Experimental Surface Tension Data Research Articles

An experimental-computational study on thermodynamic properties and intermolecular interactions of binary mixtures composed of quaternary ammonium salts-based deep eutectic solvents and [ETN] or [ACN]

To deep understand the thermodynamic properties and intermolecular interactions of quaternary ammonium salts-based deep eutectic solvents (DESs), two novel DESs systems ([TPAB]:[MA] and [TBAB]:[MA]) were synthesized using tetrapropylammonium bromide ([TPAB]) or tetrabutylammonium bromide ([TBAB]) as hydrogen bond acceptor (HBA) and malonic acid ([MA]) as hydrogen bond donor (HBD). Then, the ethanol (ETN) and acetonitrile (ACN) were used to prepare four DESs + solvent mixtures. Based on experimental data of density and surface tension of these four binary mixtures, the thermodynamic parameters such as apparent molar volume (Vϕ), excess molar volume (VE), limiting apparent molar expansibility (E0ϕ), molar surface entropy (s), molar surface Gibbs energy (gs), and molar surface enthalpy (h) were calculated. At the same temperature, the calculated VE values of binary mixtures were arranged in the following sequence: [TBAB]:[MA] + [ETN] > [TPAB]:[MA] + [ETN] > [TPAB]:[MA] + [ACN] > [TBAB]:[MA] + [ACN]. Based on the radial distribution functions (RDFs) theory, this observed phenomenon was attributed to the enhanced interaction between HBA and [ETN] in the DESs + [ETN] as compared to the interaction between HBA and [ACN] in the DESs + [ACN]. The predicted surface tension values (γ(pre)) of the four binary mixtures were calculated and highly correlated with the experimental surface tension values (γ(exp)). Moreover, the Br1 atom in [TPAB], the Br2 atom in [TBAB], and the H9 atom in [MA] were selected as reference sites. The interaction strength sequence between HBD and HBA was investigated using RDFs as follows: [TBAB]:[MA] + [ACN] > [TPAB]:[MA] + [ACN] > [TBAB]:[MA] + [ETN] > [TPAB]:[MA] + [ETN]. This study can provide an important theoretical support for further utilization of quaternary ammonium salts-based DESs.

Molecular dynamics study on the anomalous behavior of phase transition heats of alcohols at vapor–liquid interface

The surface adsorptions of methanol, ethanol and 1-propanol liquids at vapor–liquid interface are investigated with the surface adsorption theory and molecular dynamics simulations (MD). The surface layer thicknesses of these three liquids calculated with MD increase with temperature. It is found that the thickness of the surface layer becomes smaller as the intermolecular interaction becomes stronger. The heat of phase transition from the bulk to surface determined with the experimental surface tension data decreases from methanol to ethanol and increases from ethanol to propanol. This anomalous behavior is different from the usual one of the phase transition heats which changes monotonously with the alkyl chain length in literature. Since the reversible phase transition heat is equal to T(Ss-Sα), the entropy changes of these three liquids are calculated with MD simulations and are in agreement with the variation trend of phase transition heats determined from the experimental data. This is a qualitative confirmation of our surface adsorption theory from the viewpoint of the molecular dynamic simulations.

Impact of critical point restriction on the calculation of surface tension of organic acids using group contribution models

This manuscript reports the calculation of surface tension of organic acids using new group contribution models. These models were obtained from the Jasper equation and the van der Waals principle of corresponding states. A special analysis was performed to determine the impact of incorporating the critical point restriction on the performance of tested group contribution models. This restriction was incorporated via a penalty term on the objective function used in the group contribution determination, and using the reduced temperature as the input model variable. A total of 885 experimental surface tension data points for 78 organic acids (including aliphatic, aromatic, dicarboxylic, and polyfunctional acids) were used to compare the performance of these group contribution models. The results showed that tested models calculated the surface tension of polyfunctional and aliphatic organic acids with modeling errors lower than 5%. However, the calculation of surface tension of aromatic and dicarboxylic acids was challenging for all tested models. The incorporation of critical point restriction of surface tension as a penalty term in the data processing stage did not improve the performance of tested group contribution models. Group contribution models that used the reduced temperature as an input variable showed the best performance for the calculation of the surface tension of these organic compounds.

Volumetric Properties, Molar Surface Gibbs Energy, and Its Application of Binary Systems Containing Ether-Group Functionalized Ionic Liquid with Monohydric Alcohols

Ether-group functionalized ionic liquid N-(2-methoxyethyl)-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [C1OC2pyrr][NTf2], was synthesized and characterized by 1H NMR, 13C NMR, and TGA. The density and surface tension of binary mixtures including [C1OC2pyrr][NTf2] and monohydric alcohols were measured over the entire range of mole fractions in different temperatures. Based on the experimental data of density and surface tension, the volumetric and surface properties of [C1OC2pyrr][NTf2] and its binary mixtures were obtained, and Vm, αp, and VE were explored. The effects of temperature and composition on these properties were investigated, and the excess molar volume of two binary mixtures was well fitted by the Redlick-Kister equation. The molar surface Gibbs energy (gs) of [C1OC2pyrr][NTf2] and its binary mixtures was calculated, and the traditional Eötvös equation was modified; moreover, all parameters had a clear physical meaning. Finally, based on gs, the surface tension of [C1OC2pyrr][NTf2] and its binary mixtures was estimated, and it is in good agreement with experimental values.

Surface tension models for binary aqueous solutions: a review and intercomparison.

The liquid-air surface tension of aqueous solutions is a fundamental quantity in multi-phase thermodynamics and fluid dynamics and thus relevant in many scientific and engineering fields. Various models have been proposed for its quantitative description. This Perspective gives an overview of the most popular models and their ability to reproduce experimental data of ten binary aqueous solutions of electrolytes and organic molecules chosen to be representative of different solute types. In addition, we propose a new model which reproduces sigmoidal curve shapes (Sigmoid model) to empirically fit experimental surface tension data. The surface tension of weakly surface-active substances is well reproduced by all models. In contrast, only few models successfully model the surface tension of aqueous solutions with strongly surface-active substances. For substances with a solubility limit, usually no experimental data is available for the surface tension of supersaturated solutions and the pure liquid solute. We discuss ways in which these can be estimated and emphasize the need for further research. The newly developed Sigmoid model best reproduces the surface tension of all tested solutions and can be recommended as a model for a broad range of binary mixtures and over the entire concentration range.

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%.

Application of surface tension in the design of novel Sn-Ag-Cu-based solders

Surface tension is closely related to the wettability of solders, which is a crucial property for the design of Pb-free solders. However, the experimental surface tension data are scarce, especially for the multicomponent systems. In this paper, the surface tension of Sn-Ag-Cu (SAC) based ternary, quaternary and quinary alloys are predicted by various models and verified by experimental data. The calculated results by General Solution model (GSM) combined with binary experimental data are in best agreements with experimental values for most systems. For the systems without enough binary experimental data, GSM model combined with binary Butler equation can also achieve reliable results, which has been applied for predicting the surface tension of SAC305-based quaternary and quinary alloys to guide the design of novel Pb-free solders.

Surface tension, viscosity and electrical conductivity characteristics of new ether-functionalized ionic liquids

1-(2-Ethoxyethyl)-3-methylimidazolium acetic acid ([C2OC2mim][OAc]) and 1-(2-ethoxyethyl)-3-methylimidazolium lactic acid ([C2OC2mim][Lac]) ether-functionalized ionic liquids (ILs) were prepared. In terms of the standard addition method, the experimental data of density, surface tension, refractive index, viscosity and electrical conductivity of two pure ILs were obtained. Using the definition of the molar surface Gibbs energy with Lorentz-Lorenz empirical equation, the surface tensions of ether-functionalized ILs were estimated, and their predicted values were in good agreement with the experimental values. According to the Vogel-Fulcher-Tamman (VFT) equation, the variation tendency between viscosity (or electrical conductivity) and temperature of [C2OC2mim][OAc] and [C2OC2mim][Lac] was studied. The variation trend of the viscosity was opposite to electrical conductivity. Namely, the viscosity gradually decreased and electrical conductivity gradually increased with increasing temperature. The results indicated that VFT equation had an enormous application range for fitting the viscosity and electrical conductivity of ether-functionalized ILs. The activation energies of [C2OC2mim][OAc] and [C2OC2mim][Lac] were estimated by Arrhenius empirical equation. The calculated results indicated that [C2OC2mim][Lac] (Eη means the activation energy, Eη = 41.24 kJ·mol−1) was larger than [C2OC2mim][OAc] (Eη = 33.57 kJ·mol−1). This result may be related to physical size or stronger interactions.

Semi-empirical linear correlation between surface tension and thermodynamics properties of liquids and vapours

Abstract There are three interpretations of surface tension in the scientific literature based on phenomenological, thermodynamics and molecular dynamics arguments. The equivalence between phenomenological and thermodynamics interpretations is well known, but there is no explicit model to connect them with the principles of molecular dynamics. In molecular dynamics the concept of pressure is divided into two independent contributions referred as kinetic and cohesive. In this study a semi-empirical model of surface tension is proposed based on unbalanced intermolecular forces at the interphases. The model incorporates elements from the previous three interpretations and recognizes the existence of kinetic and cohesive contributions to pressure. Published experimental data of surface tension is used to determine the two model empirical parameters representing the thickness of interphases and average intermolecular forces. The results show that the proposed model correctly predicts a linear relationship between surface tension and thermodynamics properties of liquids and vapours in equilibrium.

100th Anniversary of Macromolecular Science Viewpoint: The Role of Hydrophobicity in Polymer Phenomena.

The seemingly simple notion of the hydrophobic effect can be viewed from multiple angles involving theory, simulation, and experiments. This viewpoint examines five attributes of predictive models to enhance synthetic efforts as well as experimental methods to quantify hydrophobicity. In addition, we compare existing predictive models against experimental data for polymer surface tension, lower critical solution temperature, solution self-assembly morphology, and degradation behavior. Key conclusions suggest that both the Hildebrand solubility parameters (HSPs) and surface area-normalized Log P (Log P SA–1) values provide unique and complementary insights into polymer phenomena. In particular, HSPs appear to better describe bulk polymer phenomena for thermoplastics such as surface tension, while Log P SA–1 values are well-suited for describing and predicting the behavior of polymers in solution.

Micellization thermodynamic behavior of gemini cationic surfactants. Modeling its adsorption at air/water interface

Abstract Self-assembly structures of gemini surfactants are characterized, among others, for their low CMC. This characteristic could be due to great hydrophobic parts in their molecular structures. That availability could imply great stability of self-assembly structures or monolayers absorbed in an interface. The micellization behavior of two cationic gemini surfactants, α,ω-bis(S-alkyl dimethylammonium) alkane bromides, was studied by a modelization of dynamic surface tension (DST) experimental data and isothermal titration calorimetry (ITC) measurements. The adsorption data at the air/water interface was taken through the analysis of the profile changes of a pendant drop. The thermodynamic characterization of the micellization process of the gemini surfactants was carried out using ITC. A model based on the Frumkin adsorption isotherm and the Ward-Tordai diffusion equation was developed to obtain the characteristic parameters of the adsorption without the need of using the Gibbs adsorption equation. Positive values of lateral interaction show good stability of the adsorbed monolayer. The ITC data were analyzed following a novel protocol based on the identification of the different energetic contributions and regimens observed in the titration enthalpograms from demicellization processes. The presence of exothermic peaks would explain the low values of CMC.

An insight into thermodynamic and association behaviours of cocamidopropyl betaine (CAPB) surfactant in water and water–alcohol mixed media

This article presents new experimental data about the conductivity and surface of Cocamidopropyl Betaine (CAPB) surfactant in pure H2O and organic–H2O mixed solvent (methanol, MeOH; ethanol, EtOH and glycerol, GlyOH) media containing various mole fractions of alcohols over the temperature range 298.15 to 313.15 K, in steps of 5 K using conductometric and surface tension measurements. The experimental data for conductivity and surface tension have been used in order to determine the critical micelle concentration (CMC). It has been observed that the CMC increases with increasing temperature and proportion of alcohol. Moreover, the association constant ( $$K_{a}$$ ) of CAPB was also determined, depending on the conductivity data, using the Shedlowsky equation. The study showed that, as the temperature and alcohol ratio increased, the association constant of CAPB decreased. In addition, it was found that the CMC increased with MeOH > EtOH > GlyOH and the association behaviour was observed to be spontaneous. The thermodynamics behaviour of (CAPB) surfactant have been thoroughly assessed from the temperature dependence of the micellization and association constants. In all media studied, densities and refractive indices of CAPB were also measured under atmospheric pressure, in the solvents used at T = (298.15 K). The molal volume was estimated based on the density data and some additionally parameters such as molar refraction and the polarizability were also estimated and discussed depending on the refractive index values. These parameters have been utilized to comprehend the association and solvation behaviour of the CAPB surfactant.

Surface and transport properties of liquid Bi–Sn alloys

The new Bi–Sn surface tension experimental data have been obtained by the pinned drop method for temperatures ranging from 623 to 1123 K and were subsequently compared with the model predicted values as well as with the literature data. Taking into account endothermic mixing in liquid Bi–Sn alloys, the surface properties (surface tension and surface segregation) were described by the Quasi-Chemical Approximation (QCA) for regular solution and the Self Association Model (SAM) aiming to estimate the effects of demixing on these properties. In addition, the transport and structural properties of Bi–Sn melts were analysed by theoretical models developed in the framework of statistical mechanics in conjunction with the Quasi-Lattice Theory (QLT) and Faber-Ziman Theory. The abovementioned properties are involved in the development of complex solder materials based on the Bi–Sn system.

Correlation and prediction of surface tension of highly non-ideal hydrous binary mixtures using artificial neural network

Prediction of surface tension of highly non-ideal binary aqueous–organic mixtures is crucial for interpreting the interaction between the molecules. In this regard, a multi-layer perceptron (MLP) artificial neural network (ANN) model is developed to predict the binary aqueous–organic surface tension as a function of mixture composition and temperature while the organic compounds are very dissimilar in size and type. To correlate the binary surface tension, gathered experimental surface tension data consisted of 30 binary mixtures containing 2271 data points in the wide temperature range of 273–471.15 K are randomly divided into three different subsets namely training (70 % of total data), validation (15 % of total data) and testing (15 % of total data) subsets. Different input variables are examined and the number of hidden neurons is optimized. The obtained results revealed that it is possible to correlate the binary surface tension with the best MLP network with 27 neurons in the hidden layer and inputs variables of temperature, mole fraction, molecular weight and critical pressure of non-water component with the average absolute relative deviation (AARD %) of lower than 1.43 %. Comparison of accuracy of the MLP model with several common models such as Jouyban-Acree model, Wilson equation, Paquette and Rasmussen areas and several equations of state including SRK, PR and CPA revealed more accuracy of the proposed MLP based model.

Experimental Investigation of the Thermophysical Properties of the Bio-Aviation Fuel Surrogates: Binary and Ternary Mixtures of n-Dodecane, Methyl Butyrate, and Methyl Decanoate

For the investigation of injection characteristics of fuels in the internal combustion engines or turbines, thermophysical properties like liquid kinematic viscosity, surface tension, density, and refractive index are crucial and necessary. In this work, the liquid kinematic viscosity and surface tension were measured by surface light scattering (SLS) for the binary and ternary mixtures of n-dodecane with methyl butyrate and methyl decanoate, respectively, in the temperature ranges from (308.15 to 413.15) K for the mixtures and (298.15 to 423.15) K for methyl butyrate. Additionally, the liquid density was determined by a U-tube densimeter from (293.15 to 423.15) K, and refractive index was measured from (278.15 and 358.15) K. Furthermore, the experimental data of surface tension and kinematic viscosity for the mixtures were correlated with two proposed equations against the temperatures and mole fractions. The density and refractive index data were correlated by polynomial functions. This work provides essential data and correlation models for the crucial thermophysical properties of the binary model fuels for the bio-aviation kerosene in connection with the investigation of the fuel injection and combustion system.

Assessment of a Simplified Correlation Between Wettability Measurement and Dispersion/Coagulation Potency of Oxide Particles in Ferrous Alloy Melt

This article seeks to demonstrate a direct and simplified correlation between the measurement of the wettability and the agglomeration potency of the inclusion particles in liquid ferrous alloy. The established methodology has been validated by the agreement between the calculated coagulation coefficient of Al2O3 particles and the experimental data in the open literature. Subsequently, the coagulation coefficient of Al2O3, MgO, and Ti2O3 particles in ferrous alloy melts was evaluated quantitatively by the proposed method using the actual experimental data of contact angle and surface tension. Meanwhile, the effect of the matrix composition has been investigated by comparing the Hamaker constant and coagulation coefficient between Ti2O3/pure iron and Ti2O3/low-carbon steel systems. It is noted that the change of coagulation coefficient associated with the contact angle is caused by the formation of a new phase at the oxide/metal interface at the high temperature. The present work aims to provide a deep understanding of the connection between inclusion motion behavior in the liquid alloy and the high temperature interfacial phenomenon.

Temperature and oxygen adsorption coupling effects upon the surface tension of liquid metals

An accurate knowledge of the surface tension of liquid metals is critical for many theoretical and practical applications, especially in the current context of emerging growth of nanotechnology. The surface tension and its temperature dependence are drastically influenced by the level of impurities in the metal such as oxygen, sulphur or carbon. For this reason, experimental surface tension data of metals reported in literature are scattered. Strictly speaking, when referring to the surface tension of liquid metals, both variables temperature and oxygen content must be specified. There exists no clear formalism describing the coupling effect temperature and the oxygen content upon the surface tension of liquid metals. The aim of this work is to fill this gap. A thermodynamically self-consistent formulation for the surface tension of liquid metals and semiconductors as a function of temperature and oxygen content is established. According to the proposed formalism, a reliable expression for the surface tension of pure and oxygen saturated metals is then derived. The proposed model is found to be in good agreement with available experimental data, showing a good predictive capability. Aluminium is chosen and thoroughly evaluated as a case study, due to its very high sensitivity to oxygen level. Its surface tension is explicitly formulated as a function of temperature and oxygen content.

A versatile multicomponent database for the surface tension of liquid metals

Experimental surface tension data for many binary, ternary and higher order metallic systems is unfortunately currently unavailable in the literature. This could be detrimental in several practical and industrial applications. Consequently, having a theoretical model with a good predictive capability is highly desirable. In general, the surface tension of metallic alloys is predicted via the well-established Butler model. This model assumes a linear relationship between the excess Gibbs energy in the Bulk and on the surface. For many systems, this assumption is not valid, especially for systems based on elements with different bulk electronic structures, for which the Butler model fails to predict the composition dependence of the surface tension (As demonstrated in this work, the Butler model is accurate only for about 65% of metallic system for which experimental data is available). The aim of this paper is to propose an alternative to the Butler model to represent accurately the surface tension multi component liquid metals. The proposed model is an extension of the Guggenheim model of ideal solutions to take into account the difference of electronic structures between elements of a solution. The model is compared with the 36 binary and 7 ternary metallic alloys for which experimental data is available. It is shown that the accuracy of the model is higher than 95%. On that basis, the composition dependence of the surface tension of many other binary alloys for which experimental data is not available is predicted. The extension of the model to ternary and higher order systems is proposed without introducing any new parameters, i.e. by considering only the binary parameters. It is shown that the extended model provides also an accurate prediction of the surface tension for ternary metal.

Measurement and correlation studies of phase equilibria and thermophysical properties of 4-tert-butylbenzaldehyde

This study reports the vapor pressure data and thermophysical properties of 4-tert-butylbenzaldehyde, a fine chemical that is widely used in the manufacturing of fragrances and agricultural chemicals. The saturated vapor pressure was measured at isobaric condition 1.48–33kPa using a modified Swietoslawski-type ebulliometer and the data was correlated with Antoine and Clark-Glew equation where Antonie equation exhibited less deviation as compared to the Clark-Glew equation. Moreover, the critical properties were estimated based on Joback, Constantinou and Gani and Y. Nannoolal et al. methods. The boiling points computed using Constantinou and Gani method were in close approximation to the Antonie and Clark-Glew equations. The normal boiling point of 4-tert-butylbenzaldehyde was 523.9K with an acentric factor of 0.4. The thermophysical properties i.e., refractive index, density, viscosity and surface tension of 4-tert-butylbenzaldehyde were measured at different temperatures 293.15–328.15K. The density data was correlated with the Rackett equation with group contribution critical parameters. Amidst these contribution methods, Joback was found to exhibit the least relative average deviation (RAD) of 1.29. Further, the viscosity and surface tension were measured using Mansingh Survismeter and viscosity was fitted to the Vogel–Tamman–Fulcher equation with a RAD=1.05 respectively. The surface tension data was predicated using Brock and Bird method with different group contribution critical parameters. Among the investigated models, Nanoolal method-based parameters showed the least RAD. Additionally, the Friccohesity parameter, which deals with frictional and cohesive forces was estimated from the experimental surface tension data. It can be concluded from the present study that none of the prediction methods (group contribution) was able to correctly predict the thermophysical properties of 4-tert-butylbenzaldehyde, hence necessitates the findings of the experimental data.

Experimental studies and artificial neural network modeling of surface tension of aqueous sodium l-prolinate solutions and piperazine blends

Abstract The surface tension study is very crucial for the design of CO2 gas absorption contacting equipment. The significance of the surface tension has been increasing due to its consideration in various technological fields. This property influences the mass transfer and hydrodynamics of gas absorption systems, mainly multiphase systems, in which the interface between gas and liquid exists. Therefore, in this study, surface tension of aqueous solutions of sodium l -prolinate (SP) and piperazine (PZ) blends were measured at ten different temperatures from (298.15 to 343.15) K. The SP mass fractions were 0.10, 0.20, and 0.30; while the mass fractions of PZ were 0.02 and 0.05. The experimental results showed that the surface tension increase with increasing the mass fractions of SP and PZ in aqueous blends, and decrease linearly with rising temperature. The experimental data of surface tension were correlated by two empirical correlations as a function of temperature and mass fractions for estimating the predicted data using the optimized correlation coefficients. Moreover, the modeling of surface tension data was carried out using Artificial Neural Network (ANN) approach. The results obtianed from ANN modeling were compared with applied empirical correlation. It was found that the ANN approach outperformed the empirical correlation used in this study. Besides, a quantitative analysis of variation (ANOVA) was performed in order to determine the significance of data. The surface tension of aqueous SP and SP + PZ was also compared with various conventional solvents.