Surface Tension of Binary Mixtures of 1-Alkyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids with Alcohols

New experimental surface tension data have been provided at 283.15, 298.15, 313.15 K and atmospheric pressure for binary mixtures of 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide and 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with the alcohols: methanol, ethanol, 1-propanol, 2-propanol, l-butanol and 1-pentanol. The experimental results show that the surface tensions of these mixtures depend systematically on the alkyl chain length of the ionic liquid and alcohol, composition and temperature. Surface tension changes on mixing have been calculated and adequately fitted by the Redlich–Kister polynomial equation. The adjustable parameters and the standard deviations between experimental and calculated values are reported.     

Surface tension of binary and two ternary mixtures containing water–acetonitrile–methanol/ethanol at 298.15 K: experimental data,correlation and prediction by various models

Surface tension of two ternary mixtures of water/acetonitrile/methanol and water/acetonitrile/ethanol, and their constituent binaries, were measured over the whole range of composition at 298.15 K and ambient pressure. The experimental data were used to calculate in the surface tension deviations (Δσ). The negative values of Δσ for the binary and ternary systems indicate the strong hydrogen bonding between unlike molecules of mixtures (particularly in the high concentration of water). Surface tension data of the binary systems were correlated with Fu et al., Wang–Chen, Redlich–Kister and Myers–Scott models. The mean standard deviation obtained from the comparison of experimental and calculated surface tension values for binary systems with four models is less than 0.42. Finally, the concentration dependence of the surface tension deviation of the ternary mixtures at 298.15 K was correlated using Pando et al. and Ku et al. models, with satisfactory results.     

Surface Tension of Ternary Liquid Mixtures

Abstract

Surface tension has been measured by the differential capillary rise method for three ternary mixtures containing alkanes (hexane + cyclohexane+benzene, pentane + hexane + benzene and cyclohexane + heptane + toluene at 298.15\pm 0.1°K). The sign and magnitude of the excess surface tension and excess volume depend ultimately upon the chain length of the component of the mixtures. The results of the surface tension were compared with theoretical values obtained from Flory theory, Sanchez method, Brock-Bird relation and volume fraction statistics. There is reasonable agreement between theory and experiment.     

Theoretical consideration of the anomalous temperature dependence of the surface tension of pure liquid gallium

The surface tension of pure liquid gallium in the temperature range 303–503 K (303 K is the melting point) was previously measured using the noninvasive method of capillary wave spectroscopy (CWS). The result of this experiment showed that the value of surface tension increases from 303 to 345 K indicating a negative surface excess entropy (S ^σ), and decreases linearly from ~345 to 503 K confirming a negative slope, and thus a positive S ^σ. This unusual behavior of Ga is not known for other liquid metals such as Bi, Pb, Hg, Sn and Al. The reported experimental behavior is modeled here. A theoretical equation for calculating the surface tension of liquid Ga, based upon formulating a proper partition function that includes the rotational part, is derived and described. The theory predicted no maximum in the temperature-dependence of the surface tension, as seen in the experiment, where the analysis was done over a large temperature range (325–503 K). The value obtained from this mathematical expression indicates that the temperature variation of surface tension has no positive slope within the temperature range 303–345 K. At T > 345 K, the surface tension shows the usual linear temperature-dependence with a negative slope. Therefore, the equation is only applicable for the latter temperature range. A comparison between the theoretical and experimental values of surface tension of liquid Ga is discussed.     

Prediction of surface tension and surface concentration of binary refrigerant system (R290/R600a) at various temperatures and pressures

The surface tension of a binary refrigerant mixture of R290(propane: C₃H₈) and R600a(isobutane:i-C₄H₁₀) has been calculated by using critical constants (P_c, V_c and T_c) and acentric factor (ω) at three isotherms of 278 K, 300 K and 320 K over the pressure range from 187.7 to 1540.2 kPa. In this paper, new formalism has been made by using simple mixing rule for modifying the predictive models: Brock–Bird, Pitzer, Hakim et al., Bolotin, Sastri–Rao and Zuo–Stenby. On comparing the computed values of surface tension with experimental data, satisfactory results have been observed. The average absolute deviation (AAD) obtained from the comparison of experimental and calculated surface tension values for six models is less than 1.9%. Finally, in a new approach, the extended Langmuir model (EL) was used to finding more information about the surface structure and surface concentration of binary refrigerant mixtures.     

Surface tension measurements with validated accuracy for four 1-alkyl-3-methylimidazolium based ionic liquids

Air–liquid interfacial surface tension measurements are reported on four 1-alkyl-3-methylimidazolium ([C_n-mim], n = 2, 4, 6) based ionic liquids at 15 temperatures from (283 to 353) K at atmospheric pressure. To validate the accuracy of the results, the Wilhelmy plate method and the du Noüy ring method were employed in parallel, using the Kr?ss K100MK2 tensiometer. At each temperature from 29 to 44 individual readings were taken. The surface tension average values at particular temperatures are presented with the estimated overall standard uncertainty ranging from (±0.025 to ±0.1) mN · m^?1. An empirical surface tension–temperature equation has been developed describing the temperature dependence of each ionic liquid surface tension. Some details of the measurement procedure that have been found to be important in achieving the highest possible accuracy are discussed.     

Effect of Glyphosate Isopropylamine on the Surface Tension and Surface Dilational Rheology Properties of Polyoxyethylene Tallow Amine Surfactant

In order to develop the substitutes for polyoxyethylene tallow amine (POEA), the understanding the interaction of glyphosate isopropylamine and POEA is essential. The surface behaviors of POEA and POEA in the presence of 1 wt% glyphosate isopropylamine have been investigated at the air-water interface by the drop shape analysis method. The influences of surface tension, dilational frequency, and bulk concentration on the surface properties were expounded. The experiment results show that the adsorption films of POEA behave elastic in nature at low bulk concentration. With increasing in bulk concentration, the dilational modulus, dilational elasticity, and dilational viscosity pass through a maximum value, the phase angle increase monotonically. These phenomena can be attributed to the diffusion-exchange process between the bulk and the interface. The addition of 1 wt% glyphosate isopropylamine significantly influences on the POEA surface tension and dilational properties. The dilational modulus, dilational elasticity, and dilational viscosity obvious decrease in general, and the values of phase angle significant change after the addition of 1 wt% glyphosate isopropylamine. Glyphosate isopropylamine and POEA form a new complex in the solution and the surface activity and surface dilational properties of complex is different from POEA.     

全氟辛酸铵与全氟壬酸铵混合物的表面活性

测定了全氟辛酸铵和全氟壬酸铵及其不同比例混合物的0.1mol/L氯化铵水溶液表面张力曲线。讨论了它们的胶团化作用、吸附作用和降低水表面张力的能力。改进了Ingram-Luckhurst自单一表面活性剂活性张力曲线得到混合溶液表面张力曲线的方法。     

The Prediction of Surface Tension and Thermodynamic Analysis of the Surface in Mixtures of Cryogenic Liquids

The surface tensions of 42 binary cryogenic mixtures at low temperature are correlated using the Shereshefsky model and excellent results are obtained. The average percent deviation is about ～ 1.08%. The Gibbs energy change in the surface region is calculated and is used to obtain the excess number of molecular layers in the surface region. Furthermore, the model is used to derive an equation for the standard Gibbs energy of adsorption. The experimental standard Gibbs energy of adsorption is obtained from surface tension data and compared with calculated data. The agreement between experimental and calculated data is found to be very good. The magnitude of the Gibbs energy change in the surface region and the standard Gibbs energy of adsorption are discussed in terms of nature and type of intermolecular interactions in binary mixtures.     

Preparation of Water-in-Diesel Fuel Nanoemulsions Using High-Energy Emulsification Method and a Study of Some of Their Surface Active Properties

In this work, formations of water-in-diesel fuel nanoemulsions using water/mixed nonionic surfactant/diesel fuel system has been studied. The high-energy emulsification method was used to form three emulsions using different water contents: 5, 10, and 14% (v/v) namely; E1, E2, and E3, respectively. These nanoemulsions were stabilized with emulsifiers having different hydrophilic lipophilic balance (HLB), namely, Span 80 (HLB = 4.3), Emarol 85 (HLB = 11), and their mixture (SE) with HLB = 10. The effect of water on the droplet size formation has been investigated. The interfacial tension and thermodynamic properties of the individual and emulsifiers blends have been studied. The interfacial tension (γ) measurements at 30°C were used to determine the critical micelle concentration (CMC) and surface active properties of these emulsifiers. The water droplet sizes were measured by dynamic light scattering (DLS). From the obtained data, it was found that mean sizes between 19.3 and 39 nm were obtained depending on the water content and concentration of blend emulsifiers (SE). Also, the results show that the interfacial tension (γ) gives minimum value (10.85 mN/m) for SE comparing with individual emulsifier (17.13 and 12.77 mN/m) for Span 80 and Emarol 85, respectively. The visual inspection by transmission electron microscopy showed that the obtained results support the data obtained by dynamic light scattering.     

Surface Tension Measurements for Binary Mixtures of Chlorobenzene or Chlorocyclohexane + Tetrahydrofuran at 298.15 K

Surface tensions (σ) for the binary mixtures chlorocyclohexane + tetrahydrofuran and chlorobenzene + tetrahydrofuran at 298.15 K and 1.013 bar have been determined as a function of the mole fraction. In order to analyze the surface tension behavior, the extended Langmuir (EL) and Shereshefsky models were used and parameters of the models were obtained for these mixtures. The standard Gibbs energy of adsorption (\( - \Delta G^{\circ} \)) was calculated using both models. The Gibbs energy change for replacing 1 mol of solute with 1 mol of solvent in the surface region (?G _S), and the excess number of molecular layers of solute in the surface region, were calculated using Shereshefsky’s model. The magnitudes of ?G _S and \( - \Delta G^{\circ} \) are discussed in terms of the nature and type of intermolecular interactions in the binary mixtures.     

A Solution State Study of the Complexation and Thermodynamic Parameters of Binary Complexes of the Inner Transition Metals with Piracetam in Aqueous and Mixed Solvents

An equilibrium study on complexation behavior of the inner transition metals, where M = {Y(III), La(III, Ce(III, Pr(III), Nd(III), Sm(III), Gd(III), Dy(III), Th(IV)} and L = piracetam, has been carried out using the Irving–Rossotti titration technique in aqueous media at different temperatures and ionic strengths. The protonation constant and stability constants (log₁₀ β _n ) of the resulting inner metal–ligand complexes have been calculated with the Fortran IV program BEST using the method of least squares and considering the BESTFIT model. Thermodynamic parameters were also evaluated, yielding negative ΔG°, ΔH° and positive ΔS° values that indicate complex formation is favorable at ordinary temperatures. Species distribution curves of complexes have been plotted as function of pH using the SPEPLOT FORTRAN IV program to visualize the presence of various species in equilibrium in the pH range 2–6. To understand more about these equilibria, the stability of these complexes was studied at different percentages of solvent (10–30 % v/v) in different aqua-organic solvent mixtures with methanol, ethanol, 1-butanol and dimethylformamide.     

Surface and Solution Properties of Cationic Gemini Surfactants with Primary Linear Alkanols

Using surface tension and fluorescence methods, the surface and solution properties of two cationic gemini surfactants {pentanediyl-1,5-bis(dimethylcetylammonium bromide) and hexanediyl-1,6-bis(dimethylcetylammonium bromide)} (referred to as 16-5-16 and 16-6-16) have been studied in the presence and absence of primary linear alkanols. Parameters studied include the critical micelle concentration (CMC), C ₂₀ (the surfactant concentration required to reduce the surface tension of the solvent by 20 mN·m^?1), Г _max (maximum surface excess), and A _min (minimum surface area per molecule). These parameters indicate mixed micelle formation and, therefore, surfactant-additive interaction parameters in mixed micelles and mixed monolayers, as well as activity coefficients, were calculated. A synergistic effect was observed in all instances and was found to be correlated with the chain length of the alkanols. The CMC values of 16-s-16 (s = 5, 6) decrease with increasing alkanol concentration and the extent of this effect follows the sequence: 1-octanol (C₈OH) > 1-heptanol (C₇OH) > hexan-1-ol (C₆OH) > 1-pentanol (C₅OH) > butanol (C₄OH). The micelle aggregation number (N _agg) of mixed micelles has been obtained using the steady state fluorescence quenching method. The micropolarity of gemini/alkanol systems has been evaluated from the ratio of intensity of peaks (I ₁/I ₃) of the pyrene fluorescence emission spectra. Results are interpreted on the basis of the structure of mixed micelles and monolayers.     

Surface tension and density of binary mixtures of monoalcohols,water and acetonitrile: equation of correlation of the surface tension

Measurements of the surface tension (σ) and density (ρ) of binary mixtures of monoalcohols, water and acetonitrile at 298.15 K and at atmospheric pressure, as a function of mole fraction (x) have been made. The experimental values of the deviation of surface tension and the excess of molar volume (Δσ, V ^E) have been correlated by the Redlich–Kister equation. An empirical correlation equation is presented for the study of the surface tension of these mixtures, and comparisons are made of the experimental values of surface tension versus those obtained with the correlation equation and with other models of correlation. Finally, with the purpose of corroborating the validity of the correlation equation, the latter is applied to other reference binary mixtures.     

Corrosion Inhibition Efficiency in Relation to Micellar Interaction Parameters of Cationic/Nonionic Surfactant Mixtures for Carbon Steel Pipelines in 1 M HCl Solution

The effect of different nine molar mixed ratios of didecyl dimethyl ammonium chloride as a cationic surfactant and nonyl phenol ethoxylate (e.o. = 9) as a nonionic surfactant, on the inhibition behavior of carbon steel have been examined using the weight loss and the potensiodynamic methods. The results show that these mixed cationic/nonionic surfactant mixtures (II to X) can be used to inhibit the corrosion of steel pipelines in the petroleum acid job. The surface active properties of the used surfactant mixtures were calculated using the surface tension measurements and the critical micelle concentration (CMC) values. The micellar interaction parameters of the investigated mixtures were calculated using the data of CMC. From the corrosion results it was found that, the maximum synergistic effect was obtained by the mixtures VIII (30%C + 70%N) and IV (70%C + 30%N). They exhibited inhibition efficiency expressed by the rate of corrosion as 5.15 and 1.53 miles per year respectively, at 400 ppm. The positive synergistic behavior of these mixtures pronounced the better results than which obtained by the individual inhibitors (cationic or nonionic alone). At the same time the maximum micellar interaction parameter was obtained by the mixtures VIII and IV (?1.85 and ?1.80, respectively). These results justified the strong relationship between the corrosion inhibition efficiency and the micellar interaction parameters of the mixed surfactants which used as an organic corrosion inhibitors.     

Effect of volume concentration and temperature on viscosity and surface tension of graphene–water nanofluid for heat transfer applications

In the present study, the effect of volume concentration (0.05, 0.1 and 0.15 %) and temperature (10–90 °C) on viscosity and surface tension of graphene–water nanofluid has been experimentally measured. The sodium dodecyl benzene sulfonate is used as the surfactant for stable suspension of graphene. The results showed that the viscosity of graphene–water nanofluid increases with an increase in the volume concentration of nanoparticles and decreases with an increase in temperature. An average enhancement of 47.12 % in viscosity has been noted for 0.15 % volume concentration of graphene at 50 °C. The enhancement of the viscosity of the nanofluid at higher volume concentration is due to the higher shear rate. In contrast, the surface tension of the graphene–water nanofluid decreases with an increase in both volume concentration and temperature. A decrement of 18.7 % in surface tension has been noted for the same volume concentration and temperature. The surface tension reduction in nanofluid at higher volume concentrations is due to the adsorption of nanoparticles at the liquid–gas interface because of hydrophobic nature of graphene; and at higher temperatures, is due to the weakening of molecular attractions between fluid molecules and nanoparticles. The viscosity and surface tension showed stronger dependency on volume concentration than temperature. Based on the calculated effectiveness of graphene–water nanofluids, it is suggested that the graphene–water nanofluid is preferable as the better coolant for the real-time heat transfer applications.     

Surface tension of non-ideal binary and ternary liquid mixtures at various temperatures and p = 81.5 kPa

Experimental surface tensions for binary mixtures (1,2-ethandiol + water), (1,2-ethandiol + acetonitrile), and (acetonitrile + water) at temperatures of 283.15 K, 298.15 K, and 308.15 K and the ternary mixture (1,2-ethandiol/water/acetonitrile) at 298.15 K have been measured with the Du Noüy ring tensiometer. The surface tension of the above mentioned binary and ternary systems were correlated with empirical and thermodynamic based models. The methods of Pando et al. and Ku et al. were used to correlate the ternary surface tension data. The Fu et al., Kalies et al. and Wang et al. models were also applied to predict surface tension in the ternary system. The mean average absolute deviations obtained from the comparison of experimental and calculated surface tension values for ternary system with three models are less than 2.4%, which leads to concluding that these models show a good accuracy in different situations in comparison with other predictive equations.     

A modified square well model in obtaining the surface tension of pure and binary mixtures of hydrocarbons

A model based on the perturbation theory of fluids was proposed to correlate the experimental data for surface tension of pure hydrocarbons in a wide range of temperature. The results obtained for the pure hydrocarbons were directly used to predict the surface tension for binary hydrocarbon mixtures at various temperatures. In the proposed model, a modified form of the square well potential energy between the molecules of the reference fluid was taken into account while the Lennard–Jones dispersion energy was considered to be dominant amongst the molecules as the perturbed term to the reference part of the model. In general, the proposed model has three adjustable parameters which are chain length, m, size, σ, and energy, ε/κ, parameters, but in some cases the number of parameters was reduced to two, thereby setting the chain length to be unity for pure hydrocarbons. The regressed values of these parameters were obtained using the experimental data for pure hydrocarbons at different temperatures. The results showed that these parameters can be related to the molar mass of hydrocarbons. The model was also extended to predict the surface tension of binary hydrocarbon mixtures using the parameters obtained for the pure compounds. It is worth noting that no additional parameter has been introduced into the model in the extension of the model to the mixtures studied in this work. The results showed that the proposed model can accurately correlate the surface tension of pure hydrocarbons. Also the results showed that the surface tension for binary mixture of hydrocarbons can be accurately predicted using the proposed model over a wide temperature range.     

Surface tension of four binary systems containing (1-ethyl-3-methyl imidazolium alkyl sulphate ionic liquid + water or + ethanol)

In this work, we present surface tension experimental measurements for eight binary systems containing water or ethanol and an ionic liquid (IL) of the 1-ethyl-3-methyl imidazolium alkyl sulphate family, being the alkyl chain of the anion: ethyl, butyl, hexyl and octyl. Measurements were performed at the temperature of 25.0 °C and atmospheric pressure. All four ILs are completely miscible with water and ethanol, but for a concentration range of the octyl sulphate IL aqueous system the mixture jellifies, and so it is not possible to measure its surface tension. These measurements allow us to study the influence of the anion size on the surface tension for the pure IL compounds, and the role of the two different solvents in the surface tension behaviour. Thus, we observe that it is completely different when mixed with water or with ethanol, as also happens in other mixtures with different ionic liquids. From the experimental data, we extract surface tension deviations using the most popular definition. The calculated deviations for the ethanol based system are fitted using the Redlich–Kister equation and a novel one previously reported by us. Furthermore, we have also calculated the reduced surface pressure for the aqueous mixtures, which is fitted with good agreement using a theoretical equation obtained from the Bahe–Varela pseudo-lattice model.