractive interaction between DPH and ILs.

Effect of ethylene glycol/diethylene glycol/triethylene glycol on the thermodynamics of the aqueous biotin solutions at various temperatures

Acoustic and volumetric parameters for the liquid mixture (water + Biotin + ethylene glycol/diethylene glycol/triethylene glycol) are evaluated at different temperatures (288.15 K, 298.15 K, 308.15 K, and 318.15 K) and constant pressure of 0.1 MPa over the range of biotin concentrations (0.0000, 0.0015, 0.0025, and 0.0035) mol·Kg-1. The experimental work was carried out by Anton Paar DSA 5000 M, where the density (ρ) and the speed of sound (c) are measured, which are later used to determine the various derived thermodynamic properties, such as, apparent molar properties (apparent molar volume, Vϕ; apparent molar isentropic compression,Kϕ,S), the partial molar properties (partial molar volume, Vϕ0; partial molar isentropic compression, Kϕ,S0), the partial molar transfer properties (partial molar volume of transfer, ΔVϕ0; partial molar isentropic compression of transfer, ΔKϕ,S0) and the partial molar expansibility (Eϕ0) along with its first derivative ∂Eϕ0/∂TP. The obtained results are explained in terms of the kind of intermolecular interactions developed in the mixture using the co-sphere overlap model. Further, with the partial molar properties, the pair and triplet interaction coefficients (VAB,KAB; VABB, KABB) are calculated.

Volumetric Properties of aqueous solutions of Arabinose, Xylose and Galactose in presence / absence of Sodium Cyclamate

Sugars can affect our blood glucose (sugar), weight and blood fats. Synthetic sugars (artificial sweetener) provide little or no calories or carbohydrate or do not increase blood sugar. In food and pharmaceutical industries, blends of sweeteners are commonly used to design the food products and pharmaceutical doses, the information regarding type and extent of sweetener-sweetener and sweetener -water interactions and taste quality of the solution required. The aqueous solutions of arabinose, xylose and galactose with and without cyclamate are studied. Densities of solutions of arabinose, xylose and galactose in presence of 0.05, 0.15 and 0.3 m sodium cyclamate have been measured at 298.15K. Partial molar volumes, apparent specific volumes, partial molar volumes of transfer and doublet and triplet interaction parameters have been calculated. The information obtained from these parameters has been used to understand type and extent of sweetener-sweetener and sweetener -water interactions and taste quality of the solution.

Molecular complexes of polar basic amino acids (l-lysine, l-histidine) with nicotinic acid in water and buffer solution: A thermodynamic aspects

Interactions of the polar basic amino acids, l-lysine (Lys) and l-histidine (His), with heterocyclic ligand, nicotinic acid (NA), in pure water and in phosphate buffer solution (pH 7.4) were studied by calorimetry and densimetry. Under the experimental conditions chosen, thermodynamic parameters of complex formation (lgKc, ΔcG, ΔcH, ΔcS) as well as the hydration enthalpies of different ionized forms of amino acids have been calculated at 298.15 K. The stoichiometry of complexes between Lys/His and NA was determined. The affinity of Lys to binding with NA decreases with increasing pH, the association process being less favorable. The more efficient stabilization of complexes between His and NA was exhibited in buffer media than in water. The apparent molar volumes, partial molar volumes and partial molar volume of transfer of NA from pure solvent (water/buffer) to mixed amino acid solution at infinite dilution have been evaluated. Their values obtained are lower for aqueous solutions than buffer systems. The dependence of thermodynamic characteristics obtained on molecular structure, ionization and hydration state of the solutes was analyzed. The dominant types of driving forces in the complex formation process of polar basic amino acids (Lys, His) with nicotinic acid were found for water and buffer solution.

Temperature-dependent thermodynamic and physicochemical studies of glycols in aqueous biotin solutions

The current study deals with the analysis of the molecular interactions among the glycols (propylene glycol, PG and hexylene glycol, HG) molecules in (0.000, 0.001, 0.002 and 0.003) mol·Kg-1 aqueous solutions of biotin at constant experimental pressure 0.1 MPa and temperature range (288.15 K, 298.15 K, 308.15 K and 318.15 K). The speed of sound and the density for the liquid mixtures is measured with Anton Paar DSA 5000 M. Numerous thermodynamic and acoustic parameters are determined using these experimental data. The apparent molar volume (Vϕ), partial molar volume (Vϕ0), partial molar volume of transfer (ΔVϕ0), apparent molar isentropic compression (Kϕ,S), partial molar isentropic compression (Kϕ,S0), partial molar isentropic compression of transfer (ΔKϕ,S0) were estimated using the experimentally obtained density and speed of sound respectively along with the partial molar expansibility(Eϕ0), its first-order derivative ∂Eϕ0/∂TP and pair-triplet interaction coefficients (VAB,KAB,VABB; KABB). The apparent molar properties recommend the existence of strong (solute and solvent) interactions in the ternary mixture which is also justified by the positive partial molar expansibility values, while the partial molar properties suggest the formation of the hydrogen bond in the mixture. With Passynski's equation the hydration number (nh) for PG/HG in aqueous solutions of biotin is calculated utilizing the compressibility data and the obtained results are explained in terms of combined hydration effects and hydrophobic effect.