Negative Excess Molar Volumes Research Articles

Elucidation of hydrogen bond strength of benzylalcohol with alkyl Acetoacetates: The confirmation study by excess thermodynamic Properties, FTIR and DFT analysis

In this study, density of pure liquids and their binary mixtures of benzylalcohol (BA) with methyl acetoacetate (MAA), ethyl acetoacetate (EAA) and allyl acetoacetate (AAA) were measured experimentally at T=(298.15–313.15) K and P = 0.1 MPa by using Rudolph Research Analytical digital densitometer. Experimental data was correlate by applying Jouyban–Acree theoretical equation. Furthermore, the speed of sound of all studied pure and their binary solutions were measured at T= (298.15 and 308.15) K at atmospheric pressure at 2 MHz. The experimental density and speed of sound data further were used to calculate the excess molar volume (VmE), isentropic compressibility (κs), excess isentropic compressibility (κsE) and excess speed of sound (uE) at all compositions and temperature ranges. The calculated VmE, κsE, uE and experimental speed of sound were compared with theoretical models such as Redlich-Kister, Hwang, CFT and FLT equations. The obtained data were analyzed in terms of intermolecular interactions such as hydrogen bond formation between two atoms of benzylalcohol and acetoacetates. Among all the three systems, BA + MAA showed highest negative excess molar volume magnitude due to the change of molecular geometry through the keto-enol tautomerism. The negative magnitude of VmE data confirms the formation of H-bond between the –OH---O- groups of component molecules. Similarly, BA + EAA system showed highest negative magnitude of κSE owing to the more compressible than resultant ideal solutions. The deviation in κSE magnitude in binary systems due to the geometrical fitting and specific interactions in atoms of the benzylalcohol and acetoacetates. Furthermore, the existence of hydrogen bond and its strength in binary mixtures were confirmed by experimental FTIR spectroscopy and theoretical density functional theory (DFT) calculations.

The excess volumes of protic ionic liquids and its significance to their thermodynamic modelling

With the increasing number of applications being reported for protic ionic liquids (PILs), there is a demand for the development of thermodynamic models that can accurately describe their thermophysical properties and phase equilibria, with equations of state (EoS) derived from the Statistical Associating Fluid Theory (SAFT) being amongst the best.This work aims at discussing the development of such models and the advantages of not using the pseudo-pure component approach commonly adopted in literature, but instead using an individual component approach as previously proposed for Deep Eutectic Systems (DES). Although both PILs and DESs are highly non-ideal mixtures of Brønsted or Lewis acids and bases, PILs are shown to exhibit large negative excess molar volumes when compared to DESs that prevent the direct prediction of the PIL properties by modelling it as a mixture of its precursors, using an individual component approach. To overcome this limitation, and to highlight the importance of being aware of such characteristic of the PILs when developing new models, a simplified volume-shift type correction is applied in the framework of PC-SAFT EoS to provide a more accurate modelling of PILs density data. The implemented correction is shown to increase the accuracy and predictive ability of the model, and its limitations are discussed, suggesting the need for additional experimental data (e.g., on the quantification of the different species present) for the development of robust and general thermodynamic models for PILs

Thermodynamics of mixtures with strong negative deviations from Raoult’s law. XVIII: Excess molar enthalpies for the (1-alkanol + cyclohexylamine) systems at 298.15 K and modelling

Excess molar enthalpies, HmE, have been measured using a Tian-Calvet microcalorimeter for the systems CH3(CH2)u-1OH (u = 1,2,3,4,7,10) + cyclohexylamine at 298.15 K and 0.1 MPa. The HmE values are large and negative, indicating the existence of strong interactions between unlike molecules, which is consistent with the also large and negative excess molar volumes, VmE of these solutions, previously measured by us. The contribution from the equation of state term to HmE has been evaluated for the 1-alkanol + cyclohexylamine, or + 1-hexylamine, or + aniline mixtures, and the corresponding excess molar internal energies at constant volumes, Um,VE, determined. It is shown that such contribution is particularly important for the methanol + aniline system, in such way that the excess functions HmE and Um,VE have different sign at x1 = 0.5. The DISQUAC and ERAS models have been applied to the cyclohexylamine systems, and the interaction parameters reported. DISQUAC improves ERAS results on HmE. The latter model describes correctly the VmE curves. The variation of HmE of CH3(CH2)u-1OH + cyclohexylamine, or + 1-hexylamine, or + aniline mixtures with u along a homologous series with a given amine, or with the amine in mixtures with a given 1-alkanol is discussed in terms of the different interactional contributions to HmE.

Experimental and theoretical excess molar properties of aqueous choline chloride based deep eutectic solvents

Deep eutectic solvents (DESs), an alternative to ionic liquids and conventional molecular organic solvents have attracted scientific attention because of their unique physico-chemical properties that can be tuned judiciously. These physico-chemical properties are altered if water, the most eco-friendly solvent is present as an impurity or as a cosolvent. The peculiar effect of water on the thermodynamic properties of DESs composed of choline chloride (CH) as an hydrogen bond acceptor (HBA) and ethylene glycol (EG), glycerol (GLY) and 1,4-butanediol (BD) as hydrogen bond donors (HBD) in the ratio of 1:2 are reported here. Densities of the aqueous solutions of CH:EG, CH:GLY and CH:BD were measured over the entire range of composition and temperature ranges from 293.15 K to 323.15 K at atmospheric pressure. Intermolecular interactions responsible for the negative excess molar volumes VmE for all the mixtures studied have been discussed. The non-ideal behavior of the studied mixtures have been evaluated through comparing the values of VmE with the Prigogine−Flory−Patterson (PFP) theory and extended real associated solution model (ERAS). These results will be further utilized in industrial processes as well as in the thermodynamic modeling of DES based systems.

Synthesis and Analysis of Ionic Liquid As Additive for Li-Ion Battery Electrolyte

Lithium ion batteries are promising power sources for various applications such as portable electronics and electrical vehicles, due to their high specific energy density and long cycle life. As one key component of lithium ion battery, the electrolyte should allow lithium ion transport but prevent electron conduction. One big challenge of lithium ion battery is that the high voltage and high current in the charge process can cause self-decomposition of the electrolyte, leading to combustion of the battery. In order to solve the combustion problem in the fast charge process, new electrolyte materials with high ionic conductivity and good chemical stability are urgently needed.Ionic liquid is usually organic salt consisting of anion and cation with low vapor pressure, high boiling point, high ionic conductivity, large specific heat capacity, and non-flammable characteristics. Ionic liquid is aqueous at or near the room temperature. The features of ionic liquid such as the high heat resistance and wide liquid temperature range make it a promising electrolyte material for lithium ion battery.This project aims at tailoring the suitable structure of ionic liquid as the additive for lithium ion battery. Our ionic liquid is a designed composition of anion of TFSI as SEI forming additive and imidazole based cation. A two-step process has been developed for synthesizing ionic liquid. The physical and chemical properties of the ionic liquid were measured to evaluate the feasibility of applying ionic liquid to lithium ion battery.Both the density and the viscosity of the ionic liquid are measured at different temperatures. The density was found to decrease linearly with temperature in both single and binary system. The determined negative excess molar volume of ethyl acetate and ionic liquid system is relative to the interaction between different molecules. The viscosity of the analyzed electrolyte solvent was found to decrease linearly with increasing temperature. Arrhenius-like law was found to be able to fit the measured data well. The fitting parameters were able to predict viscosity at different temperature.The conductivity of the whole electrolyte system and compatibility with the active materials will be tested and discussed in the next study.

Densities, viscosities and excess properties of binary liquid mixtures of methyl tert-butyl ether with methanol and diisopropyl ether from 308.15 to 318.15 K at 0.1 MPa

ABSTRACT Densities and viscosities of binary mixtures for methyl tert-butyl ether (MTBE) with methanol and diisopropyl ether (DIPE) have been measured at temperatures of 308.15, 313.15 and 318.15 K and at atmospheric pressure over the entire composition range. The measured densities and viscosities were fitted using Jouyban-Acree model where mean relative deviation (MRD) lesser than 0.02% are obtained for both predictions. The excess molar volumes and the viscosity deviations are calculated from measured densities and viscosities. Redlich-Kister equation is then used to correlate excess molar volumes and viscosity deviations where good fits have been achieved. Negative excess molar volume and viscosity deviation have been obtained for binary mixture MTBE + methanol at all investigated temperatures which indicating the presence of chemical and structural interactions. However, lack of specific interactions has been observed for binary mixture MTBE + DIPE based on positive excess molar volume and small negative values of viscosity deviation.

Density, Speed of Sound, and Dynamic Viscosity of 1-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide/1-Butyl-3-methylimidazolium Hexafluorophosphate and N-Methylaniline Binary Systems from T = 298.15 to 323.15 K at 0.1 MPa

Density, speed of sound, and viscosity values were measured for different binary mixture concentrations of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]) + N-methylaniline (NMA) and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][Pf6]) + NMA systems at temperatures from T = 298.15 to 323.15 K under atmospheric pressure. The excess values of molar volume, molar isentropic compressibility, intermolecular free length, and viscosity were calculated. The partial molar volumes and partial molar isentropic compressibilities at infinite dilutions were also estimated. The Redlich–Kister equation was utilized to evaluate coefficients and standard deviations. The mechanism of effective packing between [Bmim][NTf2]/[Bmim][Pf6] and NMA was represented by the negative excess molar volumes. In both the studied systems, the occurrence of strong chemical interactions was represented by the negative excess intermolecular free length values. The present work clearly showed that the simu...

Comments on “Study of thermodynamic properties of binary mixtures of propionitrile with dimethylsulfoxide (or diethylsulfoxide) at temperatures from (298.15 to 323.15) K”

The negative excess molar volumes reported by Ghazoyan and coworkers for binary propionitrile + dimethyl sulfoxide and propionitrile + diethyl sulfoxide are not thermodynamically consistent with the positive numerical values that the authors give for the partial molar excess volumes for the individual mixture components. Moreover, the authors' calculated partial molar volumes of the individual mixture components are not consistent with the molar volumes of the mixtures based on the experimental densities.

A combined experimental and theoretical study on the structures, interactions and volumetric properties of guanidinium-based ionic liquid mixtures

Mixtures of ionic liquids (ILs) have shown their potential in both physical and chemical processes, regarded as alternatives to common ILs. In this work, four guanidinium-based ILs, 2-ethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([TMG(C2)][C2OSO3]) and bis(trifluoromethylsulfonyl)imide ([TMG(C2)][NTf2]), and 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([TMG(C2)2][C2OSO3]) and bis(trifluoromethylsulfonyl)imide ([TMG(C2)2][NTf2]), are employed to investigate the structures, interactions and properties of four systems of IL-IL binary mixtures, including [TMG(C2)][C2OSO3]x[NTf2]1-x, [TMG(C2)]x[TMG(C2)2]1-x[C2OSO3], [TMG(C2)]x[TMG(C2)2]1-x[NTf2] and [TMG(C2)2][NTf2]x[C2OSO3]1-x. Combining experiments with theory, the relationships among H-bond interactions, structures and volumetric properties have been revealed. 1H NMR characterizations show the changes of H-bond interactions in the IL-IL mixtures in relation to composition, and DFT calculations reveal significant cation-anion interactions through the active hydrogen atom (N+-H) and the methyl groups in the cations with the anions in the manner of HO and HF. The ethyl group in the [C2OSO3]- anion hardly forms interactions with other components. The size effect of the calculated system has been evaluated for the IL-IL clusters with 2, 4 and 8 ions. Different structures due to variation of cationic and anionic species have remarkable influence on the volumetric properties of the IL-IL mixtures. Negative excess molar volume (VEm) is found in [TMG(C2)]x[TMG(C2)2]1-x[C2OSO3], and it is caused by the close packing of ions. Positive VEm values indicate that interaction loss occurs in the other three systems, where a linear arrangement or square packing of ions with low space utilization is found.

Comments on “measurement and relationships of density and viscosity of 1,2 propylene glycol + dimethyl sulfoxide mixtures and spectral insight”

The apparent molar volumes of both 1,2‑propylene glycol and dimethyl sulfoxide calculated by Yang and coworkers are incorrect, and not consistent with the calculated negative values for the excess molar volumes. In the case of negative excess molar volumes the apparent molar volumes of the mixture components must be less than the molar volumes of the neat mixture co-solvents. This is not the case with the apparent molar volumes given in the published paper.

Densities, Speeds of Sound, and Viscosities of Binary Mixtures of ann-Alkylcyclohexane (n-Propyl-,n-Pentyl-,n-Hexyl-,n-Heptyl,n-Octyl-,n-Nonyl-,n-Decyl-, andn-Dodecyl-) withn-Hexadecane

This work reports densities, speeds of sound, and viscosities of binary mixtures of n-alkylcyclohexanes (propyl- to dodecylcyclohexane) in n-hexadecane as a function of temperature. Isentropic bulk moduli for these mixtures were calculated from these speed of sound and density data. Mixture densities increased with increasing alkylcyclohexane concentration. As the alkyl-chain length on the alkylcyclohexane increased, the excess molar volume decreased, with n-propylcyclohexane and n-dodecylcyclohexane mixtures having positive and negative excess molar volumes, respectively. Molecular dynamics simulations accurately predict densities and isentropic bulk moduli of n-propylcyclohexane and n-dodecylcyclohexane mixtures, and suggest that the differences in excess molar volumes for different alkyl-chain lengths are related to changes in molecular packing. The speed of sound as a function of mole fraction was modeled using a second-order polynomial, and viscosities were modeled using the McAllister three-body equ...

Density, excess molar volume and some of their derived properties of the binary systems of methyl acetate with methyl derivatives of monoethanolamine between 293.15 and 313.15 K

Densities at five temperatures in the range 293.15–313.15 K were reported for the systems of methyl acetate + N-methylethanolamine and + N, N-dimethylethanolamine. Excess molar volumes, apparent molar volumes, partial molar volumes and partial volumes at infinite dilution were calculated from the measured density data. Excess molar volumes were calculated from the measurement results and correlated as a function of composition using the Redlich–Kister relation. The densities plotted with respect to mole fraction of alkanolamine were found to be formed maxima at equimolar position for methyl acetate + N-methylethanolamine and were observed linear decrement of density with increasing concentration of alkanolamine for methyl acetate + N, N-dimethylethanolamine system. The excess molar volume represented as a function of mole fraction of alkanolamines showed different behavior for methyl acetate + N-methylethanolamine and methyl acetate + N, N-dimethylethanolamine. The excess molar volumes changed sign from large positive over a wide range of composition to very small negative within a short compositional range for methyl acetate + N, N-dimethylethanolamine system. In contrary, the methyl acetate + N-methylethanolamine system at all temperatures showed the complete negative excess molar volumes over the entire range of composition with minima at equimolar position.

Liquid density, viscosity, surface tension, and spectroscopic investigation of 1,2-ethanediamine + 1,2-propanediol for CO2 capture

Liquid densities, viscosities, and surface tensions play significant roles in fluid flow and industrial applications for CO2 capture. These data of 1,2-ethanediamine (EDA)+1,2-propanediol (PPD) binary system were measured under atmospheric pressure at T=(293.15 to 318.15) K throughout the entire concentration range. According to the experimental viscosities and densities, the viscosity deviation and excess molar volume values were respectively calculated, and the Redlich-Kister equation was used to fit the coefficients and to evaluate the deviations. The system exhibited negative excess molar volume values with a minimum at x1≈0.54 at experimental temperatures, and a maximum was found at x1≈0.76 for viscosity deviation. The solubility of CO2 was measured at different flow rates, and the maximum solubility was about 0.57g CO2 per 1g EDA+PPD system at 250mL/min CO2 flow rate. Furthermore, the intermolecular interaction of PPD with EDA was systemically discussed according to FTIR, UV–Vis, 1H NMR, and fluorescence spectral results, surface tension, and electrical conductivity data, and it was expressed as the form of HO-CH2(CH3)CH2O-H·NH2CH2CH2N(H2).

The study of physico-chemical properties of binary systems consisting of N-Methylcyclohexylamine with 2-alkanols at T = (298.15–328.15) K

In this work, densities, ρ and refractive indices, nD of N-Methylcyclohexylamine+2-alkanols have been measured over the entire range of composition at four temperatures 298.15, 308.15, 318.15 and 328.15K and ambient pressure (81.5kPa), using Anton Paar DMA 4500 oscillating densimeter and Anton Paar Abbemat 500 automatic refractometer. From experimental data, excess molar volumes, VmE, partial molar volumes, V‾‾i, apparent molar volumes, Vϕi, thermal expansion coefficients, α, excess thermal expansion coefficients, αE, isothermal coefficients of excess molar enthalpy, (∂HmE/P)T,x, and refractive index deviations, ΔnD, have been calculated for binary systems consisting of N-Methylcyclohexylamine+2-alkanols (2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol and 2-octanol). The excess molar volumes, VmE, and refractive index deviations, ΔnD were correlated with the Redlich–Kister polynomial equation. The effect of temperature and chain length of alcohol on the excess molar volumes and refractive index deviations are discussed in terms of molecular interaction between unlike molecules. The excess molar volumes were negative and refractive index deviations were positive over the entire composition range and were plotted against the mole fraction of 2-alkanols over the entire composition range. Negative excess molar volumes and positive refractive index deviations indicate the strong hydrogen bonding between unlike molecules of mixtures. A comparative study has been made of the refractive indices obtained experimentally and those calculated by means of the Lorentz–Lorenz, Gladstone–Dale, Weiner and Arago–Biot relations.

Density of aqueous choline chloride-based ionic liquids analogues

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 (298.15–353.15K). 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.

Density, viscosity, and conductivity of choline chloride + ethylene glycol as a deep eutectic solvent and its binary mixtures with dimethyl sulfoxide

Density, dynamic viscosity, and electrical conductivity of binary mixtures of ethaline (choline chloride+ethylene glycol at molar ratio 1:2) as a deep eutectic solvent (DES) with dimethyl sulfoxide were measured under atmospheric pressure at temperatures, T, from (308.15 to 363.15)K covering the entire mixture range. The mixtures exhibited negative excess molar volumes, VE, with a minimum at ethaline mole fractions of ×1≈0.4…0.5 that became more pronounced with increasing temperature. A similar minimum was found for the excess viscosity, Δη, of the mixtures. However, in contrast to VE the minimum of Δη became more shallow with increasing T. As expected, the electrical conductivity of the mixtures increased monotonically with increasing ×1 and T. The temperature dependence of viscosity and conductivity is well described by the Vogel−Fulcher−Tamman (VFT) equation.

Thermophysical Characterization of the Mixtures of the Ionic Liquid 1-Ethyl-3-Methylimidazolium Acetate with 1-Propanol or 2-Propanol

A thermal and physical characterization of the binary mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) with 1-propanol or with 2-propanol was carried out. Thermogravimetric analyses confirmed that the stability of the ionic liquid is not reduced by the presence of the propanols. The density, viscosity, refractive index, and surface tension of the two binary systems were experimentally determined over the entire composition range, at atmospheric pressure, and from 288.15 to 348.15 K (for the system [C2mim][OAc] + 1-propanol) or to 338.15 K (for the system [C2mim][OAc] + 2-propanol). All properties were found to decrease with an increase in temperature and in the concentration of alcohol in the system. Negative excess molar volume, positive logarithm viscosity change of mixing, and mostly negative surface tension change of mixing were obtained from the experimental data for the isotherms investigated. An analysis of the trends of these property changes of mixing in systems [C2...

A study on Volumetric and Viscometric Properties for the Mixtures of DMF and Other Alcohols from Temperatures ranges 303.15K to 323.15K

Densities, p, and viscosities, ?, of four binary systems: N,N-dimethyl formamide (DMF) + 1-propanol, DMF + 2-propanol, DMF + butanol and DMF + 1-pentanol have been measured at five different temperatures ranging form 303.15K to 323.15K at an interval of 5K. Excess molar volumes were found to be negative over the entire concentration ranges. The negative excess molar volume decreases with the increase of chain length of alcohol, the magnitude follows the order DMF+ 1-propanol >, + 2-propanol >, +butanol >, + 1-pentanol. The change of viscosity has been found to be sensitive to the chain length of alcohols. Excess viscosities and Grunberg- Nissan interaction parameters have been found to be positive for DMF + 1-propanol and DMF + 2-propanol systems, and negative for other two systems DMF + butanol and DMF + 1-pentanol. The thermodynamic energy of activation; such as, positive ?G#E each also compatible with the observation.

High pressure density and solubility for the CO2 + 1-ethyl-3-methylimidazolium ethylsulfate system

The solubility and density of the CO2+1-ethyl-3-methylimidazolium ethylsulfate system were investigated. The carbon dioxide solubility in the IL was measured in the temperature range 273–413K, for pressure up to 5MPa and CO2 mole fractions ranging from 0.02 to 0.5 using the isochoric method, while the system density was carried out at temperatures ranging from 278.15K to 398.15K, pressures from 10MPa to 120MPa and 0.2, 0.4, 0.7 and 0.8 CO2 mole fractions. Similar to what was previously observed for phosphonate-based ILs, the ionic liquid high polarity leads to positive deviations from ideality resulting from unfavorable interactions with the CO2.The results from the density and solubility derived properties show that the system presents important negative excess molar volumes, over the whole range of compositions and temperatures, and a negative entropy of solvation that suggests an increase in ordering of the solvent molecules surrounding the solute. The observed negative excess molar volumes result from the large difference between the molecular volumes of the species involved, with the small carbon dioxide molecules occupying the empty spaces between the larger IL ions, supporting the notion that the carbon dioxide, upon dissolution, occupies essentially the bulk free volume since the IL does not significantly expand upon gas absorption. These results portray ionic liquids as a porous media, like a soft sponge, with a huge free volume in which large amounts of carbon dioxide are able to accommodate during the dissolution process.

Physical properties of phosphonium ionic liquid and its mixtures with dodecane and water

Addition of molecular solvents, dodecane and water, to the hydrophobic phosphonium ionic liquid (IL) tetradecyltrihexylphosphonium bis-(2,4,4-trimethylpentyl)phosphinate decreases its density and viscosity significantly. These changes have been studied in the temperature interval between 15 and 60°C and explained in terms of structural changes. Dependences of density and viscosity on the composition of binary and ternary systems are strongly nonlinear. Excess molar volumes and thermal expansion coefficients have been estimated for dry and water saturated solvents with IL. Strong H-bonding in water saturated solvents has been concluded from large negative excess molar volumes and strong temperature dependence of the density in water saturated solvents. VFT, Litovitz and Arrhenius models were tested for the correlation of temperature dependence of pure IL viscosity, showing that IL is a typical strong liquid. Deviations of the viscosity of the solvents to the ideal mixture viscosity based on the Eyring’s theory of absolute rates were evaluated. In dynamic light scattering measurements, two different types of aggregates have been identified in the dry and water saturated solvents, with the mean size above 300 and 2nm, respectively. High content of water of up to 8 molecules per ion pair of IL points to the existence of reverse micelles in the water containing solvents with hydrophobic IL.