Surface Tension Of Mixture Research Articles

Calculation of surface tensions for liquid mixtures using the SWCF‐VR EOS and Butler‐type method

AbstractA generalized surface tension model for various types of liquid mixtures by coupling the equation of state for square‐well chain fluids with variable ranges and Butler type method was presented. Transferable molecular parameters fitted from experimental pVT of pure fluids were used. The reliability of this model were tested with liquid mixtures including 87 conventional fluid mixtures, 20 aqueous alcohol‐amine solutions, 12 ionic liquid solutions, 7 polymer solutions, and 4 liquid alloys. The overall average absolute deviations in correlations with one parameter for all binary mixtures, in predictions for all conventional binary mixtures except aqueous solutions and for all ternary mixtures are 1.94%, 1.82%, and 2.69%, respectively. The potential application of the model in simultaneously describing the phase equilibrium and surface tensions was partially verified. The results demonstrate that this model has an overall robustness and reliability in calculations of surface tensions for various liquid mixtures.

Interaction of miscible solutions and superhydrophobic surfaces

ABSTRACTThe complex composition in industrial pollutants includes immiscible liquid and miscible solution that present a great challenge to deal with the effluent. In this research, the interaction between super hydrophobic surface and the miscible solution is studied based on surface tension (ST) and contact angle. A superhydrophobic surface is fabricated by simple anodisation and self-assemble method. Then two different types of miscible solution are adopted to evaluate the property of the superhydrophobic surfaces. The obtained result shows that the wettability is closely related to ST of mixtures, which is controlled by the interface component. When the ST is less than 31.55 mN m−1, the critical pressure reduced from maximum value (6442.8 Pa) to negative number. In turn, the superhydrophobic film loses its repellency and shows affinity to the mixtures. This can provide an important supplement for utilising superhydrophobic materials, especially for the oil–water separation.

Enhancing the pro-health and physical properties of ice cream fortified with concentrated golden berry juice.

Ice cream is a product rich in calories, due to its high carbohydrate, protein, and fat contents, but poor in antioxidants, fibers, and vitamins. The golden berry is a fruit rich in phenols, fibers, minerals, and vitamins. This study was carried out to improve the functional properties of ice cream by incorporating concentrated golden berry juice (CGBJ) in its formulation. The fresh juice of mature golden berries was concentrated (41.01% total solids) and added at the level of 0, 3, 6 and 10% respectively to the ice cream formulations. The CGBJ contained a high level of total soluble solids (37.69 Brix), total phenolic compounds (21.31 mg TAE/100 g) and ascorbic acid (97.15 mg/100 g). It was also rich in some elements, including K (1522.8 mg/100 g), Fe (9.49 mg/100 g) and Zn (3.05 mg/100 g). The antioxidant activity of CGBJ measured using DPPH and ABTS methods were 440.4 and 420.4 μg TE/g, respectively. The acidity, surface tension, and apparent viscosity of the ice cream mixture increased, but the pH value and freezing point decreased as the level of CGBJ in the formulation increased. The addition of 6% CGBJ improved both the whipping ability and overrun of the ice cream with more acceptability and quality. Inversely, ice cream containing 10% CGBJ had the lowest overrun and melting properties, while also having the highest fat destabilization compared to any other ice cream. The physical and sensory properties of ice cream can be improved by adding CGBJ up to 6%. In addition, CGBJ can be used to produce a functional ice cream rich in bioactive components including antioxidants, vitamins, and some elements.

Surface tension and interfacial compositions of binary glycerol/alcohol mixtures

The main aim of this research was to study the surface tension and interfacial composition of different binary mixtures of glycerol and alcohols. To achieve this aim, mixtures of glycerol and ethanol, 1-propanol, 2-propanol, and 1-butanol were prepared. By using the Du-Nouy ring method, surface tensions were experimentally measured as a function of composition in the temperature range of (293–333) K. The equality of chemical potentials of components at the surface layer and bulk liquid was considered for simultaneous prediction of surface tension and composition. The model was employed by using different approaches, including an activity based and a fugacity-based method. The UNIFAC activity model and PSRK EOS were used to calculate the activity and fugacity coefficients, respectively. The results of this study showed that the ability of the activity-based approach is limited (overall AADσ = 26.78%) while the fugacity-based method successfully predicted the surface tensions of the studied mixtures (overall AADσ = 1.84%). Our hypothesis is that the fugacity-based method was more accurate because it accounted for the partial molar area of the components.

Invariance of experimental observables with respect to coarse-graining in standard and many-body dissipative particle dynamics.

Dissipative particle dynamics (DPD) is a well-established mesoscale simulation method. However, there have been long-standing ambiguities regarding the dependence of its (purely repulsive) force field parameter on temperature as well as the variation of the resulting experimental observables, such as diffusivity or surface tension, with coarse-graining (CG) degree. Here, we rederive the temperature dependence of DPD interaction parameter and revisit the role of the CG degree in standard DPD simulations. Consequently, we derive a scaling of the input variables that renders the system properties invariant with respect to CG degree and illustrate the versatility of the method by computing the surface tensions of binary solvent mixtures. We then extend this procedure to many-body dissipative particle dynamics and, by computing surface tensions of the same mixtures at a range of CG degrees, demonstrate that this newer method, which has not been widely applied so far, is also capable of simulating complex fluids of practical interest.

Surface tension measurements of aqueous 1-alkyle-3-methylimidazolume tetrafluoroborate {[Cnmim][BF4] (n = 2, 4, 6)} solutions and modeling surface tension of ionic liquid binary mixtures using six various models

The surface tension of three ionic liquids: [C2mim][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate), [C4mim][BF4] (1-butyl-3-methylimidazolium tetrafluoroborate) and [C6mim][BF4] (1-hexyl-3-methylimidazolium tetrafluoroborate) blended with water were measured at temperatures from (298.15 K to 338.15) K and whole range of mole fraction. The measurements show that studied systems are highly nonideal and surface tension decrease as temperature rises in a linear order. In following, to describe the surface tension of the solutions as a function of temperature and concentration, simultaneously, a new model based on thermodynamics was developed using the nonelectrolyte NRTL nonrandom factor (N-NRTL-NRF) equation. Also, a comprehensive dataset consist of 19 binary ionic liquid solutions with 989 data points at various conditions was collected. The new model, as well as five other models, were applied to the dataset and the performance of the six models was compared to experiments and to each other. The new model shows a deviation with the experiment as RMSD = 0.4559%.

Surface tension of binary mixtures of (ionic liquid + tributyl phosphate)

In this work, surface tension was determined for binary mixtures of imidazolium based ionic liquids (ILs) and tributyl phosphate (TBP) over the whole composition range at temperatures from (293.15 to 323.15) K and atmospheric pressure. The ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) and 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([Bmim]Tf2N) were used in this work. According to the experimental data, surface tension deviations (δγ) and thermodynamic properties, including surface enthalpy (Hγ), surface entropy (Sγ), enthalpy of vaporisation △lgHmo and Hildebrand solubility parameter (SH), were also calculated. The results show that γ values of ILs are significantly higher than that of TBP. And the contribution of the anion size to the surface tension of ILs follows the order of BF4− > PF6− > Tf2N−, which indicates the low negative charge delocalization of small anion can lead to high γ values. Moreover, the strong electrostatic interactions between cation and anion in ILs result in the higher concentration of TBP at surface. As a result, δγ values for all the studied systems are all negative over the entire range of composition. Additionally, due to the high surface organization of ILs, surface entropies for ILs are much lower than that of TBP.

Surface tension investigation of ionic liquids by using the Pseudolattice theory

The pseudolattice theory can be used to describe the thermodynamic and transport properties of ionic liquids. To determine the surface tension of these systems, the surface area can be related to the pseudolattice cell size. In the pure ionic liquids, due to the great number of ionic contacts, the short-range repulsive ion-ion interactions are significant and the ion-solvent interactions are absent. According to the pseudolattice theory and by using some approximations we obtain a simple linear correlation for the surface tension of ionic liquids. The parameters of this linear regularity can be used to estimate the surface tension in a wide temperature range and to predict the surface tension of binary mixtures of ionic liquids. The trend of change of the calculated surface tensions of mixtures and their values are consistent with the experimental data.

Partial molar surface areas in liquid mixtures. Theory and evaluation in aqueous ethanol

Different definitions for the partial molar surface area (PMSA) of a mixture component are found in the literature. The advanced definition states that it is the change of surface area resultant from the addition of 1 mol of that component to the surface region at constant temperature, T, pressure, p, surface tension and surface amounts of the other components. Estimating this quantity has long been hampered by the fact that a change of composition while holding constant the mixture surface tension cannot be attained in the laboratory. Using formal thermodynamics, a rigorous procedure for the calculation of PMSAs is worked out. As input, it only requires experimentally measurable properties of liquid mixtures and their pure constituents. This PMSA is shown to be comparable to the PMSA defined in terms of Gibbs surface excesses of the components, though not equivalent to the PMSA for changes in composition at fixed T and p only. From their relationship it is argued that the advanced PMSA is made up of two contributions, namely the area alteration at constant T and p, which leads to a change in the mixture surface tension, and an additional area variation for restoring the initial surface tension value. In a binary liquid mixture, the restoring area is necessarily positive for the surface active component and negative for the solvent. A new, robust thermodynamic derivative is used for the calculation of relative adsorptions and molar surface areas. Expressions are obtained for the analytic calculation of different PMSAs in thermodynamically ideal liquid mixtures. Standard molar surface areas are defined, and expressions are given for their calculation from model or experimental quantities. Real and ideal PMSAs of water and ethanol are estimated in their mixtures at 298 K, using literature data. Thermodynamic consistency tests were developed and used to reject some PMSA values in water-rich and ethanol-rich solutions. This unfortunate situation is ascribed to calculation procedures that impose much stress on the experimental data. It is concluded that Rusanov's interpretation of a PMSA as a restoring area only accounts for a small part of this quantity, at least in aqueous ethanol solutions. The surface structure of water + ethanol mixtures is re-examined at the light of PMSA values.

The distinct roles of the anaphylatoxin receptors C5aR1, C5aR2 and C3aR during experimental invasive meningococcal disease

In this study, the experimental surface tensions were measured for aqueous solutions of cetyltrimethyl ammonium bromide, 1-propanol, 2-propanol, and 1-butanol with a pendant drop apparatus. The temperature and pressure of all experiments were 298.15 K and 1 bar, respectively. Subsequently, a model based on the equality of the chemical potential of components at the interface and the bulk liquid was used. The results of this part showed that the surface tensions were reproduced well. The average absolute deviation percent of surface tension was 1.11. Then the surface tensions of (cetyltrimethylammonium bromide + alcohols) aqueous mixtures were measured at different concentrations. Moreover, the critical micelle concentrations of the applied systems were determined. The present model was used for aqueous mixtures of (cetyltrimethylammonium bromide + alcohols). The average absolute deviation percent of surface tension was 2.72, so the model successfully predicted the surface tension for aqueous solutions of (cetyltrimethylammonium bromide + alcohols). Furthermore, the results of the model proved that the presence of alcohols decreased the surface coverage of cetyltrimethylammonium bromide and increased the values of the critical micelle concentration.

Cationic–anionic fluorinated surfactant mixtures based on short fluorocarbon chains as potential aqueous film-forming foam

A strategy for aqueous film-forming foam (AFFF) using cationic-anionic surfactant mixtures with short fluorocarbon chains (≤C4) in both cationic and anionic surfactants was proposed. The minimum surface tension (γmin) of mixtures of C4F9SO2NH(CH2)3N(CH3)3I (C4FI) and CnF2n+1COONa (n = 1, 2, 3, 4) with different molar ratios (5:1, 2:1, 1:1, 1:2, 1:5) was measured at 25 °C. The γmin for all mixtures of C4FI–CnF2n+1COONa were remarkably lower than that of pure C4FI. Among these mixtures, the equimolar mixture of C4FI–C3F7COONa was chosen because of the low γmin, qualified solubility and relatively high fluorine efficiency. The spreading coefficients of its aqueous solution on n-heptane, toluene, benzene, cyclohexane and gasoline were all positive, indicative of its potential in AFFF. The film spreading, sealability and foaming were also tested. The influences of ‘green’ additives (alkyl glucose amide, xanthan gum and sodium carboxymethylcellulose) on foaming performance were studied, in which small dosage of xanthan gum could greatly retard the drainage of foam. It was confirmed that the mixing of oppositely charged surfactants both possessing short fluorocarbon chains was a valuable thought to design AFFF. In application, the quaternary ammonium surfactant likewise can be bromide or chloride rather than iodide for reasons of cost-reduction and stability.

Effect of Gelation on the Colloidal Deposition of Cellulose Nanocrystal Films.

One of the most important aspects in controlling colloidal deposition is manipulating the homogeneity of the deposit by avoiding the coffee-ring effect caused by capillary flow inside the droplet during drying. After our previous work where we achieved homogeneous deposition of cellulose nanocrystals (CNCs) from a colloidal suspension by reinforcing Marangoni flow over the internal capillary flow (Gençer et al. Langmuir 2017, 33 (1), 228-234), we now set out to reduce the importance of capillary flow inside a drying droplet by inducing gelation. In this paper, we discuss the effect of gelation on the deposition pattern and on the self-assembly of CNCs during droplet drying. CNC films were obtained by drop casting CNC suspensions containing NaCl and CaCl2 salts. A mixed methodology using rheological and depolarized dynamic light scattering was applied to understand the colloidal behavior of the CNCs. In addition, analysis of the mixture's surface tension, viscosity, and yield stress of the suspensions were used to gain deeper insights into the deposition process. Finally, the understanding of the gelation behavior in the drying droplet was used to exert control over the deposit where the coffee-ring deposit can be converted to a dome-shaped deposit.

Toward Development of a Universal CP-PC-SAFT-Based Modeling Framework for Predicting Thermophysical Properties at Reservoir Conditions: Inclusion of Surface Tensions

This study presents an approach for predicting surface tensions (ST) of mixtures coupling the critical-point-based perturbed-chain statistical association fluid theory (CP-PC-SAFT) and the square gradient theory (SGT). This modeling framework implements standardized and transparent parametrization procedures. As an input it requires the pure compound critical temperatures and pressures along with the triple point densities and surface tensions, without further adjustment to ST data of mixtures. Its predictions of a major part of the existing surface tension data on asymmetric binary systems, including the aqueous solutions, in the entire available range of conditions, are discussed. The results demonstrate that the proposed approach is characterized by a remarkable overall robustness and reliability. However, the system toluene (1)–water (2) poses a clear limitation to its predictive implementation. Predictions of CP-PC-SAFT coupled with the generalized modified Yarranton–Satyro correlation for the recent...

A classical density functional theory for vapor-liquid interfaces consistent with the heterosegmented group-contribution perturbed-chain polar statistical associating fluid theory

A Helmholtz energy functional consistent with the heterosegmented group-contribution perturbed-chain polar statistical associating fluid theory (GC-PCP-SAFT) is developed in this study and is applied to predict interfacial properties of planar vapor-liquid interfaces. Predicted surface tensions of pure substances are in very good agreement with experimental data for systems of non-polar as well as polar compounds including biodiesel systems where the group-contribution approach proves especially advantageous. The average deviation of the proposed model from experimental data is only 5% for these substances. Short hydrogen-bonding compounds, such as methanol and ethanol, are not predicted convincingly well. For longer hydrogen-bonding molecules the results are satisfying and deviations decrease to values of 3–10% for the entire liquid-vapor region. The orientation of hydrogen-bonding molecules at the vapor-liquid interface is reproduced qualitatively by the proposed model. Surface tensions for mixtures (including mixtures with hydrogen-bonding components) are predicted surprisingly well, with average deviations from experimental data of 5%. For mixtures, transferable group-group interaction parameters are adjusted to binary vapor-liquid equilibria data. The description of vapor-liquid phase equilibria is thereby significantly improved, however, the improvement of predicted surface tensions is mild. Further, in order to compensate for a weakness of group-contribution equations of state, we propose a concept for individualizing the group-contribution approach for substances that are well characterized by experimental data. We introduce a component-specific parameter. This concept improves the description mostly of vapor pressures, especially for short and multi-functional molecules. The effect of this measure on predicted surface tensions, however, is very modest.

Toward an intelligent approach for predicting surface tension of binary mixtures containing ionic liquids

Knowledge of the surface tension of ionic liquids (ILs) and their related mixtures is of central importance and enables engineers to efficiently design new processes dealing with these fluids on an industrial scale. It’s obvious that experimental determination of surface tension of every conceivable IL and its mixture with other compounds would be a herculean task. Besides, experimental measurements are intrinsically laborious and expensive; therefore, accurate prediction of the property using a reliable technique would be overwhelmingly favorable. To do so, a modeling method based on artificial neural network (ANN) trained by Bayesian regulation back propagation training algorithm (trainbr) has been proposed to predict surface tension of the binary ILs mixtures. A total set of 748 data points of binary surface tension of IL systems within temperature range of 283.1-348.15 K was used to train and test the applied network. The obtained results indicated that the predictive values and experimental data are quite matching, representing reliability of the used ANN model for such purpose. Also, compared with other methods, such as SVM, GA-SVM, GA-LSSVM, CSA-LSSVM, GMDH-PNN and ANN trained with trainlm algorithm the proposed model was better in terms of accuracy.

Calculation of the Surface Tension of Droplets of Binary Solutions of Simple Fluids and the Determination of Their Minimum Size

To describe the surface tension of vapor–liquid interfaces of one- and two-component simple fluids, a molecular theory based on the lattice gas model is applied. The surface tension of mixtures of simple fluids are calculated in a quasi-chemical approximation of an accounting of the intermolecular interactions of the nearest neighbors. The model parameters previously found from experimental data on bulk surface tensions enable calculation of the surface tension of vapor–liquid interfaces of one- and two-component droplets with different sizes as the function of their radius. The minimum size of thermodynamically stable small droplets with the properties of a homogeneous phase inside is estimated.

Density, orientation, solvation and adsorption effects on surface tension of mixtures

The present article offers a novel analysis tool that potentially can be used to describe and characterize the process of interfacial adsorption of both simple molecules and complex molecules (surfactants, biomolecules, etc). This analysis tool was developed for evaluating the influence of the density, orientation, solvation and adsorption effects on the surface tension of mixtures. We propose a procedure that consists in split the excess surface tension function into three additive contributions. That is, a residual function (R) based on the concept of elastic energy density in which both the interfacial density and the axial orientation are taken into account, an enthalpic function (H) considering the solvation effects, and a contribution that includes the preferential adsorption (AD) effects. This approach is referred in this work as RHAD. The AD contribution was assessed using the Langmuir isotherm model. In order to evaluate the reliability of the RHAD method, simple molecular approaches describing each contribution were chosen. Some experimental systems were employed as binary mixtures models for the evaluation of the descriptive capability of RHAD. The experimental data for both complexes and simple binary mixtures were successfully reproduced. Thus, this methodology allowed us to quantitatively and qualitatively incorporate the influence of molecular parameters on the experimentally observed behavior of this important physical property. Also, the results shown that when one of the contributions domains over the others, the overall behavior of the surface tension of the binary mixture is mainly led by the difference between the surface tensions (π0) and the ratio of the molar volumes (V2/V1) of their pure components. Meaningful deviations from ideal behavior and the occurrence of aneotropy can be further interpreted employing RHAD. Finally, our results suggest that the adsorption process is better understood by considering the interfacial width.

Theoretical Estimation of Surface Tension for Binary Mixtures at Different Temperatures

Theoretical Estimation of Surface Tension for Binary Mixtures at Different Temperatures

New experimental and modeling based on the N-Wilson-NRF equation for surface tension of aqueous alkanolamine binary mixtures

In this work, surface tension of aqueous solutions of various alkanolamines; monoethanolamine (MEA), diethanolamine (DEA), diisopropanolamine (DIPA), N-methyldiethanolamine (MDEA) and Sulfolane at the temperature range of 298.15–348.15 K and mole fraction ranges of 0–1 are determined. In the studied temperature range, the experimental surface tension values of the binary mixtures increase as the water concentration increases and decrease as the temperature increases. In following, the surface tension results for the binary solutions were correlated simultaneously as a function of temperature and concentration. For this purpose based on a thermodynamic definition of surface tension and the expression of Gibbs free energy, a new surface tension equation is proposed. This new equation is developed by using the nonelectrolyte Wilson nonrandom factor (N-Wilson-NRF) model to represent the excess Gibbs free energy of the system. The model parameters obtained by correlating binary surface tension at two different approaches. In one approach the parameters are assumed as non-temperature dependent and in another approach, a linear temperature dependency is considered. The comparison between the results of the presented model with experimental data and four other models show that the new equation is simple and more accurate in the correlation of these studied systems.

Surface tension of aqueous binary mixtures under the supercooled conditions – Development of the measuring technique and preliminary data for water + lower alcohols

An experimental apparatus originally developed for the measurement of surface tension of supercooled water was modified such that it allows for measurement of binary aqueous mixtures. The measuring principle based on the capillary rise technique is similar to that employed in the previous measurements with pure water [J. Hrubý et al., J. Phys. Chem. Lett. 5 (2014) 425 and V. Vinš et al., J. Phys. Chem. B 119 (2015) 5567]. The temperature dependence of the surface tension is determined from the measured height of the liquid column elevated in a vertical capillary tube with an inner diameter of 0.32 mm. The aqueous liquid rises to a height of 60 mm to 95 mm depending on the solute concentration and the temperature. Preliminary tests performed with the binary mixtures of water with methanol, ethanol, and n-propanol at various concentrations and temperatures down to –28 °C approved functionality of the measuring technique. Some difficulties, such as influence of impurities on the liquid column elevation or formation of bubbles in the liquid column, were observed. The experimental apparatus is further being modified in order to obtain more accurate data for various aqueous mixtures.