Search

Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenylphosphonium bromide- triethylene glycol (ATPPB-TEG) was prepared by using three molar ratios; i.e.,1:4, 1:10, and 1:16 of salt to HBDs. The volumetric properties of aqueous mixture of DESs, such as density, molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temperatures from 293.15 to 343.15 K. A mathematical equation, namely Jouyban–Acree model (JAM), was used to correlate the experimental density and molar volume data. Furthermore, in order to calculate the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich–Mayer equation. By applying Hepler equation, it was found that DESs 1:4 and 1:10 are as structure-maker solutes, while DES 1:16 is a structure-breaking solute in aqueous solutions.

The enthalpies of solution Δ sol H m have been determined for trans -4-hydroxy- l -proline (4-hydroxyproline) in aqueous solutions of formamide (FA), N -methylformamide (MFA), N,N -dimethylformamide (DMF) and N, N -dimethylacetamide (DMA). The measurements have been made at 298.15 K and mole fraction of amide x 2 = (0–0.3) on the precise “isoperobol” calorimeter. The results obtained have been used to calculate the standard enthalpies of solution (Δ sol H °) and transfer (Δ tr H° ) of 4-hydroxyproline from water into mixtures as well as the enthalpic coefficients of pairwise interaction ( h xy ) of 4-hydroxyproline with amides in aqueous solution. The interrelation between enthalpy characteristics of dissolution (transfer) of 4-hydroxyproline and the composition of (water + amide) binary mixtures has been established. Contributions of the amides properties (molar volume, dipolarity/polarizability, acidity, and basicity) to the variation of the energy of pairwise interactions have been estimated quantitatively by means of a modified Kamlet-Taft equation.

Morpholine, having its applications in process industries is also used as an anticancer agent as well as a building block in the preparation of linezolid antibiotic. 1-decanol can be used as a suitable solvent for recovery of morpholine from its aqueous stream. The present study involves VLE studies and volumetric properties of the morpholine + 1-decanol, at 13.32, 39.99, 66.66 and 94.90 kPa. Wilson, NRTL, and UNIFAC models were used to correlate and predict the experimental VLE data. Further, thermodynamic properties such as excess molar volume ( V m E ), and deviation in molar refractivity (ΔR). Partial molar volume ( V ¯ i ), apparent molar volume ( V ϕ i ) and excess partial molar volume ( V ¯ i E ) were also estimated. Moreover, all the above thermodynamic properties have also been estimated for the 1-octanol + toluene mixture at different temperatures. The applicability of Prigogine–Flory–Patterson theory and different mixing rules were tested for the excess molar volumes and refractive indices, respectively.

Ionic liquids analogues known as Deep Eutectic Solvents (DESs) are increasingly realized in many chemical and industrial applications. The physical and chemical characteristics of these fluids are affected considerably by their moisture content. This study focuses on the evaluation and prediction of the density of choline chloride-based DES aqueous mixtures. The study involved six well known DESs with water mole fraction ranging between 0 and 1 within the temperature range (298.15–353.15 K). Since, the density of pure DESs is more than that of water, the resulting aqueous mixtures density trends were similar. The Jouyban-Acree mixture density correlation was adopted for each DES mixture separately with very good prediction accuracy. In addition, an alternative modified model was suggested. This model is capable of predicting all DES mixtures density data based on their corresponding critical properties. Negative excess molar volume suggests formation of stronger H-bond and a more extensive H-bond network within the mixture. This is enhanced by the packing effect created by difference between the molecular structures of the DES and water. The aqueous DES solutions density model presented in this work may assist in evaluating the effect of moisture content on this important physical property. This will further help in adopting proper chemical equipment design considerations and relevant process modeling and simulation calculations.

The density and viscosity of the pure monoethylethanolamine (EMEA), diethylethanolamine (DEEA), H2O components and the binary EMEA (1) +DEEA (2) and EMEA (1) +H2O (2) mixtures were measured from (293.15–333.15) K. The physical and thermodynamic properties of excess molar volume (VE), thermal expansion coefficient (α), viscosity deviation (Δh), activation enthalpy (ΔH), activation entropy (ΔS) and activation molar Gibbs free energy (ΔG) were calculated. The density and viscosity of the pure components as well as the binary mixtures decreased with temperature increasing. The density and viscosity of EMEA, DEEA and H2O followed the orders of H2O > EMEA > DEEA and EMEA > DEEA > H2O, respectively. The density and viscosity decreased with DEEA concentration increasing for EMEA (1) +DEEA (2). In EMEA (1) +H2O (2), the density increased with H2O concentration increasing, while the viscosity increased and then decreased with H2O concentration increasing.

Thermophysical properties of solvent are set of data that are essential for designing processes in industry. But in the absence of experimental data, an accurate predictive method is required. In this context, density (ρ) and viscosity (η) of sulfolane with glycerol and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide have been measured over the entire range of composition with temperature ranging from 298.15 K to 363.15 K at atmospheric pressure. From these experimental values, thermal expansion (α), excess molar volume (VE), viscosity deviation (Δη) and Gibbs free energy (ΔG) were calculated. The predicted values were close to the corresponding experimental data with all the standard deviation lower than 1 × 10−3. Quantum chemical based COSMO-RS was used to predict the molecular interaction and non-ideal liquid phase activity coefficient for all mixtures. It has been interpreted that strong interaction for the sulfolane + [BMIM][NTf2] system, meanwhile weak interaction was deduced for the sulfolane + glycerol system. The molar enthalpy (ΔH), entropy (ΔS) and Gibbs free energy of activation (ΔG) of viscosity were calculated. Simultaneous effects of composition and temperature for the binary mixtures were also reported.

The densities, ρ and refractive index, n D of binary mixtures consisting of bromobenzene, chlorobenzene, nitrobenzene have been measured for the whole range of composition at wide range of temperatures (T = 293.15–333.15 K) in 10 K intervals and their ternary mixture with 1, 2-dichloroethane determined at T = 293.15 K in ambient pressure (81.5 kPa), using Anton Paar DMA 4500 oscillating densimeter and Anton Paar Abbemat 500 automatic refractometer. From experimental data, excess molar volumes V m E for ternary and binary mixtures were derived. Partial molar volumes V i ¯ , apparent molar volumes V ϕ i and refractive index deviations Δ n D of binary mixtures were calculated also and V m E and Δ n D for binary mixtures were correlated with the Redlich–Kister polynomial equation. A comparative study has been made of the refractive indices obtained experimentally and those calculated by means the theoretical relations. Excess molar volume of ternary mixtures were fitted with Cibulka, Singh, and Nagata equations and four geometrical solution models were used to predict excess molar volume of ternary mixtures. Excess molar volumes, V m E , and refractive index deviations, Δ n D are positive for the bromobenzene + nitrobenzene mixtures, while V m E of chlorobenzene +bromobenzene and chlorobenzene +nitrobenzene mixtures are negative and the refractive index deviations Δ n D showed similar behavior. PC-SAFT equations of state were applied to predict density of binary and ternary mixtures and the experimental results of constitute binary mixtures have been used to test the applicability of the Prigogine–Flory–Patterson (PFP) theory.

International audience; The 2,4,6-tris(dimethylaminomethyl)phenol shows a partial miscibility with water. The temperatures of liquid–liquid phase separation were experimentaly determined to establish the phase diagram. The specific heat capacities and densities of aqueous solutions of 2,4,6-tris(dimethylaminomethyl)phenol were measured to determine excess heat capacities and excess molar volume. Experiments have been carried out for temperatures range from 288 K to 338 K, at atmospheric pressure. The NRTL model was used to correlate liquid–liquid equilibria and, the UNIQUAC model to correlate heat capacities and predict excess molar enthalpies. The excess molar volumes were fitted to a Redlich–Kister polynomial.

Accurate density values are reported for binary mixtures of alkoxyalcohols {1-butoxyethanol+ (benzene or cyclohexane)} and {1-methoxy-2-propanol + (benzene or cyclohexane)} over the complete range of alkoxyalcohols composition at temperatures (283.15, 298.15, 323.15 and 343.15) K. Excess molar volumes, V m E for all binary systems were computed from the experimental density data at all investigated temperatures. In all cases density data increased binary with alkoxyalcohols composition, and decreased as temperature increases. The excess molar volumes for all investigated systems were positive at all temperatures. The cyclohexane containing systems shows a nearly symmetric behavior of excess molar volume, whereas the benzene containing systems shows an asymmetric behaviour of the excess molar 2-butoxyethanol and 1-methoxy-2-propanol, respectively. The {1-butoxyethanol + (benzene or cyclohexane)} exhibit a maximum at benzene-rich region and cyclohexane-rich region of the solution respectively. Whereas, {1-methoxy-2-propanol + (benzene or cyclohexane)} systems exhibit a maximum at the equimolar region for the {1-methoxy-2-propanol + cyclohexane} system and at the benzene-rich region for {1-methoxy-2-propanol + benzene}. The results are discussed with regards to the inter-intra molecular interactions amongst the components of the mixtures carried at different composition and temperature.

Flash point. density and viscosity of three binary mixtures containing dicyclopentadiene (DCPD) with methylcyclohexane, toluene and p-xylene were measured in the present work. The experimental data of flash points were compared with the values calculated by Le Chatelier modified equation. Activity coefficients were estimated by the UNIFAC, UNIFAC Dortmund and ASOG models. Also, excess molar volumes, viscosity deviation and excess Gibbs energy of activation of viscous flow were calculated from data of density and viscosity. Prigogine-Flory-Patterson theory was applied to predict V m E . Empirical models were used to predict the viscosity data. NRTL, UNIQUAC and Heil models were applied to calculate G*E. The findings have been employed to examine structural effects and molecular interactions which are dominant between compound molecules. The obtained experimental results showed weak molecular interactions and theory study demonstrated that UNIFAC, PFP, Eyring_NRTL, Lobe, and NRTL were the best models found to fit the flash point, excess molar volume, viscosity and excess free Gibbs energy.

Densities and speeds of sound of the binary liquid mixtures of Ethyl lactate (EL) with 2-methoxyethanol (2-ME), 2-ethoxyethanol (2-EE) and 2-butoxyethanol (2-BE) have been measured over the entire composition range at temperatures of 303.15–318.15 K. From the experimental values excess molar volume ( V m E ) , excess partial molar volume ( V ¯ m , 1 E , V ¯ m , 2 E ), excess partial molar volume at infinite dilution ( v 1 E ) ∞ , ( v 2 E ) ∞ and excess isentropic compressibility ( K s E ) are computed. The variation with the temperature and concentration is discussed in terms of molecular interactions. The excess molar volume and excess isentropic compressibility parameters are fitted to Redlich–Kister polynomial equation to estimate the binary interaction parameters. Thermodynamic studies of the present binary systems reveal strong inter molecular interactions between the unlike molecules. The strength of intermolecular interaction between EL and 2-alkoxyethanol molecules is found to follow the order EL + 2-BE > EL + 2-EE > EL + 2-ME. The FT-IR analysis at various concentrations of these binary mixtures also suggest specific interaction between the unlike molecules and supported thermodynamic findings.

The density (ρ) and the refractive index (n) have been experimentally determined for the ethylbenzene (1)–octane (2)–propylbenzene (3) ternary system in the entire variation range of the composition, at three temperatures: 298.15, 308.15 and 318.15 K and pressure 0.1 MPa. The excess thermodynamic properties that had been calculated based on the experimental determinations have been used to build empirical models which, despite of the disadvantage of having a greater number of coefficients, result in much lower standard deviations in comparison with the Redlich–Kister type models. The statistical processing of experimental data by means of the multiple linear regression method (MLR) was used in order to model the excess thermodynamic properties. Lower standard deviations than the Redlich–Kister type models were also obtained. The adjustment of the excess molar volume (VE) based on refractive index by means of the Multiple linear regression of the SigmaPlot 11.2 program was made for the ethylbenzene (1)–octane (2)–propylbenzene (3) ternary system, obtaining a simple mathematical model which correlates the excess molar volume with the refractive index, the normalized temperature and the composition of the ternary mixture: VE = A0 + A1X1 + A2X2 + A3(T/298.15) + A4n for which the standard deviation is 0.03.

The enthalpies of l -methionine dissolution in aqueous solution of acetonitrile, 1,4-dioxane, acetone, dimethylsulfoxide, formamide, N-methylformamide, N,N-dimethylformamide and N,N-dimethylacetamide were determined by calorimetric method at 298.15 K and organic solvent mole fractions up to x2 ∼ 0.35. The standard enthalpies of solution (ΔsolH°) and transfer (ΔtrH°) of l -methionine from water to a mixed solvent as well as the enthalpy coefficients of pairwise interactions (hxy) were calculated. The interrelation between enthalpy characteristics of l -methionine dissolution (transfer) and the composition of water–organic mixtures was determined. Contributions of the organic solvent properties (molar volume, cohesion energy density, polarity/polarizability, acidity and basicity) to the energy of pairwise interactions of l -methionine – organic solvent were estimated quantitatively by means of a modified Kamlet-Taft equation. Some characteristics of intermolecular interactions of l -methionine with the molecules of organic solvents were compared with the analogous characteristics of previously investigated amino acids.

Deep eutectic solvents are emerging as potential substitutes for ionic liquids in many chemical and engineering applications. The characterization of physico-chemical properties of these fluids is of high importance for process design and equipment sizing. Despite the few attempts in this area, the huge variety of DES types and structures necessitate the development of models with high prediction quality for calculating their basic physical properties. In this work, molar volume data for common types of DESs was collected as a function of temperature. The Racket model was analyzed and modified to be suitable for DES applications. A modified model was tested and validated with the experimental molar volume DES data. An average percentage deviation of 0.211% was attained. This is about one third the deviation achieved when using the Rackett original model. The newly developed model, can be utilized for predicting molar volume and density in process simulators calculations as well as during the design and operation stages of processes involving the use of DES.

Electrical conductance of lithium perchlorate, sodium perchlorate, potassium perchlorate in pure N-methyl formamide have been measured at 298.15 K. Limiting molar conductance (Λo), association constants (KA) and co-sphere diameter (R) for ion-pair formation have been examined by using Fuoss conductance equation. Viscosity B-coefficient, apparent molar volume ( ϕ V ) and apparent molar adiabatic compressibility ( ϕ K ) have been achieved from viscosity ( η ), density ( ρ ) and speed of sound (c) measurements respectively. The limiting apparent molar volume ( ϕ V 0 ) and experimental slope ( S V * ) have been interpreted in terms of ion–solvent and ion–ion interactions respectively. The viscosity data have been analysed using Jones–Dole equation and derived parameters A and B represent ion–ion and ion–solvent interactions respectively. The c values have been used to determine adiabatic compressibility ( β S ) and limiting apparent molar adiabatic compressibility ( ϕ K 0 ).

Densities (ρ) and ultrasonic speeds (u) for N-acetyl glycine (AG) in (0.05, 0.15, 0.25 and 0.35 mol kg−1) aqueous d -fructose (FR) solutions have been measured at temperatures (288.15, 293.15, 298.15, 303.15 and 308.15) K and at pressure 101 kPa. These data have been used to calculate apparent molar volume (Vϕ) and acoustical parameters, coefficient of isentropic compression (βs), molal hydration number (nH) and apparent molar isentropic compression (Kϕ,s). Partial molar volumes ( V ϕ 0 ) and partial molar isentropic compression ( K ϕ , s 0 ) of AG at infinite dilutions were also evaluated. The partial molar volumes of transfer ( Δ V ϕ 0 ) and partial molar isentropic compression of transfer ( Δ K ϕ , s 0 ) of AG from aqueous to aqueous FR solutions have been calculated and interpreted in terms of solute-co-solute interactions. Pair and triplet interaction coefficients have also been calculated. The results have been used to investigate the solute–solute and solute–solvent interactions as well as the effect of the concentration of FR on these interactions. It is observed that there exist strong solute–solvent interactions in these systems. The data of transfer parameters suggest that the type of interactions present in these systems are complex depending both on the nature of side group as well as on temperature.

This paper reports density, speed of sound, and viscosity data for the bile salts: sodium cholate (1–30 mmol kg−1) and sodium deoxycholate (1–17 mmol kg−1) in 0.1 mol kg−1 aqueous solution of amino acids viz. glycine, leucine, methionine, and histidine at different temperatures (293.15–318.15 K) under atmospheric pressure. From the experimental density and speed of sound data, the apparent molar volume (ϕv), isentropic compressibility (κs), and apparent molar isentropic compression (ϕκ) have been calculated, and the results have been interpreted in terms of different hydrophobic and electrostatic interactions pertaining in the bile salt–amino acid–water ternary system. Based on experimental viscosity data, the relative viscosity (ηr) and viscous relaxation time (τ) have been calculated and their dependence on concentration of bile salts and temperature has confirmed the existence of significant amount of bile salt–amino acid interactions.

Deep eutectic solvents (DESs) are emerging as a new class of biodegradable green solvents; a cost-effective alternative to the conventional room temperature ionic liquids and organic solvents. Hydrophilic nature of DES finds its applications in many industrial and chemical processes. Aqueous mixtures of DESs have potential to afford modified properties for specific applications. A comparative study of densities of two well-known DESs named as ethaline (mixture of choline chloride and ethylene glycol in 1:2 molar ratio) and maline (mixture of choline chloride and malonic acid in 1:2 molar ratio) and their aqueous mixtures in the temperature range 283.15–363.15 K is presented. Decrease in density with increasing temperature is found to follow a quadratic expression. Excess molar volumes of the aqueous mixtures of both ethaline and maline are found to be negative and significant at all temperatures and compositions. Absolute excess molar volume is found to decrease as the temperature is increased from 283.15 K to 323.15 K. For temperature above 323.15 K, the excess molar volume does not change much with further increase in temperature till 363.15 K. The outcomes hint at the presence of relatively stronger interactions, preferably H-bonding type, between water and ethaline/maline, as compared to those among water and among ethaline/maline molecules, respectively. The excess molar volumes at higher temperatures strongly indicate facile interstitial accommodation of water within H-bonded ethaline/maline network to be also present within these aqueous DES mixtures.

Densities (ρ) and speeds of sound (u) of betaine hydrochloride (B.HCl) drug (0.01–0.06) mol kg−1 in (0.10, 0.20 and 0.30) mol kg−1aqueous NaCl and KCl solutions have been reported as a function of temperature at T = (293.15 –313.15) K and at atmospheric pressure. Using experimental data the apparent molar volume (V2,ϕ), partial molar volume (V2∞), transfer partial molar volume (ΔtV2∞), apparent molar isentropic compressibility (Ks,2,ϕ), partial molar isentropic compressibility (Ks,2∞), transfer partial molar isentropic compressibility (ΔtKs,2∞), partial molar expansion (E2∞) and Hepler’s constant (∂2V2∞/∂T2)P were calculated. Further, all these parameters are employed to understand the temperature and cosolute effects on B.HCl drug–solvent interactions. Cosphere overlap model is used to analyze the hydrophilic/ionic-ionic interactions in (B.HCl drug + NaCl/KCl + H2O) ternary mixture. The sign of Hepler’s constant have been used to interpret the structure making or braking tendency of B.HCl drug in aqueous NaCl and KCl solutions at probed compositions and temperatures.

Solute–solvent interaction of the mixtures containing dipeptides of glycine i.e. glycyl–glycine and glycyl-L-leucine with aqueous solutions of antibacterial drug amoxicillin have been studied with the help of density and speeds of sound measurements at T = (305.15, 310.15, and 315.315) K. Apparent molar properties like apparent molar volume, apparent molar isentropic compression have been calculated from experimental data. Partial molar properties of transfer for dipeptides of glycine from water to aqueous amoxicillin solutions have been calculated from density and speeds of sound data. Limiting apparent molar isentropic compression, pair, and triplet interactions coefficients have also been calculated. The UV absorption studies have also been made in this study. The results have been discussed in terms of competing patterns of interactions prevailing in the solute and solvent.

The density and viscosity of binary 1-hexene + 1-octene mixtures have been simultaneously measured over the temperature range from (298 to 470) K and at pressures up to 196 MPa using a hydrostatic weighing and falling-body techniques, respectively. The measurements were made for three concentrations of 0.200, 0.429, and 0.692 mole fraction of 1-octene. The combined expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be (0.15–0.30) %, 0.05%, 0.02 K, and (1.5–2.0) %, respectively, depending on temperature and pressure ranges. The measured densities and viscosities were used to calculate the excess molar volumes and viscosity differences. It is shown that the values of excess molar volume for 1-hexene + 1-octene mixtures are negative, while the viscosity differences are mostly positive at all measured temperatures and pressures over the whole concentration range. The measured densities and viscosities were also used to develop a Tait-type equation of state and viscosity correlation model for liquid 1-hexene + 1-octene mixtures. Theoretically based Arrhenius-Andrade and Grunberg and Nisan type equations were used to represent the temperature and concentration dependences of the measured viscosities for liquid 1-hexene + 1-octene binary mixtures at atmospheric pressure.

Abstact Densities, viscosities, and speeds of sound of the binary liquid mixtures of N-methyl-2-pyrrolidone (NMP) with cyclohexylamine (CHA), cyclohexanol (CHOL) and cyclohexene (CHE) at temperatures of 303.15–318.15 K are measured over the entire composition range. From the experimental values excess molar volume V m E , deviation in isentropic compressibility Δks, excess free length L f E , deviation in viscosity Δη are computed. The variation with the temperature and concentration is discussed in terms of molecular interactions. All the excess parameters and deviations are fitted to Redlich–Kister polynomial equation to estimate the binary interaction parameters and mean deviation from the regression lines. The sign and magnitude of the computed parameters are discussed to reveal the nature and type of interactions existing between the component molecules in the binary mixtures. Thermodynamic investigations under the present study reveal the strong inter molecular interactions between the unlike molecules in the binary systems of NMP + CHA, NMP + CHOL, whereas in the other binary system NMP + CHE the reverse trend is observed due to dispersion forces. The strength of interaction of CHA, CHOL, and CHE with NMP found to follow the order: CHA > CHOL > CHE. FT-IR studies of these mixtures have been estimated and analyzed to study the interactions between unlike molecules. A good agreement is observed between the excess parameters and FT-IR studies.

Densities, ρ, at atmospheric pressure and coefficients of compressibility, k, at p = (10, 25, 50, 75, 100) MPa were measured for aqueous solutions of N,N,N-trimethylglycine (betaine) at T = (278.15, 288.15, 298.15, 308.15 323.15) K. The experimental data have been used to calculate the following volumetric parameters: the apparent molar volume of betaine, Vϕ,2, the molar isothermal compression, KT,m, and the molar isobaric expansion, EP,m, of solutions at all pressures and temperatures studied. Some parameters for infinite dilute solution of betaine in water were also obtained such as limiting partial molar volumes, V 2 ∞ , limiting partial molar isothermal compressions, K T , 2 ∞ , and limiting partial molar isobaric expansions, E P , 2 ∞ . The variation of all these parameters with composition, temperature, and pressure were discussed from the viewpoint of intermolecular interactions in the system.

The speeds of sound and densities of different concentrations of l -tyrosine + l -glutamic acid + water ternary solutions, l -tyrosine + water and l -glutamic acid + water binary solutions at T = (298.15, 308.15, 318.15) K have been measured. Using the densities and the speeds of sound, the apparent molar volumes, the apparent molar isentropic compressibilities, the limiting apparent molar volume, the limiting apparent molar compressibility, the constants ( S V , S , S V , K , S K , S and S K , E ) and the hydration number have been calculated. These parameters have been used to analyze the possible interionic interactions, such as ion–ion, solute–solvent, solvent–solvent, ion–solvent, and solute-co-solute interactions, and are discussed in terms of hydrophobic–hydrophobic, and hydrophilic–hydrophobic group interactions as well as, structure-making and structure-breaking effects in l -tyrosine + l -glutamic acid + water.

This present investigation deals with the effect of antioxidants, viz. butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), on properties of nonionic surfactants, i.e. tert-octylphenol ethoxylate (Triton X-100). Considering the significance of micellar solution as carrier, we examined the transport properties by employing controlled approaches. The positive values of apparent molar volume (ϕν) and apparent molar adiabatic compression (ϕκ) at all temperatures and concentrations are indicative of the existence of hydrophobic interactions. A slight linear increase in viscosity was observed up to a certain concentration of the surfactant and thereafter, a sharp increase confirms the existence of hydrophobic interactions at higher surfactant concentration. Further, from spectroscopic studies, the order of shifting suggests the existence of intermolecular interaction, especially in the hydrophilic region of surfactant. All the studies were found in support of each other with respect to interaction, and would be utilized in different cosmeceutical formulations.

In this paper, we examine density (d), ultrasonic velocity (u) and viscosity studies of SDBS and DTAB in water and in aqueous solutions of 0.01, 0.05, 0.10 mol kg−1 l -glutamine, l -histidine and l -methionine at T = 293.15, 298.15, 303.15, 308.15, 313.15 K. The apparent molar volume (ϕv) dependence on SDBS and DTAB concentration reflects the modification of water–water interactions described as hydrophobic hydration of the surfactant molecules in the presence of amino acid. The trends of apparent molar adiabatic compression (ϕk) values of DTAB with surfactant concentration appear reasonable to suggest that hydrophilic hydration of DTAB–amino acid complex occurs at low surfactant concentration region rendering it to be negative. The gradual increase in viscous relaxation time (τ) with rise in concentration of surfactant and decrease with temperature seem to be happen due to the structural relaxation processes occurring as a result of re-arrangement of molecules.

The density ( d ) and speed of sound ( u ) for the binary systems (methanol + ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) were measured at 298.15, 303.15, 308.15 and 313.15 K and at atmospheric pressure in this work whereas the system (methanol + methyl acetate) was measured in the literature. The apparent molar volume, V φ , isentropic compressibility, k s , and apparent molar isentropic compressibility, k φ , have been calculated using density and speed of sound data, respectively. The limiting apparent molar volume, V φ 0 , and limiting apparent molar isentropic compressibility, k φ 0 , were found by extrapolation to infinite dilution using the Redlich–Mayer equation. The limiting apparent molar volume was used to obtain information about (solute–solvent) and (solute–solute) interactions. The temperature dependence of apparent molar volumes were used to calculate the apparent molar expansibility, E φ 0 , and Hepler's constant, ( ∂ 2 V φ 0 / ∂ T 2 ) P . The isobaric thermal expansion coefficient, α P , was also calculated. Positive k φ 0 values for all binary systems can be attributed to the predominance of solvent intrinsic compressibility over the solute intrinsic effect.

An influence of Al2O3 nanoparticles on the thermodynamic properties of isopropyl alcohol in the liquid phase has been studied. Experimental measurements of the two-phase specific heat capacity have been performed in the temperature range from 184 to 340 K for samples with the mass fractions of the nanoparticles 0.0201, 0.0511 and 0.0996 kg·kg-1. The method of monotonic heating in an adiabatic calorimeter of variable temperature has been applied. The saturated vapor pressure of the nanofluids has been measured at the temperatures from 297 to 352 K and concentrations of the nanoparticles in isopropyl alcohol 0.0253, 0.0444, 0.0687, 0.0955 kg·kg-1. The results obtained have shown that the specific isobaric heat capacity of the nanofluids decreases up to 8.6% at 0.0996 kg·kg-1 of Al2O3 nanoparticles in comparison with pure isopropyl alcohol. In addition, the influence of Al2O3 nanoparticles on the specific enthalpy and specific entropy of isopropyl alcohol in the liquid phase has been examined. It is established that both the specific heat capacity of the material of the nanoparticles and structural changes of the base fluid around the nanoparticles are main factors that determine a decrease of the specific isobaric heat capacity of isopropyl alcohol. It was shown that the excess molar volume and excess molar isobaric heat capacity are determined by properties of the interfacial phase of structurally oriented isopropyl alcohol molecules on the surface of nanoparticles. A new three-phase model for prediction the molar isobaric heat capacity of nanofluids is proposed. To predict caloric properties of nanofluids the proposed model requires only data for the molar volume of the investigated samples.

In this study, the solution and self aggregation properties of sodium dodecyl sulfate (SDS) in presence of synthesized small molecules i.e. 3-(2-chloro benzylideneamine))-2-(furan-2-yl) quinazoline-4(3H) one (Q1) and N-(2-(p-tolyl carbamoyl) phenyl) furan-2-carboxamide (Q2) has been determined. The two compounds were earlier screened for anticancer activity from NCI, USA. In order to investigate the physico-chemical properties, simple and controlled methods were employed to obtain critical micellar concentration (CMC) values and thermo-acoustic parameters via conductance, compressibility coefficient (β), apparent molar volume (ϕv) and apparent molar adiabatic compressibility (ϕk) of SDS in the presence of Q1/Q2 at different temperatures (25, 30, and 35 °C). In addition, the effect of the addition of Q1/Q2 in SDS solution and to gain information regarding interaction between the molecules, FTIR and 1H NMR spectroscopic analysis was also carried out. The presence of different substitutions on the molecules affecting SDS behavior has also been discussed.

Conductivities, densities and speeds of sound of 1-butyl-2,3-dimethylimidazolium chloride in aqueous solutions were measured at 15, 25, and 35 °C. These data have been used to characterize the aggregation process of imidazolium based ionic liquid in the aqueous solution. The critical aggregation concentration (cac) and the degree of ionization, α, were determined by conductivity measurements. Both quantities were used to calculate the standard free energy change of aggregation, Δ G a 0 . It shows decrease in α and Δ G a 0 upon growth of temperature. From density data for the ionic liquid, the apparent molar volume, Vϕ, was calculated. The adiabatic compressibility, βs, changes in adiabatic compressibility upon aggregation, Δ β s , agg , and apparent adiabatic compressibilities, βϕ,s, were calculated from measurements of density and ultrasound velocity. Good agreement has been found when comparing with the aggregation properties of 1-butyl-2,3-dimethylimidazolium chloride both from conductivity and molar volume approach.

The interactions of L -Alanyl- L -alanine (Ala-Ala), L -Alanyl- L -valine (Ala-Val), L -Alanyl- L -leucine (Ala-Leu) with drug ampicillin (AMP) as a function of temperature have been investigated by combination of volumetric and acoustic methods. Densities and speeds of sound of dipeptides of alanine in aqueous solutions of ampicillin have been measured at T = (305.15, 310.15 and 315.15) K and atmospheric pressure. The apparent molar volume (Vϕ), the partial molar volume (Vϕ0) and standard partial molar volumes of transfer (ΔVϕ0) for glycine and its dipeptides from water to aqueous ampicillin solutions have been calculated from density data. Partial molar adiabatic compressibility (κϕ,s) and partial molar adiabatic compressibility of transfer ( Δ κ ϕ , S 0 ) have been calculated from speed of sound data. The pair and triplet interaction coefficient have been calculated from both the properties. The results have been explained based on competing patterns of interactions of co-solvents and the solute.

Apparent molar volume ( ϕ V ), molar refraction ( R ), viscosity B -coefficient and adiabatic compressibility ( ϕ K ) of some bio-active solutes such as glycine, l -alanine, and l -valine have been measured in 0.01, 0.03, 0.05 mol dm −3 aqueous barium nitrate solutions at 298.15 K. Masson equation was employed for the limiting apparent molar volumes ( ϕ V 0 ) , experimental slopes ( S V * ) to interprete the solute–solvent and solute–solute interactions respectively. Molar refractions ( R ) have been calculated using the Lorentz–Lorenz equation. Jones–Dole equation was used to derive parameters A and B to interprete the interactions. Limiting apparent molar adiabatic compressibilities ( ϕ K 0 ) at infinite dilution were examined from the sound speed values.

The density (d) and speed of sound (u) for the binary systems were measured at 298.15, 303.15, 308.15, and 313.15 K under atmospheric pressure. The binary systems contained the ionic liquid (IL): methyltrioctylammoniumbis(trifluoromethylsulfonyl)imide ([MOA]+[Tf2N]−). The binary systems were ([MOA]+[Tf2N]− + ethyl acetate or ethanol). The apparent molar volume, Vφ, and the apparent molar isentropic compressibility, kφ, have been evaluated from the experimental density and speed of sound data, respectively. A Redlich–Mayer equation was fitted to the apparent molar volume and apparent molar isentropic compressibility data. The partial molar volume, V φ 0 , and partial molar isentropic compressibility, k φ 0 , of the binary mixtures have also been calculated at each temperature. The partial molar volume indicates that the intermolecular interactions for (IL + ethanol) are stronger than for (IL + ethyl acetate) at all temperatures and V φ 0 for both systems increases with an increase in temperature. The values of the infinite dilution apparent molar expansibility, E φ 0 , decreases with an increase in temperature. The isentropic compressibilities, ks, increases with an increase in temperature for both binary systems. Positive k φ 0 , for both binary systems can be attributed to the predominance of solvent intrinsic compressibility over the solute intrinsic effect.

In this work, densities data of binary liquid mixtures of ketones (2-butanone, 2-heptanone and cyclohexanone) with chloroalkanes (1,2-dichloroethane and 1,1,2,2-tetracloroethane) as a function of composition, under atmospheric pressure and at different temperatures from 288.15 to 313.15 K have been used to calculate excess molar volume. The partial volumetric properties at an infinite dilution were calculated using Redlich–Kister polynomial. We have also considered another approach, which is more convenient and accurate by calculating the partial volumetric properties at an infinite dilution through apparent molar volume.

The densities ρ and viscosities η of 1,2-ethanediol with 1,2-propanediol or 1,3-propanediol, and 1,2-propanediol with 1,3-propanediol binary liquid mixtures over the entire concentration range at temperatures (298.15 to 308.15) K with 5 K interval were measured. The experimental data were used to calculate the excess molar volume V m E , partial molar volume V ¯ m , i , partial molar volume at infinite dilution V ¯ i ∞ , apparent molar volume V φi , coefficient of thermal expansion α p , excess coefficient of thermal expansion α p E , excess viscosity η E , excess Gibbs energy of activation Δ G * E , and other thermodynamic parameters. A Redlich–Kister equation and Prigogine–Flory–Patterson (PFP) model was applied to correlate the excess molar volume results. Moreover, the viscosity data were correlated with the Grunberg–Nissan, Tamura–Kurata, Hind–Ubbelohde and Katti–Chaudhary equations. Good agreement was found between experimental data and modeling results.

In this work, we explore the anion effect on the thermophysical properties of protic ionic liquids (PILs) such as triethylammonium acetate [Et3NH][CH3COO] (TEAA), triethylammonium dihydrogen phosphate [Et3NH][H2PO4] (TEAP) and triethylammonium hydrogen sulfate [Et3NH][HSO4] (TEAS) with polar solvent such as dimethylsulfoxide (DMSO). To understand the molecular interactions between DMSO with ILs, densities (ρ), ultrasonic sound velocities (u) and viscosities (η) have been measured over whole range of compositions and at three temperatures, 298.15, 303.15, and 308.15 K under atmospheric pressure. A second order empirical polynomial and Arrhenius equations were used to correlate the ρ and η as function of temperature, respectively. Sound velocity mixing rules were used on experimental values. Further, the excess molar volume (VE), the deviation in isentropic compressibility (Δκs) and deviation in viscosity (Δη) were calculated using these properties. The obtained VE, Δκs and Δη values were correlated by using the Redlich–Kister polynomial equation.

The enthalpies of solution Δ sol H m have been determined for L-phenylalanine in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA). The measurements have been made at 298.15 K and mole fraction of amide x2 = (0–0.4) on the precise isothermic calorimeter. The results obtained have been used to calculate the standard enthalpies of solution ( Δ sol H ° ) and transfer ( Δ tr H ° ) of L-phenylalanine from water into mixtures as well as the enthalpy coefficients of pairwise interaction (hxy) of the solute with amide in aqueous media. The interrelation between enthalpy characteristics of dissolution (transfer) of L-phenylalanine and the composition of (water + amide) binary mixtures has been established. Contributions of the amides properties (molar volume, dipolarity/polarizability, acidity and basicity) to the energy of pairwise interactions have been estimated quantitatively by means of a modified Kamlet–Taft equation.

Dielectric constants (ɛ), densities (ρ), and refractive indices (nD) were measured for binary blend of tetramethylensulfone (TMS) or sulfolane and N-methyldiethanolamine (MDEA) at temperatures ranging from 293.15 to 328.15 K and atmospheric pressure over the whole mole fraction range. From these experimental data, the excess molar volume ( V m E ), and deviations in refractive indices (ΔnD), and relative permittivities (Δɛ), were calculated. These quantities were fitted to the Redlich–Kister polynomial equation to derive the binary adjustable parameters and standard errors. The effective dipole moment of pure liquid was calculated by using of Kirkwood–Frohlich equation.

The interactions of glycine (gly), glycylglycine (gly-gly), glycylleucine (gly-leu) with drug ampicillin as a function of temperature have been investigated by combination of volumetric and acoustic methods. Densities and speeds of sound of glycine and its dipeptides in aqueous solutions of ampicillin have been measured at T = (305.15, 310.15 and 315.15) K and atmospheric pressure. The apparent molar volume (Vϕ), the partial molar volume ( V ϕ 0 ) and standard partial molar volumes of transfer ( Δ V ϕ 0 ) for glycine and its dipeptides from water to aqueous ampicillin solutions have been calculated from density data. Partial molar adiabatic compressibility (Kϕ) and partial molar adiabatic compressibility of transfer ( Δ K ϕ 0 ) have been calculated from speed of sound data. The pair and triplet interaction coefficient have been calculated from both the properties. The absorption spectra have also been recorded for present mixtures with the help of UV–visible spectrophotometer. The results have been explained on the basis of competing patterns of interactions of co-solvents and the solute.

Electrolytic conductance ( Λ ), density ( ρ ), viscosity ( η ), refractive index ( n D ) and ultrasonic speed ( u ) of lithium halides LiX (where X = Cl, Br, I) have been studied in different mass fraction ( w 1 = 0.00–0.75) of acetonitrile (ACN) + 1,3-dioxolane (1,3-DO) mixtures at 298.15 K. The limiting molar conductivity ( Λ 0 ), association constant ( K A ), and distance of closest approach of ions ( R ) have been evaluated using Fuoss-conductance equation (1978). The deviation of conductometric curve ( Λ vs √ c ) from linearity in 1,3-DO, analyzed by the Fuoss–Kraus theory. The limiting apparent molar volume ( ϕ V 0 ), experimental slope ( S V * ) derived from Masson equation, and viscosity B and A -coefficients derived from Jones–Dole equation supplemented with density and viscosity data, respectively, have been interpreted in terms of ion–solvent and ion–ion interactions. The limiting partial molar adiabatic compressibility ( ϕ K 0 ), have also been obtained from the value of ultrasonic speed ( u ) and discussed them to interpret the same.

The ternary system of molten calcium chloride, potassium chloride and sodium chloride is an important electrolyte in the study of TiO2 electro-deoxidation methods. Therefore, the physicochemical data of the CaCl2–KCl–NaCl ternary system is very useful for optimizing of the electrochemical process. In this paper, the electrical conductivity, molar volume and density of molten CaCl2–KCl–NaCl system were predicted through a new generation geometric model. In order to evaluate the reliability of this method, the conductance of some composition points in the ternary system were also measured by electrochemical impedance spectroscopy (EIS) technique. The results show that the predictions of the model were agreed well with the experiment results. It is expected that this method can be used to solve the shortage of the physicochemical data for multicomponent molten systems.

Densities and speeds of sound of ( l -alanine + 1 mol L−1 aqueous glucose/1 mol L−1 aqueous sucrose) and ( l -threonine + 1 mol L−1 aqueous glucose/1 mol L−1aqueous sucrose) systems have been measured as a function of molal concentration of l -alanine and l -threonine at temperatures: (298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K. The partial molar volumes, transfer partial molar volumes, partial molar isentropic compressibilities and transfer partial molar isentropic compressibilities have been evaluated using the experimentally measured values of density and speed of sound. The trends of variations of experimental and computed parameters have been discussed in terms of ionic–hydrophilic, hydrophilic–hydrophilic and hydrophilic–hydrophobic interactions operative in the systems.

Densities, ρ, and viscosities, η, of pure 1-hexyl-3-methylimidazoliumtetrafluoro borate ([C6mim][BF4]) and 1-propanol, and their binary mixture {x1[C6mim][BF4] + x21-propanol} were measured at atmospheric pressure and in the temperature range of 293.15–333.15 K. The excess molar volumes, V m E , thermal expansion coefficients, α, and their excess values, αE, isothermal coefficient of excess molar enthalpy, ( ∂ H m E / ∂ p ) T , x and excess viscosities, ηE, were calculated from the experimental values of densities and viscosities. The excess molar volumes of the binary mixture are negative over the entire mole fraction range and increase with increasing temperature. Excess viscosities are negative over the entire mole fraction range of the mixture and decrease with increasing temperature. The obtained excess molar volumes and excess viscosities were correlated with the Redlich–Kister equation. The experimental results have also been used to examine the applicability of Prigogine–Flory–Patterson (PFP) theory in predicting the excess molar volume of the binary mixture. It is indicated that agreement between excess molar volumes calculated via PFP theory and the experimental results is good in all temperatures.

In this work, the linear isotherm regularity equation of state (LIR EoS) has been extended to predict the molar density of long chain primary and secondary amines, and esters and also the binary and ternary mixtures containing different functional groups. Each of these organic compounds has been assumed as a hypothetical mixture of methyl, methylene, and a functional group. Then, the LIR EoS has been modified for such a hypothetical mixture (MLIR EoS). Propane, n-butane, cyclohexane, 1-pentylamine, 2-aminobutane and n-butyl acetate have been used to investigate the contribution of the different segments in the new EoS parameters. The calculated parameters along with the MLIR EoS have been used to calculate the molar density and other thermodynamic properties of different pure compounds and their binary and ternary mixtures. A wide comparison has been made with some other EoSs and correlations. The results show that the MLIR EoS gives better results than other methods in accord with experimental data.

Densities, ρ and speeds of sound, u of tetrahydropyran (i) + pyridine or α -, β - or γ - picoline (j) binary mixtures at 298.15, 303.15 and 308.15 K and excess molar enthalpies, H E of the same set of mixtures at 308.15 K have been measured as a function of composition using an anton Parr vibrating-tube digital density and sound analyzer (model DSA 5000) and 2-drop micro-calorimeter, respectively. The resulting density and speed of sound data of the investigated mixtures have been utilized to predict excess molar volumes, V E and excess isentropic compressibilities, κ S E . The observed data have been analyzed in terms of (i) Graph theory; (ii) Prigogine–Flory–Patterson theory. It has been observed that V E , H E and κ S E data predicted by Graph theory compare well with their experimental values.

Densities ρ and speeds of sound u, of binary mixtures formed by 2-chloroaniline or 3-chloroaniline with diisopropyl ether or oxolane have been measured over the entire range of composition at a temperature of (303.15, 313.15 and 323.15 K) and atmospheric pressure. The ρ and u values were used to calculate isentropic compressibilities κS, Rao's molar sound functions R, intermolecular free lengths Lf, specific acoustic impedances Z, excess molar volumes V m E , excess isentropic compressibilities κ S E , excess intermolecular free lengths L f E and excess specific acoustic impedances ZE. The results have been used to investigate molecular interactions and structural effects in these mixtures. The speed of sound in present mixtures has been estimated using several empirical and theoretical models to determine their relative predicting ability in terms of pure component properties.

The Flory model has been applied to linear or cyclic ether + benzene, or +toluene mixtures. In addition, the relative variation of the molar excess enthalpy, H m E , along homologous series of the considered systems, has been discussed taking into account the contributions to H m E from the ether–ether, aromatic–aromatic and ether–aromatic interactions. It has been shown that in CH3(CH2)u−1O(CH2CH2O)v(CH2)u−1CH3 + benzene mixtures, the u increase (v fixed) leads to a weakening of interactions between unlike molecules, and that proximity effects also weaken this type of interactions. In contrast, the v increase (u fixed) or cyclization lead to stronger interactions between unlike molecules. From the application of the model, it is concluded that the random mixing hypothesis may be considered to be valid to a large extent for many of the investigated solutions. Erroneously, strong orientational effects are predicted for 1,3-dioxolane, or 1,4-dioxane + benzene systems, but this has been attributed to the model can not describe asymmetric H m E curves when the mixture compounds show close values for Vi (molar volume) and for V i * (reduction parameter for volume). Previous calculations on the basis of the Kirkwood–Buff integrals formalism confirm that the mixture structure is close to random mixing. Flory results on the excess molar volumes have been discussed taking into account the so-called curvature and P* contributions to this excess function.