Surface Tension Of Mixture Research Articles

Study of Density, Surface Tension, and Refractive Index of Binary Mixtures Containing Alkyl Levulinate and n-Alcohol from 298.15 to 323.15 K

Alkyl levulinate, prepared from the esterification of levulinic acid and n-alcohol, has the potential to be used as a fuel additive. Alcohol has also been used as an additive in fuel to improve ignition and combustion characteristics to a certain extent. For this reason, the properties of mixtures containing these compounds are of particular interest. Herein, measurements of density (ρ), surface tension (γ), and refractive index (n) were conducted for three binary mixtures of methyl levulinate–methanol (ML–M), ethyl levulinate–ethanol (EL–E), and n-butyl levulinate–butanol (BL–B). These properties were measured over the entire range of compositions in 0.1 increments of the molar fraction of the components in the temperature range of T = 298.15–323.15 K and at an atmospheric pressure of p = 0.1 MPa. The experimental data were used to calculate the excess and deviation properties, that is, excess molar volumes (VmΕ), surface tension deviations (Δγ), and molar refraction deviations (ΔR). The VmΕ, Δγ, and ΔR values were fitted to the Redlich–Kister polynomial equation. The VmΕ and ΔR values were negative for all compositions, whereas Δγ exhibited both negative and positive values at different compositions. The molecular interactions of the binary mixtures are discussed from these excess and deviation functions. Furthermore, the Jouyban–Acree model was used for the correlation of properties: density, surface tension, and refractive index of the studied mixtures at different temperatures (T = 298.15–323.15 K). The results are expected to provide fundamental data for understanding the properties of alkyl levulinate as a potential bio-based fuel additive.

SGTPy: A Python Code for Calculating the Interfacial Properties of Fluids Based on the Square Gradient Theory Using the SAFT-VR Mie Equation of State.

In this work, we showcase SGTPy, a Python open-source code developed to calculate interfacial properties (interfacial concentration profiles and interfacial or surface tension) for pure fluids and fluid mixtures. SGTPy employs the Square Gradient Theory (SGT) coupled to the Statistical Associating Fluid Theory of Variable Range employing a Mie potential (SAFT-VR-Mie). SGTPy uses standard Python numerical packages (i.e., NumPy, SciPy) and can be used under Jupyter notebooks. Its features are the calculation of phase stability, phase equilibria, interfacial properties, and the optimization of the SGT and SAFT parameters for vapor-liquid, liquid-liquid and vapor-liquid-liquid equilibria for pure fluids and multicomponent mixtures. Phase equilibrium calculations include two-phase and multiphase flash, bubble and dew points, and the tangent plane distance. For the computation of interfacial properties, SGTPy incorporates several options to solve the interfacial concentration, such as the path technique, an auxiliary time function, and orthogonal collocation. Additionally, the SGTPy code allows the inclusion of subroutines from other languages (e.g., Fortran, and C++) through Cython and f2py Python tools, which opens the possibility for future extensions or recycling tested and optimized subroutines from other codes. Supporting Information includes a review of the theoretical expressions required to couple SAFT-VR-Mie equation of state with the SGT. The use and capabilities of SGTPy are illustrated through step by step examples written on Jupyter notebooks for the cases of pure fluids and binary and ternary mixtures in bi- and three- phasic equilibria. The SGTPy code can be downloaded from https://github.com/gustavochm/SGTPy.

Surface tension of liquid mixtures and metal alloys. Thermodynamic conditions for the occurrence of a positive temperature coefficient

The atypical increase of surface tension when the temperature of a liquid alloy increases, is addressed using Butler’s thermodynamic model for an ideal surface phase. A rigorous expression for this temperature coefficient at fixed bulk alloy composition, requiring only pure-metal density and surface tension data and no arbitrary simplifying assumptions, is worked out. This theoretical development predicts the occurrence of positive temperature coefficients whenever a combination involving large difference of pure-metal surface tensions, temperatures close to the alloy melting point and molar surface area of the surface-active metal larger than that of the other component, is met. The proposed method is applied to the alloys Cu–Sn, Cu–In, Ag–Bi, Ag–Pb and Ag–Sn for which experimentally measured positive temperature coefficients have been reported. An acceptable agreement between theoretical and experimental values is documented. This theoretical approach predicts a negative temperature coefficient of the surface tension at fixed surface-phase composition, which is in fact the typical behaviour for this dependence. It is concluded that the temperature and composition ranges over which a certain binary alloy may exhibit positive temperature coefficient of the surface tension can be established beforehand using the proposed methodology.

A simple correlation to predict surface tension of binary mixtures containing ionic liquids

Ionic liquids are in a developing situation in nowadays research and industrial atmosphere. In some industrial applications and academic researches, one will face with binary mixtures containing ionic liquids, therefore; many studies have been done evaluating the properties of binary mixtures containing ionic liquids. In this study, it has been tried to find a general trend and precise correlation to predict surface tension of binary mixtures containing ionic liquids. To do this, Multi-Gene Genetic Programming (MGGP), which is one of the most powerful techniques of soft computing, has been used. Mole fraction, Temperature, Molecular weight of two components and boiling point have been used as input parameters of the network, where surface tension of the mixture was the output parameter. Utilizing the mentioned parameters and MGGP, precise networks obtained. On top of that, using MGGP, a general correlation has been generated for obtaining surface tension of binary mixtures containing Ionic Liquids variable with just mole fraction and in constant temperature. Moreover, adding one term to the mentioned correlation gave a precise correlation for the surface tension variable with mole fraction and temperature. These two correlations are very promising and simplifying for determining the surface tension of binary mixtures containing ionic liquids. The precision of these correlations has been evaluated using correlation coefficient (R2) and AARD, which was respectively, average 0.994 and 0.9567% for all used binary mixtures.

Surface tension of mixtures containing ionic liquids based on an equation of state and on the geometric similitude concept

A model based on a cubic equation of state and on the geometric similitude concept is proposed to calculate the surface tension of pure substances and mixtures containing organic substances, water, and ionic liquids. The geometric similitude is observed between surface tension and density for liquid mixtures at different temperatures and concentrations. The parameters of the model have been estimated by fitting experimental pure component data obtained from the literature. The model has been extended to binary and ternary mixtures using simple mixing and combining mixing rules without interaction parameters, so the predictive capabilities of the model are guaranteed. Data for 90 binary mixtures (2660 data) and 12 ternary mixtures (467 data) are considered. The mixtures are composed of organic solvent + ionic liquid and water + ionic liquids. The temperature varies from 278.15 to 348.15 K in the whole composition range at atmospheric pressure. Various form of estimating the necessary pure component parameters are analyzed. Results show that the model is accurate for primary estimation in process design and process simulation.

Surface tension of binary organic mixtures based on a new dimensionless number

Surface tension of various binary mixtures has been evaluated over the past years since the results add great contribution to many engineering applications. The binary systems {nonane + toluene, nonane + benzene, nonane + cyclooctane, hexadecane + toluene, hexadecane + benzene, hexadecane + cyclooctane} were studied since no literature data were conveyed based on our best review. Therefore, surface tension (σ) and density (ρ) of these binary systems were appraised at different temperatures of 298.2 K, 303.2 K, 308.2 K and 313.2 K at atmospheric pressure, and various mole fractions. Du Nouy Ring Device was applied experimentally to determine the surface tension of these organic mixtures. The outcomes were analyzed with the existing theoretical values attained from Brock-Bird correlation and Goldsack-Sarvas method and the average absolute relative deviations (AAD %) were obtained as 10.26% and 3.75%, respectively. In this work we have shown the success of our recent proposed model for correlating the surface tension of the studied binary organic mixtures with an overall average absolute relative deviation of 3.00%.

Surface tension as a function of temperature and composition for a broad range of mixtures

It is desirable to predict the surface tension of liquid mixtures for a wide range of compositions, temperatures, and pressures, but current state-of-the-art calculations (e.g., density gradient theory) are computationally expensive. We propose a computationally simple—but accurate—semi-empirical mathematical model of surface tension for a wide variety of multicomponent mixtures, including those with a supercritical compound when coupled with an equation of state (by introducing a reduced mole fraction scaled by a critical composition). Our predictions for binary systems with one supercritical component are an average of 0.22 mN/m away from literature experimental data (466 data points), and those for systems with two subcritical components (293–333 K) are within 0.09 mN/m (236 data points). We make predictions for methanol + ethanol + water using binary coefficients within an average of 0.71 mN/m (196 data points). Given its computational simplicity and wide applicability, the proposed model will be useful for many applications.

Investigation on the Surface Tension and Viscosity of (dimethylsulfoxide + alcohol) Mixtures by Using Gradient Theory and Eyring’s Rate Theory

The present study has been dedicated to modeling the surface tension and viscosity of (dimethylsulfoxide + alcohol) mixtures. The self and cross-association have been considered for both alcohol and dimethylsulfoxide, and the Cubic-Plus-Association equation of state is applied to the phase equilibrium calculations. The binary interaction parameters are obtained according to the experimental phase equilibrium data, taking advantage of accurate description of the phase equilibrium. Then the gradient theory is used to describe the surface tension and interface of (dimethylsulfoxide + alcohol) mixtures. Moreover, the Eyring’s rate theory is used to model the viscosity of (dimethylsulfoxide + alcohol) binary system. For more accurate description of the viscosity, an adjustable parameter of the Eyring’s rate theory is fitted based on the experimental viscosity data. The results of this investigation show that the application of association performs well for modeling the surface tension and viscosity of (dimethylsulfoxide + alcohol) mixtures.

Surface Tension and Viscosity of Binary Mixtures of the Fluorinated and Non-fluorinated Ionic Liquids [PFBMIm][PF6] and [C4C1Im][PF6] by the Pendant Drop Method and Surface Light Scattering

Mixtures of fluorinated and non-fluorinated ionic liquids (ILs) show a distinct structural organization in the bulk and at the surface. To understand how such microscopic effects influence the macroscopic bulk and surface properties of IL mixtures, knowledge of corresponding thermophysical properties including viscosity and surface tension is required yet lacking. With the intention of investigating surface enrichment effects of the fluorinated IL [PFBMIm][PF6] (3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate) in mixtures with the structurally similar, non-fluorinated IL [C4C1Im][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate) observed with angle-resolved X-ray photoelectron spectroscopy (ARXPS), the pendant drop method and surface light scattering (SLS) were applied in the present study to determine surface tension and dynamic viscosity between (293 and 368) K. By adding small amounts of [PFBMIm][PF6] up to 9 mol %, a distinct increase in the viscosity and decrease in the surface tension of the mixtures relative to the properties of pure [C4C1Im][PF6] was found. This behavior reflects the nanosegregated structure in the bulk and at the surface of the binary IL mixtures. Using the results about the pronounced surface enrichment of the fluorinated chain of [PFBMIm][PF6] quantified by ARXPS, a linear mixing rule for the surface tension of the IL mixtures based on the surface tensions of the pure ILs and the surface concentration of their most surface-active groups is suggested.

Surface Tension/Contact Angle Characters of Aprotic Binary Borneol-Dimethyl Sulphoxide Mixture

Borneol and dimethyl sulphoxide (DMSO) have been used as the skin penetration enhancers. Different concentrated borneol solutions in aprotic DMSO were prepared as the binary mixtures and determined their surface tension and contact angle behaviors using goniometer. Low borneol concentration minimized the surface tension and there was nearly stable contact angle for 30-70% borneol solutions. The trend contact angle value was decreased on glass slide, acrylic and LDPE whereas increasing on agarose gel and porcine tissues including buccal mucosa, gum and tongue with borneol concentration dependence. However, the borneol-DMSO binary mixture exhibited high wettability owing to its contact angle on glass surface was less than 90°. The solvent exchange between DMSO of borneol solutions and aqueous phase form agarose gel and porcine tissues including tongue, gum and buccal mucosa initiated the phase transformation from solution into matrix-like and promoted the higher contact angle with borneol concentration dependence. The understanding of surface tension and contact angle behaviors of aprotic borneol-DMSO binary mixture is useful for developing them into in situ forming gel for drug delivery such as in the oral cavity.

Density and surface tension of binary mixture of 1-nonanol +n-octane, +n-nonane, and +n-decane from (293.15 to 323.15) K at P = 0.1 MPa

We present the density and surface tension of binary mixtures n-octane, n-nonane and n-decane with 1-nonanol in the entire composition range at atmospheric pressure. The surface tension is measured from 293.15 K to 313.15 K while the density is measured from 293.15 to 323.15 K. Densities are obtained from a vibrating tube densimeter and surface tensions are from a drop volume tensiometer. Excess molar volumes and surface tension deviations are calculated from the experimental measurements and they are represented using Redlich-Kister type equations. Surface entropy and enthalpy are calculated using the temperature dependence of the surface tension.

Ultrasmall Polymer Nanoparticles Formed by Instantaneous Nanosplitting of Surfactant-Free Emulsion.

Application of polymer nanoparticles has progressively broadened. There is now increasing interest in smaller polymer nanoparticles for use in organic solar cells and drug delivery systems. Unfortunately, it is difficult to control the particle size below 50 nm with conventional synthesis methods. Our previously proposed "two-step nanoprecipitation method" overcomes this problem. An oil-in-water emulsion is first formed from polymer solution and deionized water without using surfactant; it is then injected into ethanol to form particles. The particle formation mechanism in this method has now been investigated, and an interesting phenomenon was discovered: the injected droplets instantaneously split into nanosize droplets with a size of 100-150 nm. The splitting was very effective, and the formed nanosize droplets were virtually monodisperse. This occurred only for a mixture composition in which the surface tension of the poor solvent mixture (water and ethanol) equaled that of the good solvent. This composition also resulted in formation of the smallest particles. By adjusting the conditions, we were able to synthesize extremely small nanoparticles (∼5 nm) of poly(3-hexylthiophene). This method has the potential to synthesize nanoparticles composed of other types of materials, such as nonconductive polymers and small molecules.

Concentration dependence of the sol-gel phase behavior of agarose-water system observed by the optical bubble pressure tensiometry

We have studied an expansion behavior of pressurized bubbles at the orifice of a capillary inserted in gelator-solvent (agarose-water) mixtures as a function of the gelator concentration in which the phase transition points are included. The pressure (P) -dependence of the radius of the curvature (R) of the bubbles monitored by laser beam has shown a discontinuous decrease in the exponent (m) of the experimental power law R = KΔP−m (K: constant) from 1 to 1/2 and a discontinuous increase in the average surface tension (γave) obtained from the work-area plots of the mixtures exceeding that of pure water (72.6 mN/m) at 0.02 < [agarose] < 0.03 wt%, which is attributed to the disappearance of the fluidity. The apparent surface tension (γapp = ΔP/2 R) of the system in the concentration range of 0.03–0.20 wt% has been analyzed by a modified Shuttleworth equation γapp = σ0 + τln(A/A0), where σ0 is an isotropic constant component and the second term is a surface area (A) -dependent elastic component, in which τ is the coefficient and A0 is the area of the orifice. The analysis has indicated that σ0 coincides with the γapp value of the mixture of 0.02 wt% and the second term at >0.02 wt% is the dominant component. From the appearance of the elastic component and concentration dependence of τ, the plateau of τ for the agarose-water mixtures at 0.03–0.10 wt% (Region II) has been explained to the phase separation giving two-phase mixtures of 0.02 wt% sol and 0.10 wt% gel and the upward inflection of τ at 0.10 wt% has been assigned to an increase in the elasticity of the gel with the increase of the agarose concentration in the range of >0.10 wt% (Region III). On considering the concentration dependence of the surface tension of agarose-water mixtures, the discontinuous and inflection points were assigned to the 1st- and 2nd-order phase transition concentrations of the agarose gel, respectively. Given the results with our tensiometry based on the optical bubble pressure method, distinct gelation points for other systems could be determined both mechanically and thermodynamically which will provide a diagnostic criterion of sol-gel transitions.

Surface tension of binary mixtures composed of N, N-dimethylcyclohexylamine and alcohols at different temperatures

Surface tension (γ) for five binary mixtures containing N, N-dimethylcyclohexylamine (DMCA) and alcohol, ethanol, n-propanol, iso-propanol, n-butanol or iso-butanol were measured over the whole range of composition at 0.1 MPa and different temperatures ranging from (288.15 to 308.15) K. From the experimental data, the surface tension deviations (δγ) for the binary mixtures were calculated. The δγ values are positive for all the studied systems and increase with the decreasing of alky chain length of alcohol. For the mixture containing the branched alkyl alcohol, the increase is significant compared with the equivalent molecules with straight chains. According to temperature dependence of surface tension, the thermodynamic parameters, surface enthalpy (Hγ) and surface entropy (Sγ) were also estimated and further discussed.

Predicting the surface tension of mixtures of fatty acid ethyl esters and biodiesel fuels using UNIFAC activity coefficients

This work presents the use of a formal thermodynamic model together with UNIFAC activity coefficients model, without any further adjustable parameter, to predict the surface tension of biodiesel fuels based on the equality of chemical potentials between the vapor-liquid interface and liquid bulk. The biodiesel samples included in this work were reported previously in the open literature. They were produced from vegetable oils such as: canola, coconut, corn, cottonseed, hazelnut, lard, palm, peanut, rapeseed, safflower, soybean, sunflower, and Walnut. Surface tension values for 18 samples of binary, ternary and quaternary mixtures of fatty acid ethyl esters (FAEEs) at T = 298.15 were predicted with an average absolute relative deviation (AARD) = 1.39%. Surface tension values for 31 biodiesel samples composed by fatty acid methyl esters (FAMEs) were also predicted at temperatures from 303.15 K to 353.15 K. The AARD value obtained for the 78 experimental points of biodiesel samples was 1.86% which shows a very good agreement with experimental measurements. In the UNIFAC method, predictions of surface tension values for the mixtures are based on the knowledge of the values of the surface tension for the pure components; these values were obtained from different sources. Also, two simple mixing rules on mass and mole fraction basis were used to predict the surface tension of biodiesel fuels. The AARD value obtained from the comparison between experimental and calculated values were: 2.77% and 2.91% for mixing rules on mass and mole fractions, respectively.

Surface tension of multicomponent organic mixtures: Measurement and correlation

The study of the surface tension of multicomponent mixtures had attracted the attention of several researchers due to its importance in many engineering applications. In this study, surface tension (σ) and density (ρ) of ternary systems {nonane + toluene + cyclooctane, nonane + benzene + cyclooctane, hexadecane + toluene + cyclooctane, and hexadecane + benzene + cyclooctane} were measured at temperatures of 298.2 K, 303.2 K, 308.2 K and 313.2 K at atmospheric pressure, and different mole fractions. The surface tension of these organic mixtures was measured using DuNouy Ring Device. The results were compared with the existing theoretical values obtained from Brock-Bird correlation and Goldsack-Sarvas method and the average absolute relative deviations (AAD %) were obtained as 7.89% and 3.20%, respectively. In this work we have proposed a new empirical model for correlating the surface tension of the studied multicomponent organic mixtures with an overall average absolute relative deviation of 1.83%. The calculated deviations indicate a reasonable agreement between predicted and experimental values especially for the values obtained from the new proposed model.

Prediction of surface tension of the binary mixtures containing ionic liquid using heuristic approaches; an input parameters investigation

In this study, the effect of input parameters on the performance of the artificial neural network (ANN) has been investigated to predict the surface tension of the 33 non-ionic + ionic liquids binary mixture. To achieve this purpose, in this work, 8 various approaches for input parameters are considered. Physical properties such as temperature, reduced temperature, critical temperature, critical pressure, critical volume, molecular weight, acentric factor and critical compressibility factor as well as two different mixing rules have been used to prepare various input parameters approaches. The root mean square error (RMSE) of the most accurate approach, obtained for all 1537 data points regarding 33 binary mixtures, is 7.88 × 10−3. Furthermore, five different other intelligence methods such as ANFIS, ANFIS-ACO, ANFIS-DE, ANFIS-GA, and ANFIS-PSO have been applied to estimate the surface tension of the concerned binary mixtures based on the best input parameters. The comparison between the results of the ANN and five other methods show that the ANN method has the best accuracy.

Mechanistic Study on Surface Tension of Binary and Ternary Mixtures Containing Choline Chloride, Ethylene Glycol and Water (Components of Aqueous Solutions of a Deep Eutectic Solvent, Ethaline)

Abstract The paper reports the results of the measurement of surface tension in binary liquid mixtures containing choline chloride, ethylene glycol and water and ternary mixtures of ethaline (a eutectic mixture of ethylene glycol and choline chloride, the so-called deep eutectic solvent) with water. The surface tension is determined in a wide range of components’ concentration for the temperatures of 25, 30, 40, 50, 60 and 70 °C. The dependences of surface tension on the concentration of liquids are treated by means of Gibbs adsorption isotherm and linear form of Langmuir adsorption isotherms. The values of the equilibrium constant of adsorption at the interface liquid solution/air as well as the standard adsorption Gibbs energy, enthalpy and entropy are calculated for the binary and ternary mixtures under consideration. The obtained results are interpreted in the light of intermolecular interactions in fluids. Our findings show that ethylene glycol and choline cation interact with each other in the adsorbed surface layer formed at the interface between air and diluted solutions of ethaline.

Supplement to Calculating Vapor–Liquid Surface Tension According to Gibbs

Expressions for calculating Gibbs vapor–liquid surface tension σ are generalized to allow for the interaction between comparable components of a mixture with an arbitrary radius of the interaction potential. Calculations are performed within a modified lattice gas model reflecting a discrete-continuous distribution of mixture components in space with allowance for direct correlations in a quasi-chemical approximation. The calculating of σ is associated with the rejection priority of mechanical characteristics over chemical potential, which is traditional in continuum mechanics. The chemical potential governs local equilibrium distributions of components in the transitional region of a boundary, resulting in the need to use microscopic Gibbs–Duhem equations in a deformed lattice structure of a substance to determine the average distance between molecules (as lattice structure parameters) and to consider effective one-particle motions of components in a dense phase that alter these parameters. Calculations of the surface tension of dense mixtures in models ignoring the existence of vacancies and structural deformation are discussed.

Densities, Vapor Pressures, and Surface Tensions of Selected Terpenes

The knowledge of physico-chemical properties of terpenes and terpenoids are necessary for understanding of formation of cloud condensation nuclei. In this work properties of $$\upalpha$$ -pinene and $$\upbeta$$ -pinene, namely liquid densities, saturated vapor pressure, surface tension and interfacial tension in mixtures with water were measured in the temperature range between 300 and 370 K. Saturated vapor pressures were also modelled by COSMO-RS and compared both with our mesurements and literature values measured at lower temperatures. A modern nonstatistical technique based on mathematical gnostics was used for data analysis.