Excess Thermodynamic Properties Research Articles

Insights into non-ideal behaviour of benzyl alcohol with (C2-C4) carboxylic acids through volumetric, ultrasonic and ATR-FTIR spectroscopic studies

ABSTRACT In the present work, experimental density (ρ) and speed of sound (u) data for the binary mixtures of benzyl alcohol with acetic acid, propionic acid, and n-butyric acid have been reported over the complete range of mole fraction at 298.15 K ≤ T ≤ 313.15 K. Excess volumes (VE ), excess isentropic compressibilities (κs E ), excess partial molar volumes (), and excess partial molar volumes at infinite dilution () have been computed from the experimental data. The excess thermodynamic properties are found to be negative over the entire range of composition at the investigated temperatures. The temperature dependence of the excess thermodynamic properties has been investigated. All the excess functions are correlated with the Redlich-Kister equation. Further, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra for the studied binary solutions have been recorded at the equimolar composition to evaluate the extent of cross-association between component molecules through intermolecular hydrogen bonding.

Excess thermodynamic properties and FTIR studies of binary of 1, 3-dichlorobenzene with alkyl acetates (C1–C5) at different temperatures

Abstract Densities (ρ) and speed of sound (u) have been reported for the binary mixtures containing 1, 3- dichlorobenzene (1, 3-DCB) with methyl acetate, ethyl acetate, propyl acetate, butyl acetate and pentyl acetate at four different temperatures (T = 303.15, 308.15, 313.15 and 318.15 K) and at atmospheric pressure. The experimental data of densities and speeds of sound has been further utilized to calculate excess molar volume ( V m E ) and excess isentropic compressibility ( κ S E ) the excess properties have been fitted to Redlich-Kister equation. Further, V m E results have also been discussed by using Prigogine–Flory–Patterson (PFP). The experimental speeds of sound data in the present investigated mixtures were compared with various theoretical models like collision factor theory (CFT) and free length theory (FLT) to check their relative merits of pure component properties. Moreover, the experimental excess functions were correlated in terms of FTIR spectral analysis.

Excess Thermodynamic Properties and Molecular Interactions in Binary Liquid Mixture of o-xylene and N-nonane

Experimentally measured data for viscosity and refractive index of (o-Xylene + n-Nonane) binary mixture are reported in this research paper for various compositions for three different temperatures at atmospheric pressure. Modified Ubbelholde viscometer and Abbe-3L Refractometer were used for experimental measurements. Deviation in molar refraction (ΔR) and deviation in viscosity (Δη) w.r.t composition have been calculated from the experimental data. ‘Grunberg and Nissan’ equation and Herric’s Correlation were used to correlate the viscosity data. Excess thermodynamic properties were fitted to Redlich-Kister equation. Coefficients and standard deviations, hence obtained are reported. Variation in Excess Thermodynamic properties for the mixture have been discussed in terms of intermolecular interactions.

Temperature and pressure dependence of the alpha relaxation in ortho-terphenyl.

Molecular dynamics (MD) simulations of ortho-terphenyl using an all-atom model with the optimized potentials for liquid simulations (OPLS) force field were performed both in the high temperature Arrhenian region and at lower temperatures that include the onset of the super-Arrhenian region. From the MD simulations, the internal energy of both the equilibrium liquid and crystal was determined from 300 K to 600 K and at pressures from 0.1 MPa to 1 GPa. The translational and rotational diffusivities were also determined at these temperatures and pressures for the equilibrium liquid. It is shown that within a small offset, the excess internal energy Ūx from the MD simulations is consistent with the experimentally determined excess internal energy reported earlier [Caruthers and Medvedev, Phys. Rev. Mater. 2, 055604, (2018)]. The MD mobility data {including extremely long-time 1 atm simulations from the study by Eastwood et al. [J. Phys. Chem. B 117, 12898, (2013)]} were combined with experimental data to form a unified dataset, where it was shown that in both the high temperature Arrhenian region and the lower temperature super-Arrhenian region, the mobility is a linear function of 1/Ūx(T,p), albeit with different proportionality constants. The transition between the Arrhenian and super-Arrhenian regions is relatively sharp at a critical internal energy Ūx α. The 1/Ūx(T,p) model is able to describe the mobility data over nearly 16 orders-of-magnitude. Other excess thermodynamic properties such as excess enthalpy and excess entropy (i.e., the Adam-Gibbs model) are unable to unify the pressure dependence of the mobility.

Molecular interactions in liquid mixtures containing o-cresol and 1-alkanols: Thermodynamics, FT-IR and computational studies

Abstract To investigate the nature and class of association forces between the pure liquids and their liquid mixtures, we have been analyzed with excess thermodynamic properties, spectroscopic and computational techniques. Although, the thermodynamic parameters such as excess volume (VE), isentropic compressibility (ks) and excess isentropic compressibility (ksE) have been calculated using the experimental data of density (ρ) and speeds of sound (u) of o-cresol with 1-alkanols (C3–C8) namely, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol at different temperatures from 25 to 40 °C with interval of 5 °C and at 0.1 MPa. The calculated excess and deviation functions have been fitted to the Redlich-Kister polynomial equation and the results have been analyzed in terms of molecular interactions and structural effects. However, the FT-IR data strongly supports the presence of intra- and inter molecular interactions between component molecules in the liquid mixtures through changing the stretching vibrational frequency of various functional groups of pure liquids. In addition, the hydrogen bonding features between o-cresol with different 1-alkanols were examined by using a molecular modeling program with the help of density functional theory (DFT - B3LYP), the optimized geometries, bond characteristics, natural bond orbital (NBO) and interaction energies of pure components and their complexes have been analyzed theoretically to recognize the nature and strength of interactions between o-cresol and 1-alkanols.

Effect of temperature, nature of anion and alkyl chain length on the volumetric and acoustic properties of ionic liquid [C4C1im][MeSO4] with alkyl nitriles

Densities (ρ) and speeds of sound (u) of 1-butyl-3-methylimidazolium methyl sulphate, [C4C1im][MeSO4] with acetonitrile (ACN), propionitrile (PCN) and n-butyronitrile (n-BCN) in the complete composition range at temperatures between 298.15 K and 313.15 K with 5 K intervals and atmospheric pressure is reported. Solute-solvent interactions have been evaluated in the mixtures of [C4C1im][MeSO4] with alkyl nitriles by calculating excess volumes (VE) and excess isentropic compressibilities (κsE). The VE and κsE values as a function of mole fraction are correlated using a Redlich-Kister type expression. The excess functions (VE and κsE) are found to be negative over the complete range of mole fraction for the investigated binary solutions. The studied excess properties are found to increase with the increase in the alkyl chain length of alkyl nitriles. The excess thermodynamic properties of the mixed solvents are discussed in relation to intermolecular interactions and structural effects existing between the component molecules. In addition, the effect of the nature of anion of ionic liquid and temperature on the excess thermodynamic properties has been investigated.

FT-IR Spectroscopic study of excess thermodynamic and transport properties of liquid mixtures of p-chloroacetophenone with alkoxyalkanols

ABSTRACT Densities, speeds of sound and viscosities were measured for the binary mixtures para-chloroacetophenone (PCAP) with 2-alkoxyethanols (2-methoxyethanol [2-MOE], 2-ethoxyethanol [2-EOE] and 2-butoxyethanol [2-BOE]) at T = (303.15–318.15) K. These experimental data have been used to calculate excess volume (VE ), excess isentropic compressibility (KsE ), deviation in viscosity (∆η) and excess Gibbs free energy of activation of viscous flow (G*E ). The excess parameters have been fitted to the Redlich–Kister equation and the results were analysed in terms of acid–base interactions, hydrogen bond interactions and dipole–dipole interactions between unlike molecules. Further, the FTIR spectra have been recorded at 298.15 K and found to be useful for understanding the presence of hydrogen bonding between oxygen atom of carbonyl group of p-chloroacetophenone and hydrogen atom of the –OH group of 2-alkoxyethanols molecules in the present liquid mixtures. A good agreement is obtained between excess quantities and spectroscopic data.

Excess thermodynamic properties of intermolecular interactions in binary liquid mixtures of furfural with alkyl acetates (C1-C5) at different temperatures

Abstract In this paper, we reported the densities (ρ) and speeds of sound (u) for the binary mixtures containing furfural (FA) and alkyl esters (methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), butyl acetate (BA) and amyl acetate (AA) at four temperatures (T = 303.15, 308.15, 313.15 and 318.15 K) and at atmospheric pressure. These experimental results have been further used to calculate excess molar volume ( V m E ) and excess molar isentropic compressibility ( K S E ), excess intermolecular free length ( L f E ) and excess acoustic impedance (uE) have also been calculated to support the experimental results. The excess properties have been fitted to Redlich-Kister equation. Further, theoretical results have also been discussed by using Prigogine–Flory–Patterson (PFP) theory, Intermolecular free length theory and collision frequency theory. From the interpretation of excess properties, the existence of specific interactions and interactions due to formation of hydrogen bonding between the unlike molecules has been revealed.

Exact Local Composition Model for Two-Dimensional Lattice Fluids

The knowledge on the deviation of local composition from bulk composition has been proven to be powerful for modeling the excess thermodynamic properties of liquid mixtures. However, the exact solution to the local compositions is available for a few cases, such as the one-dimensional (1D) lattice fluids and for certain two-dimensional (2D) lattice fluids (the Ising models). We discover that the long-range correlation in the fluid structure, which is not present in 1D but is important in 2D, is the main reason for the complication of getting the exact local compositions for general 2D lattice fluids. In this work, a general approach for calculating the local compositions in 2D lattice fluids is developed. We show that for any stripe-like 2D lattices, the long-range correlations can be avoided by transforming the system to a multicomponent 1D system. The local compositions of such a system can be determined by minimization of the free energy of the mixture. We found that the local compositions, energy, and...

Thermophysical and molecular modelling insights into glycerol + alcohol liquid mixtures

A combined experimental and theoretical study on the micro and macroscopic properties of liquid mixtures containing glycerol, as common component, and 2-butanol, 2,3-butanediol, 2-methyl-1-propanol, and benzyl alcohol is reported in this work. Thermophysical properties were measured over the whole compositions range in the 298.15 K–318.15 K temperature range and analyzed considering excess thermodynamic properties in terms of intermolecular forces. Quantum chemistry and molecular dynamics simulations were carried to analyze the properties of mixed systems in terms of the characteristics of hydrogen bonding, nanostructuring and molecular level effects. The reported results provide a multiscale approach to the study on hydrogen bonding in complex alcohol mixtures.

Thermodynamic properties for binary mixtures of 1-chlorohexane + some hydrocarbons at different temperatures and atmospheric pressure

The values of densities and speeds of sound for the binary mixtures of 1-chorohexane with two hydrocarbons, as toluene and tetradecane, were measured at several temperatures in the range of (298.15 to 318.15) K and atmospheric pressure. The obtained experimental data of the mixture were correlated by the Jouyban-Acree model. From the experimental data, the related excess and deviation quantities, namely the excess molar volumes, the partial molar volumes, the excess speeds of sound, the isentropic compressibilities, the excess isentropic compressibilities, the molar isentropic compressibilities and the excess molar isentropic compressibilities, were calculated and reported in this work. All these excess thermodynamic properties were correlated with the Redlich-Kister polynomial equation. The experimental results have been also used to test the applicability of the Prigogine-Flory-Patterson theory. Discussions concerning the experimental and calculated results in relation to the molecular interactions and structural effects between components of mixtures are presented.

The structure properties, defect stability and excess properties in Am-doped LnPO4 (Ln = La, Ce, Nd, Sm, Eu, Gd) monazites

Understanding how minor actinides affect the synroc stability is very important for waste management. After a careful review of literature, however, existing reports did not reach a satisfactory level on the effect of minor actinides on monazite structural properties. In this study, the electronic properties, structures, defect formation energies and excess properties of Am-doped LnPO4 (Ln = La, Ce, Nd, Sm, Eu, Gd) monazites were investigated by first principles calculations. The calculation results indicate that the inner shell Am-5f orbital can participate in chemical bonding with O-2p orbital in all considered monazites. By analyzing their structures, we find the lengths of Am–O bond in Ln-monazite from La to Gd are gradually shortened, resulting in the shrinkage of [AmO9] polyhedron along the lanthanides, which is different from the evolution of their lattice parameters. This shrinkage plays an important role in the Am defect stability. For instance, the calculated vacancy defect formation energy reveals that the Am has a stronger binding energy in Gd-monazite, making it more difficult to form a vacancy defect. Moreover, after analyzing the thermodynamic excess properties, we find that Am-doped NdPO4 monazite has the highest thermodynamic stability, and all the Ln1-xAmxPO4 solid solutions can remain phase stable above 285 K.

On the Regular Behavior of a Binary Mixture of Ionic Liquids.

Binary mixtures of the ionic liquids 1-ethyl-3-methylimidazolium dicyanamide and tributyl(methyl)ammonium dicyanamide, [C2C1im]x[N4441](1-x)[N(CN)2], are studied by means of their excess properties (enthalpy and volume), their viscosity, and their Raman spectra. The mixtures exhibit positive values of excess volume VE and excess enthalpy HE. The plot of the logarithm of viscosity as a function of composition is consistent with the finding HE > 0. The excess thermodynamic properties of the ionic liquid mixtures are compared with well-known results for binary mixtures of (high-temperature) molten salts. The asymmetry of the curve HE versus composition is reproduced by considering the volumetric fraction of the [C2C1im]x[N4441](1-x)[N(CN)2] mixtures according to basic results of the theory of regular solutions. The anion totally symmetric stretching mode νs(C≡N) was used to probe the local environment around the anion in a Raman spectroscopy investigation of the [C2C1im]x[N4441](1-x)[N(CN)2] mixtures as a function of the composition. The Raman band shape (peak frequency and bandwidth) of the νs(C≡N) mode changes as expected from the fluctuation of concentration around the probe oscillator according to models for vibrational spectroscopy of liquid mixtures. This thermodynamic and spectroscopic study leads to the classification of the [C2C1im]x[N4441](1-x)[N(CN)2] mixture as a regular solution. The application of the regular solution equation for HE to other ionic liquid binary mixtures is discussed.

Molecular interaction of hexylene glycol with toluene, aniline, chlorobenzene, nitrobenzene, benzaldehyde and N,N-dimethylaniline at 308.15 and 318.15 K

ABSTRACT Densities, viscosities and ultrasonic velocities of binary liquid mixtures of hexylene glycol (2-methyl-2,4-pentanediol) with toluene, aniline, chlorobenzene, nitrobenzene, benzaldehyde and N,N-dimethylaniline have been measured at 308.15 and 318.15 K. From these data, excess volume (VE ), deviation in isentropic compressibility (∆KS ), deviation in viscosity (∆η), intermolecular free length (∆Lf ), intermolecular free volume (∆Vf ) and deviation in acoustic impedance (∆Z) have been calculated. FT-IR studied for appropriate mixture to conform hydrogen bonding. Thermodynamic excess properties have been correlated with the Redlich and Kister type of polynomial equation to derive the coefficients and standard errors. Variations in the calculated excess quantities have been studied for mixtures of hexylene glycol with component liquids. Intermolecular interactions have been interpreted from the obtaining experimental results.

PEG hydration and conformation in aqueous solution: Hints to macromolecular crowding

The molecular structural dynamics of PEG in aqueous solution has been addressed with a series of experimental data correlating macroscopic solution properties of PEG with structural and hydration properties at molecular level, by using thermodynamic, UV Brillouin and Raman spectroscopy data. Water activity measured in PEG 600 solutions by a novel dynamical calorimetry approach shows that data reveal some non-equilibrium process for dilute solutions. Brillouin scattering data on aqueous solutions in the UV range made possible the measurement of the viscoelastic relaxation of the system with a characteristic temperature, TM, as precursor of the glass transition process at lower T, while at constant temperature, the addition of water to liquid PEG 600 first lead to a slight decrease and then to an increase in the solution viscoelastic relaxation consistent with the slowest polymer dynamics observed in the concentrated solution. Specific Raman bands corresponding to trans and gauche conformations of the C–C and C–O bonds and their sequences in the PEG chain have been identified and their relative intensities as a function of concentration evidence non-monotonous variations with a rather unusual concentration dependence for the frequency of C–O bonds in the range of physiological temperatures.The heuristic result is that the extended time-space domains approach suggests an overall quasi-regular solution behavior of semidilute PEG, with opposite concentration dependence at low and at high water content, similar to discontinuities observed in excess thermodynamic properties and eutectic phase diagram. The cross-over of these distinct behaviors occurs at the concentration close to that usually employed to mimic the cellular crowding in biomolecular systems, highlighting the interplay of water molecules in solute-solute interactions.

Effects of Polygonum cuspidatum on expression of IL-6, IL-2 and AMPK in synovial membrane of collagen induced arthritis rats

To investigate the nature and class of association forces between the pure liquids and their liquid mixtures, we have been analyzed with excess thermodynamic properties, spectroscopic and computational techniques. Although, the thermodynamic parameters such as excess volume (VE), isentropic compressibility (ks) and excess isentropic compressibility (ksE) have been calculated using the experimental data of density (ρ) and speeds of sound (u) of o-cresol with 1-alkanols (C3–C8) namely, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol at different temperatures from 25 to 40 °C with interval of 5 °C and at 0.1 MPa. The calculated excess and deviation functions have been fitted to the Redlich-Kister polynomial equation and the results have been analyzed in terms of molecular interactions and structural effects. However, the FT-IR data strongly supports the presence of intra- and inter molecular interactions between component molecules in the liquid mixtures through changing the stretching vibrational frequency of various functional groups of pure liquids. In addition, the hydrogen bonding features between o-cresol with different 1-alkanols were examined by using a molecular modeling program with the help of density functional theory (DFT - B3LYP), the optimized geometries, bond characteristics, natural bond orbital (NBO) and interaction energies of pure components and their complexes have been analyzed theoretically to recognize the nature and strength of interactions between o-cresol and 1-alkanols.

Excess Molar Volume Calculation and Viscosity Deviation and Excess Gibbs Energy for Binary Solution of 1- Propanol with Butyl Acetate at Temperatures (40,50,60) 0C

In this research, the solubility Process of the binary liquid solution(1-Propanol and butyl acetate) were studied at temperature(40,50.60)0C. Densities ρ by pycnometer method and viscosity ƞ by OSTWALD tube that calibrated with distilled water was measured. Then excess molar volume was calculated of pure component and its mixtures that was prepared over the entire mole fraction range. It has been observed that excess molar volumes values were negative at all temperatures. After that, the deviation in viscosity ∆ ƞ and Excess Gibbs free energy ∆GE was determined and it has been observed that it takes negative values at all temperatures. Excess molar volume, deviation in viscosity, excess Gibbs free energy were correlated with Redlich-Kister equation Type polynomial and the showed an accepted standard deviation between the experimental and calculated values it has been shown the effect of Hydrogen bonds formation and the spherical shape for the molecules and its size on the excess thermodynamic properties.

Experimental thermodynamic investigation of the liquid Cu-Li-Sn system by Knudsen Effusion Mass Spectrometry

The thermodynamic activity of lithium was measured by Knudsen Effusion Mass Spectrometry (KEMS) within the Cu-Li-Sn system in the liquid region. For this purpose, eleven samples were studied between 773 and 1078 K in the Sn-rich part of the Cu-Li-Sn phase diagram. Mixing enthalpies, entropies and Gibbs energies were derived directly from the measured thermodynamic activity. The measured thermodynamic activities of Li were fitted to the Redlich-Kister-Muggianu (RKM) sub-regular solution model, by taking ternary interactions into account, using a mathematical regression procedure. Thereby, the partial and integral excess thermodynamic properties, the activities of Li, Cu and Sn and the ternary interaction L-parameters, as a function of temperature, were obtained.

The structuring in mixtures with acetone as the common solvent

ABSTRACTA molecular dynamics study of binary mixtures with acetone and different non-polar solutes (benzene, pentane and carbon tetrachloride) was undertaken. Through the analysis of different structural features, Kirkwood–Buff integrals, as well as energy distributions the weak nonideality is observed, governed mainly by the acetone’s interactions. The excess thermodynamic properties highlighted that the subtle balance between unfavourable energetic and favourable entropic contributions promotes mixing. The solutes, despite showing differences, exhibit globally similar behaviour. The characteristics of these mixtures contrast those of the acetone-methanol mixtures, which exhibit more complex structuring, dictated primarily by the methanol molecules.

Study of excess thermodynamic properties of binary systems containing cinnamaldehyde with alcohols supported by ATR-FTIR spectral studies

Abstract The thermophysical behavior of the binary mixtures trans-cinnamaldehyde (CA) with alcohols namely, methanol (MO), ethanol (EO), propanol (PO), isopropanol (IPO) has been studied through the measurement of density (ρ), speed of sound (u), over the entire mole fraction range at T = (298.15, 303.15, 308.15, 313.15) K under atmospheric pressure. Excess volume (VE) and excess isentropic compressibilities ( κ S E ) were also calculated and correlated with Redlich–Kister equation. Except for CA with MO and EO, the remaining investigated systems exhibit positive values of VE and all the four systems exhibit negative κ S E values over the entire composition range. Moreover, all the systems behave differently when the temperature is raised. Besides, ATR-FTIR spectroscopy is used for finding molecular interactions in component molecules.