Volumetric and Surface Properties of Short Chain Alcohols in Aqueous Solution–Air Systems at 293?K

From measurements of the surface tension, density, viscosity and light scattering of aqueous solutions of methanol, ethanol and propanol at 293?K, their activity in the surface monolayer, surface excess concentration, and apparent and partial molar volume were determined. The surface excess concentration of alcohols at the water?Cair interface was determined from the Gibbs equation by using both the alcohol's activity and their molar fraction in the bulk phase and recalculated by using the Guggenheim?CAdam equation. The values of the surface excess concentration determined from the Gibbs equation were also applied to determine the standard Gibbs energy of alcohol adsorption at the water?Cair interface from Langmuir??s equation and compared to those determined from that of Aronson and Rosen.     

醋酸离子液体[C2mim][OAc]水溶液的摩尔表面Gibbs自由能

在288.15-318.15 K温度范围内测定了不同浓度离子液体1-乙基-3-甲基咪唑醋酸盐([C₂mim][OAc])水溶液的表面张力和密度;在改进李以圭等人的溶液表面张力模型基础上,提出摩尔表面Gibbs自由能新概念,建立了摩尔表面Gibbs自由能随溶液浓度变化的线性经验方程,利用这个经验方程估算了[C₂mim][OAc]水溶液的摩尔表面Gibbs自由能,并进一步预测了该溶液的表面张力,其预测值与相应的表面张力实验值高度相关并非常相似。由此可见,摩尔表面Gibbs自由能与等张比容极其类似,可能成为预测离子液体及其溶液性质的一种新的半经验方法。在指定溶液浓度下,根据溶液的摩尔表面Gibbs自由能随温度呈线性变化的规律,得到了新的Eötvös方程,与传统的Eötvös方程相比,新Eötvös方程的每一个参数都有明确的物理意义:斜率的负值是摩尔表面熵,截距是摩尔表面焓,在指定浓度的溶液中摩尔表面焓几乎不随温度变化。     

Density,viscosity, and excess properties of aqueous solution of diethylenetriamine (DETA)

Densities and viscosities of aqueous DETA solutions were measured for the entire concentration range and for the temperature range between (293.15 and 363.15) K. The excess molar volume was determined from the experimental density data whereas the excess Gibbs free energy and the excess entropy of flow were determined from the experimental viscosity data by implementing the theory of rate processes of Eyring. A Redlich–Kister equation was applied to correlate the excess properties such as: the excess molar volume and the excess Gibbs free energy of flow as functions of the DETA mole fraction and temperature. The results showed that the model agree very well with the experimental data. In comparison with AEEA and DEA, the excess properties of DETA are higher than these amines.     

Densities and viscosities for binary mixtures of phenetole with 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol,and 1-decanol at different temperatures

Density (ρ) and viscosity (η) values of the binary mixtures of phenetole+1-pentanol, + 1-hexanol, + 1-heptanol, + 1-octanol, + 1-nonanol, and + 1-decanol over the entire range of mole fraction at 293.15, 298.15, 308.15, and 318.15 K have been measured at atmospheric pressure. The excess molar volume (V^E), viscosity deviations (Δη), and excess Gibbs energy of activation (G*^E) have been calculated from the experimental measurements. These results were fitted to Redlich and Kister polynomial equation to estimate the binary interaction parameters. The viscosity data were correlated with equations of Grunberg and Nissan, Hind et al., Frenkel, and McAllister. While the excess molar volumes of phenetole+1-pentanol, + 1-hexanol are positive, the remaining binary mixtures are negative. The viscosity deviations and excess Gibbs energy of activation are negative for all investigated systems. As the chain length of 1-alkanols increases, both viscosity deviations and excess molar volume values decrease while excess Gibbs energy of activation value increase. The temperature has no effect on excess molar volume, slight effect on excess Gibbs energy of activation, and significant effect on viscosity deviations. The calculated functions have been used to explain the intermolecular interaction between the mixing components.     

Interrelation between the physicochemical properties of MnCl2-MCl (M = Li, Na, K, Rb, and Cs) melts

Our own experimental studies of vapor pressure and surface tension were used to analyze isotherms of various types of the properties under consideration. The data obtained were processed using a mathematical model to calculate the molar surface and excess molar Gibbs energy, which clearly indicated that the surface properties obeyed the general rules that governed changes in these properties of solutions according to the position of alkali metals in the periodic table of the elements. The data on various physicochemical properties of the cesium chloride-manganese chloride system are evidence of the presence of singular extremum points on concentration dependence isotherms.     

Some Physical Properties of Binary Liquid Systems: (2-Butanone + n-Propionic Acid or n-Butyric Acid)

Abstract

Density, viscosity and surface tension of two binary liquid systems: 2-butanone + n-propionic acid, 2-butanone + n-butyric acid have been determined at 20, 30 and 40°C, over the whole compositional range. The excess values of molar volume, viscosity, Gibbs free energy for the activation of flow and surface tension were evaluated. These excess values were fitted to a Redlich-Kister type of equation. The Grunberg-Nissan parameter, d, was also calculated. The binary viscosity data were fitted to the models of McAllister, Heric, Auslander and Teja and Rice. Surface tension data were fitted to the models of Zihao and Jufu, Rice and Teja, and an empirical two-constant model proposed in this study.     

Surface adsorption and micelle formation of aqueous solutions of polyethyleneglycol and sugar surfactants

The surface tension of aqueous solutions of tetraethyleneglycol octyl ether (C8E4) and octyl-β-d-maltopyranoside (OM) mixture was measured as a function of the total molality of surfactants and the composition of OM under atmospheric pressure at 298.15 K by drop volume technique. The results of surface tension measurements were analyzed by originally developed thermodynamic equations, then phase diagrams of adsorption and micelle formation were constructed. From the analysis of the surface tension data, it was found that the C8E4 and OM molecules interact attractively in the adsorbed film and the excess Gibbs energy of adsorption can be compared with those observed in typical cationic–nonionic surfactant systems; nevertheless, they are mixed almost ideally in the mixed micelle. Judging from a negative excess surface area calculated by differentiating the excess Gibbs energy by the surface tension, we concluded that the attraction between C8E4 and OM molecules is a short-range one originated in the hydrogen bonding between them which favors the planar configuration.     

Excess partial molar enthalpies,entropies, Gibbs energies,and volumes in aqueous dimethylsulfoxide

The excess partial molar enthalpies, the vapor pressures, and the densities of dimethylsulfoxide (DMSO)–H₂O mixtures were measured and the excess partial molar Gibbs energies and the partial molar volumes were calculated for DMSO and for H₂O. The values of the excess partial molar Gibbs energies for both DMSO and H₂O are negative over the entire composition range. The results for the water-rich region indicated that the presence of DMSO enhances the hydrogen bond network of H₂O. Unlike monohydric alcohols, however, the solute-solute interaction is repulsive in terms of the Gibbs energy. This was a result of the fact that the repulsion among solutes in terms of enthalpy surpassed the attraction in terms of entropy. The data in the DMSO-rich region suggest that DMSO molecules form clusters which protect H₂O molecules from exposure to the nonpolar alkyl groups of DMSO.     

A principle to correlate extreme values of excess thermodynamic functions with partial molar quantities

Excess thermodynamic properties are widely used quantitatively for fluids. It was found that at constant temperature and pressure a molar excess quantity of a mutually miscible binary mixture at the extreme points equals the excess partial molar quantities of the two components, i.e.F ^E ₁=F ^E ₂=F ^E _m, forming a triple cross point. The relationship is hold for properties such as enthalpy, entropy, Gibbs free energy, and volume, and is applicable for excess functions with multi extreme points. Solutions at extreme points can be referred to as special mixtures. Particularly for a special mixture of Gibbs free energy, activity coefficients of the two components are identical.     

Viscosity,refractive index,and surface tension of multicomponent systems: Mathematical representation and estimation from data for binary systems

An equation previously developed for estimation of the excess thermodynamic properties of multicomponent systems from binary mixing data has been applied to other physical properties through extrathermodynamic properties such as the excess Gibbs free energy of activation for viscous flow, molar refractivity, and exess surface free energy. This equation provides reasonably accurate predictions for viscosity, refractive index and surface tension of ternary and quaternary systems, given the properties of the various binary combinations of the components. The equation also serves quite well as a point-of-departure for mathematical representation of experimental data, in that all of the data considered could be represented within experimental uncertainty with the aid of no more than one adjustable parameter for each multicomponent system.     

Volumetric and surface properties of pure ionic liquid n-octyl-pyridinium nitrate and its binary mixture with alcohol

The density and surface tension for pure ionic liquid N-octyl-pyridinium nitrate were measured from (293.15 to 328.15) K. The coefficient of thermal expansion, molecular volume, standard entropies, and lattice energy were calculated from the experimental density values. The critical temperature, surface entropy, surface enthalpy, and enthalpy of vaporization were also studied from the experimental surface tension results. Density and surface tension were also determined for binary mixtures of (N-octyl-pyridinium nitrate + alcohol) (methanol, ethanol, and 1-butanol) systems over the whole composition range at 298.15 K and atmospheric pressure. Excess molar volumes and surface tension deviations for the binary systems have been calculated and were fitted to a Redlich–Kister equation to determine the fitting parameters and the root mean square deviations. The partial molar volume, excess partial molar volume, and apparent molar volume of the component IL and alcohol in the binary mixtures were also discussed.     

Excess molar volumes,viscosity, refractive index,and Gibbs energy of activation of binary biodiesel + benzene,and biodiesel + toluene mixtures at 298.15 and 303.15 K

Excess molar volumes (V ^E), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at 298.15 and 303.15 K. The excess molar volumes V ^E were determined from density, while the excess Gibbs free energy of activation G*^E was calculated from viscosity deviation Δη. The excess molar volume (V ^E), viscosity deviation (Δη), and excess Gibbs energy of activation (G*^E) were fitted to the Redlich-Kister polynomial equation to derive binary coefficients and estimate the standard deviations between the experimental data and calculation results. All mixtures showed positive V ^E values obviously caused by increased physical interactions between biodiesel and the organic solvents.     

Synthesis and surface activity of novel glucose ester surfactants containing carbohydrate and hydrocarbon chain

A series of glucosyl esters surfactants were synthesized based on glucose molecule by enzymatic catalysis. It could reach the highest esterification yield of 83.4% at the optimal condition, molar ratio of D-glucose and fatty acyl amino acid as 3:2 using 11% (w/w) enzyme catalyst Lipozyme 435 as catalyst in t-butanol at 40°C. The surface activities were studied, such as the critical micelle concentration (CMC), surface tension (γ_cmc), maximum excess concentration (Γ_max), minimum surface area/molecule (A_min), and the adsorption efficiency (pC₂₀); values of these were obtained by surface tension test. The results show that the longer the hydrophobic chain length, the lower the CMC and γ_cmc. The CMCs of novel glucosyl esters were between 4.4 and 1.5 mM. Further, the micellization physiochemical parameters, including Gibbs free energy of micellization (ΔG), standard enthalpy change (ΔH), and standard entropy change (ΔS) were calculated. It was indicated the micellization of glucosyl esters 9–16 was driven by entropy and deduced at different temperature.     

Density, Viscosity, Velocity and Refractive Index of Binary Mixtures of Poly(Ethylene Glycol) 200 with Ethanolamine, m-Cresol and Aniline at 298.15 K

Densities, absolute viscosities, ultrasonic velocities and refractive indices of binary mixtures of poly(ethylene glycol) 200 with ethanolamine, m-cresol and aniline have been measured at 298.15 K, under atmospheric pressure, over the entire composition range. The experimental data have been used to calculate acoustic impedance, specific heat ratio and relative association for these binary mixtures. Excess molar volume, deviation in viscosity, deviation in refractive index, deviation in isentropic compressibility, excess acoustical impedance and excess Gibbs energy of activation for viscous flow have been plotted to determine the nature and extent of interaction present in the solutions. The results have been fitted to Redlich-Kister polynomial equation. The results have been explained in terms of specific intermolecular and intramolecular interactions present in the mixtures and are found to support each other. The isothermal compressibility for the binary mixtures was predicted by an equation based on Flory??s statistical theory and three rigid sphere equations.     

Effect of temperature on the density and surface tension of aqueous solutions of HMT

In this study, a systematic study of the effect of the temperature on the density and surface tension of HMT (hexamethylentetramine) in water was developed. The density and surface tension were determined at temperatures of 288.15, 293.15, 298.15, 303.15, and 308.15 K. Precise data of surface tension have not been reported previously in literature. From the density measurements, the apparent molar and partial molar volumes were calculated. The apparent molar volume decreases with concentration, the molar partial volume increases with temperature. The surface tension of the aqueous solutions of HMT decreases with concentration. The excess surface concentration was calculated, the values increase with concentration, indicating that the amount of HMT that goes to the interface gas liquid increases at higher concentrations of HMT.     

Effect of Organic Counterions on the Properties of N-Lauryl Diisopropanolamine Surfactants

The influence of counterions on the surface properties of N-lauryl diisopropanolamine surfactants is delineated using conductometry and surface tension measurements. Twelve types of organic counterions have been studied: C₁–C₁₂ monocarboxylic acids anions. The surface properties of the synthesized surfactants, including surface tension, critical micelle concentration (CMC), effectiveness (π_CMC), efficiency (pC₂₀), maximum surface excess (Γ_max), minimum surface area (A_min), Gibbs energy of micellization (ΔG_mic), and adsorption (ΔG_ad) processes in the aqueous. The biodegradability of the prepared surfactants was tested in river water using the die-away method. Petroleum-collecting and petroleum-dispersing capacities of the synthesized compounds on the surface of water of varying mineralization degree have been studied.     

The reduced Redlich–Kister excess molar Gibbs energy of activation of viscous flow and derived properties in 1,4-dioxane + water binary mixtures from 293.15 to 309.15 K

The excess molar volume, viscosity deviation and excess Gibbs free energy of activation of viscous flow have been investigated from the density and shear viscosity measurements of water–dioxane mixtures over the entire range of mole fractions from 293.15 to 309.15?K. The results were fitted by the Redlich–Kister equation. Partial molar volume and Gibbs energy at infinite dilution were deduced from four methods, activation parameters and partial molar Gibbs energy of activation of viscous flow against compositions were investigated. The water–dioxane interactions have principally an H-bound character and there are two principal types’ structures limited by 0.08?mole fraction in dioxane. The reduced Redlich–Kister excess properties provide an indication of the intermolecular interactions and for dioxane–water cluster formation as suggested in the literature.     

Composition of Surface Layer at the Water–Air Interface and Micelles of Triton X-100 + Rhamnolipid Mixtures

Measurements of the surface tensions, densities and viscosities of aqueous solutions of Triton X-100 (TX-100) and rhamnolipid (RL) mixtures, at constant concentration of RL or TX-100, were carried out. The measured values of the surface tension were compared to those determined using different theoretical models and on the basis of the surface tension of aqueous solutions of individual surfactants. From the surface tension isotherms, the Gibbs surface excess concentration of TX-100 and RL, the composition of surface layer and the standard Gibbs free energy of adsorption at the water–air interface were determined. Moreover, on the basis of surface tension, density and viscosity isotherms, the CMC of surfactants mixtures were evaluated. From the density isotherms, apparent and partial molar volumes of TX-100 and RL were also determined. These volumes were compared to those calculated from the sizes of TX-100 and RL molecules. There was observed a synergetic effect in the reduction of water surface tension and micelle formation, which was confirmed by the intermolecular interactions parameter. In the case of micelle formation, this effect was discussed based on the standard Gibbs free energy of micellization as well as of TX-100 and RL mixing in the micelles. The synergism of TX-100 and RL mixtures in the reduction of water surface tension and micelle formation was explained on the basis of electrostatic interactions between the hydrophilic part of TX-100 and RL molecules; this was supported by pH measurements.     

Properties of n-butylpyridinium nitrate ionic liquid and its binary mixtures with water

The density and surface tension of the pure ionic liquid n-butylpyridinium nitrate ([BuPy]NO₃) were determined at temperature range from T = (293.15 to 338.15) K. The coefficient of thermal expansion, molecular volume and lattice energy of [BuPy]NO₃ were calculated from the experimental values of density. The surface entropy and enthalpy of [BuPy]NO₃ were investigated. The IL studied show much lower surface enthalpy and lattice energy in comparison with fused salts. The densities and surface tensions of binary mixtures of [BuPy]NO₃ with water have been measured within the whole composition range at T = 298.15 K and atmospheric pressure. Excess molar volumes V^E and surface tension deviations δγ were then deduced from the experimental results as well as partial molar volumes and excess partial molar volumes. Excess molar volumes have a negative deviation from ideal behavior and the surface tension deviations are negative over the whole compositions range. V^E and δγ were correlated with suitable equation respectively.     

Excess thermodynamic properties for methyl isobutyl ketone + tert-amyl alcohol system at 25°C

The excess molar volume, excess viscosity, and excess molar enthalpy were calculated from the experimental density, viscosity, and heat of mixing, respectively, at 25°C for the methyl isobutyl ketone + tert-amyl alcohol system over the complete mole fraction range. The modified UNIFAC group contribution method was used to estimate the activity coefficients which in turn were used to estimate the excess molar Gibbs free energy. Molecular interactions in this mixture were obtained from the variation of the excess functions with composition.