Surface Tension Of Mixture Research Articles

Thermodynamic properties of binary systems containing 1-allyl-3-methylimidazolium dicyanamide [Amim][DCA] with short chain alcohols and prediction of surface tension based on molar surface Gibbs free energy

BackgroundAllyl functionalized ionic liquids (ILs) are widely used because of their excellent properties, to increase their applications in industry and academic community, preparing binary mixtures containing ILs and organic solvents is an effective way, and it is essential to further explore the thermodynamic properties of them. MethodsHere, we reported the synthesis and characterization of the ILs 1-allyl-3-methylimidazolium dicyanamide [Amim][DCA]. Then, in the temperature range of 288.15 K–318.15 K, the values of density and surface tension of 1-allyl-3-methylimidazolium dicyanamide, methanol, ethanol, propanol and corresponding binary systems were measured at every 5 K in the full molar concentration. The values of surface tension deviation Δγ, excess molar volume VE and molar surface Gibbs free energy gs of the mixtures were calculated. In addition, the modified Eӧtvӧs equation is derived based on gs, and the values of surface tension of binary mixtures are estimated. Significant findingsThe results show VE are negative, which is mainly due to the tight packing and hydrogen bond, the formation of hydrogen bond has been confirmed by infrared spectroscopy. The Δγ values of 1-allyl-3-methylimidazolium dicyanamide + methanol are positive, while that of the other two are negative. The modified Eӧtvӧs equation has a clear physical meaning. Moreover, the predicted values are in good agreement with the measured ones.

Viscosity, surface tension, and density of binary mixtures of the liquid organic hydrogen carrier diphenylmethane with benzophenone

The liquid organic hydrogen carrier (LOHC) diphenylmethane may react to benzophenone in the presence of air, especially at elevated temperatures. Therefore, information about the influence of benzophenone added to diphenylmethane on process-relevant thermophysical properties is required. In the present contribution, the liquid viscosity, surface tension, and liquid density of binary mixtures of diphenylmethane with benzophenone are determined between (283 and 573) K using complementary experimental methods. Investigations on the surface tension by the pendant-drop method and surface light scattering indicate molecular orientation effects of benzophenone at the vapor-liquid interface. With increasing benzophenone content, an increase in density, surface tension, and especially viscosity is found. For the latter property, a distinct change in the temperature dependence is observed at the transition from the liquid to the supercooled liquid state. Furthermore, water dissolved in benzophenone causes changes within 15% and 3% relative to the viscosity and surface tension of benzophenone, respectively. • Surface light scattering and conventional methods applied between 283 and 573 K. • Surface tension measurements indicate surface orientation effects of benzophenone. • Larger density, surface tension, and viscosity with increasing benzophenone content. • Big change in temperature dependence of viscosity from liquid to supercooled liquid. • Dissolved water has minor impact on viscosity and surface tension of benzophenone.

Surface tension measurements and modelling of n-Hexadecane + n-Dodecane, n-Hexadecane + 2,2,4,4,6,8,8-Heptamethylnonane, n-Hexadecane + n-Octacosane and n-Hexadecane + Squalane binary mixtures between (303 and 573) K by pendant drop method

This work contributes to the experimental measurements and modelling of the surface tension for the medium- to long-chained hydrocarbon mixtures involved in the Fischer-Tropsch process under the high-temperature conditions. For this purpose, the experimental surface tension measurements for the four investigated binary mixtures of n-Hexadecane with n-Dodecane, 2,2,4,4,6,8,8-Heptamethylnonane, n-Octacosane and Squalane were performed by pendant drop method at temperatures up to 573.15 K covering the mass fractions of wn-Hexadecane = (0.25, 0.50 and 0.75). The combined expanded uncertainties of temperature, mole fraction and surface tension with a level of confidence of 0.95 (k = 2) are estimated to be 20 mK, within 0.6% and less than 2.2% over the entire temperature, respectively. On the basis of the surface tension correlations of pure substances in our previous study, the experimental surface tension data of the four investigated binary mixtures were correlated with the three-parameter Jouyban − Acree model and two-parameter Fu-Li-Wang (FLW) model. However, the experimental results show increasing negative deviations from Jouyban − Acree model with maximum values up to −2.66% and increasing positive deviations from FLW model with maximum values up to 9.93% in the high temperature zone. Therefore, we proposed a new model for correlating the surface tension of multicomponent mixtures with excellent reproducibility. The relative deviations of the experimental data from the present model are distributed evenly on both sides of the zero line and the relative absolute deviations are within 0.6%.

Density and surface tension of binary mixtures of 1, 2-propylene glycol and glycerol under atmospheric pressure from 303.15 K to 393.15 K and correlating with the Jouyban–Acree model

ABSTRACT In this study, the density and surface tension of binary mixtures of 1,2-propylene glycol (1) + glycerol (2) at the temperature range of 303.15 K to 393.15 K under atmospheric pressure are reported. In addition, the excess molar volume, surface tension deviation, molar volume and molar thermal expansion of the mixture were calculated. Finally, the Jouyban–Acree model was used to correlate the experimental data mathematically, and the accuracy of the model was verified by using the mean relative deviation (MRD). The results showed that the MRD between the experimental data and the calculated data of density and surface tension were 0.003 ± 0.007 and 0.023 ± 0.092, respectively. The accuracy of the model is high and can be directly applied to the production and application of some pharmaceutical and liquid industrial products.

Interfacial Properties of Deep Eutectic Solvents by Density Gradient Theory

Deep eutectic solvents (DES) are room-temperature liquid mixtures constituted of a hydrogen-bonding acceptor (HBA) and a hydrogen-bonding donor (HBD). They have high practical potential due to their versatility, quick preparation, and wide applications. Therefore, it is appropriate to have robust models to predict their properties. In this work, the density gradient theory has been combined with the perturbed-chain statistical associating fluid theory to model and understand the interfacial behavior in systems of deep eutectic solvents. DESs were modeled as mixtures of their constituents, and a methodology is proposed for estimating the chemical potential of DESs to extend their study to the interfacial properties. Available experimental data of hydrophilic and hydrophobic DESs were used to calculate the influence parameters, providing a way to linearize them in terms of the molecular parameters of HBDs and their molar ratio between HBD and HBA. This treatment has made it feasible to predict the thermal dependence of surface tension in most of the DESs analyzed with an average absolute relative deviation of 1.26%. Furthermore, density gradient theory and perturbed-chain statistical associating fluid theory were applied to predict the vapor–liquid surface tension in mixtures of organic compounds with DES. In particular, we have calculated the surface tension in mixtures of ChCl-glycerol and ChCl-lactic acid with water, ethanol, propanol, phenol, acetone, and ethyl acetate without fitting binary interaction parameters. The behavior of density profiles suggests that the surface is enriched with DES components for the DES + water mixtures. In contrast, it is enriched with diluent for the other ternary systems (ethanol, isopropanol, phenol, acetone, and ethyl acetate).

Protic Ionic Liquid Cation Alkyl Chain Length Effect on Lysozyme Structure.

Solvents that stabilize protein structures can improve and expand their biochemical applications, particularly with the growing interest in biocatalytic-based processes. Aiming to select novel solvents for protein stabilization, we explored the effect of alkylammonium nitrate protic ionic liquids (PILs)-water mixtures with increasing cation alkyl chain length on lysozyme conformational stability. Four PILs were studied, that is, ethylammonium nitrate (EAN), butylammonium nitrate (BAN), hexylammonium nitrate (HAN), and octylammonium nitrate (OAN). The surface tension, viscosity, and density of PIL-water mixtures at low to high concentrations were firstly determined, which showed that an increasing cation alkyl chain length caused a decrease in the surface tension and density as well as an increase in viscosity for all PIL solutions. Small-angle X-ray scattering (SAXS) was used to investigate the liquid nanostructure of the PIL solutions, as well as the overall size, conformational flexibility and changes to lysozyme structure. The concentrated PILs with longer alkyl chain lengths, i.e., over 10 mol% butyl-, 5 mol% hexyl- and 1 mol% octylammonium cations, possessed liquid nanostructures. This detrimentally interfered with solvent subtraction, and the more structured PIL solutions prevented quantitative SAXS analysis of lysozyme structure. The radius of gyration (Rg) of lysozyme in the less structured aqueous PIL solutions showed little change with up to 10 mol% of PIL. Kratky plots, SREFLEX models, and FTIR data showed that the protein conformation was maintained at a low PIL concentration of 1 mol% and lower when compared with the buffer solution. However, 50 mol% EAN and 5 mol% HAN significantly increased the Rg of lysozyme, indicating unfolding and aggregation of lysozyme. The hydrophobic interaction and liquid nanostructure resulting from the increased cation alkyl chain length in HAN likely becomes critical. The impact of HAN and OAN, particularly at high concentrations, on lysozyme structure was further revealed by FTIR. This work highlights the negative effect of a long alkyl chain length and high concentration of PILs on lysozyme structural stability.

Surface tension of binary mixtures of benzene + propionic acid and butanoic acid between 298.15 K and 318.15 K: Measurement and modeling

Experimental measurement of the surface tension of benzene + propanoic acid and benzene + butanoic acid has been carried out in the temperature range of 298.15 K to 318.15 K and atmospheric pressure. 170 new experimental points of surface tension have been obtained. Three theoretical models, i.e., Linear gradient theory (LGT), Shereshefsky model (SM), and the extended Langmuir model (LM), were used to modeling the surface tension and adsorption phenomenon of these binary mixtures. The three models correlated the surface tension of the benzene + carboxylic acid mixtures, and the average percent deviation was, 0.04% for LGT, 0.08% for SM, and 0.05% for LM. The Helmholtz density term and the liquid and vapor densities required in computing density with LGT were obtained with perturbed chain-statistical associating fluid theory equation of state (PC-SAFT EOS). Based on SM, the standard Gibbs energy of adsorption and the free energy change in the surface region were calculated. The free energy change was used to obtain the excess number of molecular layers in the surface region. The required parameters of the LM were adjusted, the standard Gibbs energy of adsorption was calculated, and negative deviations from ideality were determined. Also mole fractions of solute 0at surface were calculated by using LM. Additionally, by using surface tensions at different temperatures, specific surface enthalpy and specific surface entropy were calculated for (benzene + carboxylic acid) mixtures.

Effect of the degree of hydrogenation on the viscosity, surface tension, and density of the liquid organic hydrogen carrier system based on diphenylmethane

For the efficient design of hydrogenation and dehydrogenation processes, a comprehensive database for the viscosity, surface tension, and density of mixtures of the diphenylmethane-based liquid organic hydrogen carrier system and the pure intermediate cyclohexylphenylmethane measured by complementary optical and conventional methods and calculated by molecular dynamics simulations at process-relevant temperatures up to 623 K is presented. The simulations employ self-developed force fields including a new one for cyclohexylphenylmethane and reveal surface enrichment and orientation effects influencing the surface tension. Relatively simple correlation and prediction approaches yield accurate representations as function of temperature and degree of hydrogenation (DoH) of the mixtures with average absolute relative deviations (AARD) of 0.07% for the density and 2.9% for the surface tension. Application of the extended hard-sphere theory considering the presented accurate density data allows capturing the highly nonlinear DoH-dependent behavior of the dynamic viscosity with an AARD of 2.9%.

Surface Activity and Efficiency of Cat-Anionic Surfactant Mixtures.

The surface activity of surfactant mixtures is critically analyzed. Cat-anionic systems, in which two ionic species are mixed in non-stoichiometric ratios, are considered. With respect to the solution behavior, where a substantial decrease of cmc is met compared to the pure components, a moderate effect on surface tension, γ, occurs. Compared to the pure species, the decrease of surface tension for such mixtures is not significant, and no clear dependence on the mole fraction anionic/cationic is met. The surface tension is grossly constant in the whole concentration range. Conversely, the interaction parameter for surfaces, β surf (calculated by the regular solution theory), is more negative than that for micelle formation, β mic . This fact suggests that the desolvation of polar heads of the two species at interfaces is largely different. Very presumably, the underlying rationale finds origin in the sizes and solvation of both polar head groups.

Surface tension and parachor for a new low-GWP refrigerant R1123/R32/R1234yf and its constituent binary pairs

Trifluoroethene R1123 is expected to be a low GWP refrigerant; however, it needs to be mixed with other stable refrigerants to avoid a disproportional reaction. This paper delivers one of the essential thermophysical properties surface tension for a low-GWP refrigerant mixture R1123/R32/1234yf measured by the differential capillary rise method in the temperature range from 225 to 345 K. The propagated uncertainty in surface tension with a 95% confidence level was typically 0.15 mNm−1. From the measured surface tension and calculated saturation densities, the parachor of R32 and R1123 were determined to be 91.6 and 123.3, respectively. The parachor of R1234yf was slightly dependent on a temperature, T, as 181.44−0.0319T. The variation in the surface tension of binary pairs against the composition was predicted by the correlation proposed by Di Nicola et al. (2018) and the parachor method with sufficient accuracy. Furthermore, the surface tension of ternary mixture R1123/R32/1234yf at compositions of 60/22/18 mass% and 22/70/08 mass% was also predicted by the parachor method with sufficient accuracy. Nevertheless, a slight deviation was confirmed at temperatures below 260 K. The prediction would be improved with subsequent studies in phase equilibrium. (191 words).

Surface tension of liquids and binary mixtures from molecular dynamics simulations

In this work we assess and extend strategies for calculating surface tension of complex liquids from molecular dynamics simulations: the mechanical route and the instantaneous liquid interface (ILI) approach. The former employs the connection between stress tensor and surface tension, whereas the latter involves computation of instantaneous density field. Whereas the mechanical route is general, the ILI method involves system-dependent parameters restricting its original application to liquid water only. Here we generalize the approach to complex molecular liquids using atomic van der Waals radii. The performance of the approaches is evaluated on two liquid systems: acetonitrile and water–methanol mixture. In addition, we compare the effect of the computational models for interaction potentials based on semi-empirical electronic structure theory and classical force fields on the estimate of the surface tension within both stress tensor and ILI approaches.

Foaming of Binary Mixtures: Link with the Nonlinear Behavior of Surface Tension in Asymmetric Mixtures.

The lifetimes of single bubbles or foams that are formed in mixtures of liquids can be several orders of magnitude larger than the ones formed in pure liquids. We recently demonstrated that this enhanced stability results from differences between bulk and interfacial concentrations in the mixture, which induce a thickness dependence of the surface tension in liquid films, and thus a stabilizing Marangoni effect. Concentration differences may be associated with nonlinear variations of surface tension with composition and we further investigate their link with foamability of binary mixtures. We show that, for asymmetric binary mixtures, that is, made of molecules of very different sizes, strong nonlinearities in surface tension can be measured, that are associated with large foam lifetimes. When the molecules that occupy the largest surface areas have the smallest surface tension, the surface tension of the mixture varies sublinearly with composition, reflecting an enrichment in this species at the interface with air, as classically reported in the literature. In contrast, when they exhibit the largest surface tension, superlinear variations of surface tension are observed, despite a similar enrichment. We discuss these variations in light of a simple thermodynamic model for ideal mixtures and we demonstrate why foam stability is enhanced for both sublinear and superlinear surface tension variations, thus, shedding new light on foamability without added surfactants.

Examination of the Butler Equation for the Surface Tension of Liquid Mixtures.

The classical Butler equation used to describe surface tension and the surface composition of liquid mixtures is revisited. A straightforward derivation is presented, separating basic chemical thermodynamics and assumptions proper to Butler’s model. This model is shown to conceal an approximation not recognized by other researchers. The shortcoming identified consists of not allowing surface standard values to vary with surface tension by virtue of the changing composition. A more rigorous equation is derived and shown to yield the Butler equation in case of incompressible surface phases. It is concluded that the Butler equation slightly overestimates ideal surface tensions. Butler’s surface-phase concentrations of the surface-active component are also slightly overestimated in the surface-active component dilute range, being just underestimated at higher concentrations. Despite this, Butler’s model stands as a very good standard due to its versatility.

Surface thermodynamics of 2-chloroethanol with 2-dimethylaminoethanol and 2-diethylaminoethanol at different temperatures

ABSTRACT The surface tension of binary mixtures of 2-chloroethanol with 2-dimethylaminoethanol (DMAE) and 2-diethylaminoethanol (DEAE) was measured over the entire composition range at the temperatures 293.15 K to 313.15 K and atmospheric pressure. The excess values of surface tension were correlated with the Redlich-Kister polynomial equation. The experimental surface tension was correlated with five different theoretical models. The Hilderbrand and Scott theories for ideal solutions (HSIS) and their extensions of Guggenheim’s equation (HSEG), Volume Fraction Statistics, Sudgen method and modified New Parachor method were applied to determine the values of surface tension in the binary solvent systems. The surface tension data were further used to determine the surface thermodynamic properties such as surface entropy (SS) and surface enthalpy (HS) per unit surface area. The results have brought about some useful information on the extent of molecular interactions between the unlike molecules occurring at the surface and bulk.

Surface tension of binary and ternary polymer solutions: Experimental data of poly(vinyl acetate), poly(vinyl alcohol) and polyethylene glycol solutions and mixing rule evaluation over the entire concentration range

In order to assess the driving forces of Marangoni instabilities in drying polymer solution films, surface tension data over a wide concentration are necessary. While experimental data and mixing rule equations for the surface tension of liquid-liquid mixtures are readily available, data for polymer solutions are scarce. The aim of this work is to report surface tension data of methanol-toluene-poly(vinyl acetate), methanol-water-polyethylene glycol and water-poly(vinyl alcohol) solutions as well as to evaluate the applicability of available liquid-liquid mixing rule equations on polymer solutions despite an inevitable data gap at low solvent concentrations due to viscosity increase and solidification. The fit quality was assessed by calculating the averaged deviation as well as by manually checking for implausible curve shapes in the respective concentration data gaps. Several available but slightly modified equations are well equipped to describe the concentration and temperature dependent surface tension of the material systems under investigation. Recommendations are given for binary and ternary solutions.

Adsorption Properties of Hydrocarbon and Fluorocarbon Surfactants Ternary Mixture at the Water-Air Interface.

Measurements were made of the surface tension of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycols) having 10 oxyethylene groups in the molecule (Triton X-100, TX100) and cetyltrimethylammonium bromide (CTAB) with Zonyl FSN-100 (FC6EO14, FC1) as well as with Zonyl FSO-100 (FC5EO10, FC2) ternary mixtures. The obtained results were compared to those provided by the Fainerman and Miller equation and to the values of the solution surface tension calculated, based on the contribution of a particular surfactant in the mixture to the reduction of water surface tension. The changes of the aqueous solution ternary surfactants mixture surface tension at the constant concentration of TX100 and CTAB mixture at which the water surface tension was reduced to 60 and 50 mN/m as a function of fluorocarbon surfactant concentration, were considered with regard to the composition of the mixed monolayer at the water-air interface. Next, this composition was applied for the calculation of the concentration of the particular surfactants in the monolayer using the Frumkin equation. On the other hand, the Gibbs surface excess concentration was determined only for the fluorocarbon surfactants. The tendency of the particular surfactants to adsorb at the water-air interface was discussed, based on the Gibbs standard free energy of adsorption which was determined using different methods. This energy was also deduced, based on the surfactant tail surface tension and tail-water interface tension.

Recommended Correlations for the Surface Tension of n-Alkanes

In previous papers, specific correlations were proposed to reproduce the surface tension values selected for several families of fluids and for wide ranges of temperatures. In this paper, the surface tension of n-alkanes is considered. For that, the data available in DIPPR and DETHERM databases and in Wohlfarth and Wohlfarth [“Surface tension of pure liquids and binary liquid mixtures,” in Landolt-Börnstein, New Series Group IV Physical Chemistry Vol. 16, edited by M. D. Lechner (Springer-Verlag, Berlin, 1997)] and its updated supplements (2008 and 2016) have been compiled. In most cases, a significant number of new data have been added, which were published elsewhere during the last few years and that were not included in the previously mentioned sources. All the data and values available for each fluid have been carefully screened and subsequently fitted to the Guggenheim–Katayama model, which includes two to six adjustable coefficients for each fluid. As a result, recommended correlations for 33 n-alkanes are proposed, providing absolute deviations below 1.65 mN/m and mean absolute percentage deviations below 2.1%.

Unexpected acceleration of Ultrasonic-Assisted iodide dosimetry in the catalytic presence of ionic liquids

This study investigates the potential of using small amounts of ionic liquids (IL) to enhance ultrasound-assisted extraction of lipids content from green microalgae. Three imidazolium-based ILs (butyl, octyl and dodecyl), each of them with two anions (bromide and acetate) were tested as additives. Viscosity and surface tension of the ILs aqueous mixtures were analyzed to determine the influence of ILs’ anions and alkyl chain length, whereas KI dosimetry experiments were used as an indicator of radicals formation. A key finding suggests that the small addition of ILs improves the ultrasonication either by enhancing the viscosity and reducing the water surface tension, leading to a more powerful acoustic cavitation process or by increasing HO° production likely to oxidize the microalgae cells membranes, and consequently disrupting them on a more efficient manner. KI dosimetry also revealed that long ILs alkyl chain is detrimental. This experimental observation is confirmed thus strengthened as the yield of extracted lipids from green microalgae has shown an incremental trend when the IL concentration also increased. These hypotheses are currently under investigation to spot detailed impact of ILs on cavitation process.

Surface tensions of biodiesel blends with pentanol and octanol isomers at different conditions: measurement and new correlation

Surface tension is an important biodiesel property, its calculation and prediction are fundamental because high values of surface tension significantly difficult proper atomization, and it can cause a poor engine performance. Surface tensions have been measured for binary liquid blends of pentan-1-ol, pentan-2-ol, 2-methylbutan-1-ol, octan-1-ol, octan-2-ol and 2-ethylhexan-1-ol with biodiesel using a Du Noüy ring tensiometer from (288.15 to 338.15) K at 0.1 MPa over the whole composition range. The measured surface tension data for the pure components shows a good agreement for the six alcohols when it is compared with reported values in the literature, showing an average absolute percentage deviation of 0.93%. Surface tension deviations show positive deviations from the average mole fraction of the pure components and they are correlated using the Redlich-Kister equation over the whole concentration range. Surface entropy and surface enthalpy have been estimated from experimental surface tension values of biodiesel mixtures. A new equation has been developed to correlate the surface tension of biodiesel + alcohols mixtures considering the effects of both temperature and mole fraction. This equation is based upon a quadratic mixing rule for the Gibbs free energy. Our model demonstrates to correlate the surface tension of biodiesel mixtures with an average absolute percentage deviation of 0.4%. The correlative capability of the proposed model is compared with Li et al., Fu et al., Myers and Scott, Wang-Chen, Hoke and Patton, and Jouyban et al. equations.

Surface tension of binary mixtures containing environmentally friendly ionic liquids: Insights from artificial intelligence

The surface tension (ST) of ionic liquids (ILs) and their accompanying mixtures allows engineers to accurately arrange new processes on the industrial scale. Without any doubt, experimental methods for the specification of the ST of every supposable IL and its mixtures with other compounds would be an arduous job. Also, experimental measurements are effortful and prohibitive; thus, a precise estimation of the property via a dependable method would be greatly desirable. For doing this task, a new modeling method according to artificial neural network (ANN) disciplined by four optimization algorithms, namely teaching–learning-based optimization (TLBO), particle swarm optimization (PSO), genetic algorithm (GA) and imperialist competitive algorithm (ICA), has been suggested to estimate ST of the binary ILs mixtures. For training and testing the applied network, a set of 748 data points of binary ST of IL systems within the temperature range of 283.1–348.15 K was utilized. Furthermore, an outlier analysis was used to discover doubtful data points. Gained values of MSE & R2 were 0.0000007 and 0.993, 0.0000002 and 0.998, 0.0000004 and 0.996 and 0.0000006 and 0.994 for the ICA-ANN, TLBO-ANN, PSO-ANN and GA-ANN, respectively. Results demonstrated that the experimental data and predicted values of the TLBO-ANN model for such target are wholly matched.