Huron Vidal Mixing Rule Research Articles

Experimental and thermodynamic modelling of hydrate dissociation conditions for CO[formula omitted] + propane mixtures

The possibility of hydrate formation poses a central issue for Carbon Capture and Storage (CCS) and Enhanced Oil Recovery with Water-Alternating-Gas (EOR/WAG) injection projects. In most of the cases, however, the available fluid for this purpose consists of a CO2-rich stream containing contaminants such as hydrocarbons and permanent gases. As a result, there is a growing interest in evaluating the effect of small impurities concentrations on the phase behaviour of such streams. This work investigates the impact of propane as a promoter in carbon dioxide hydrate formation, covering a concentration range in the feed gas phase between 10 and 69% on mole basis. The study also considers the Lw-LCO2-H region, taking into account liquid and supercritical transportation commonly encountered in CCS projects. Additionally, a procedure to estimate uncertainties in the graphical determination of the dissociation temperature and pressure is discussed. The thermodynamic modelling approach includes three different modifications of cubic equations of state (CEoS): asymmetric mixing rule, advanced Huron-Vidal mixing rule, and cubic-plus-association approach. An alternative procedure based on setting different sets of CO2 Kihara’s parameters when shifting between structures was also used. While satisfactory average temperature deviations were obtained for those equations of state, maximum deviation between calculated and experimental temperatures spanned from 0.5 to 2.5 K, depending on the thermodynamic model.

Bulk and interfacial thermodynamics of ammonia, water and their mixtures

Ammonia is a promising energy carrier for the green transition, but its hygroscopicity and toxicity necessitate in-depth understanding of its interaction with water. This work examines the bulk and interfacial thermodynamics of the ammonia–water system. Parameters for three equations of state are fitted to experimental data and compared to parameters from literature: PC-SAFT, Cubic Plus Association and Peng–Robinson. Peng–Robinson stands out as most accurate for bulk thermodynamics. Introducing a temperature-dependent volume shift for water with Peng–Robinson yields a highly accurate model without introducing problematic inconsistencies, with errors of 0.05% for saturation pressures, and 0.5% for liquid densities. For the mixture, Peng–Robinson with a two-parameter Huron–Vidal mixing rule reproduces measurements mostly within their uncertainties, whereas the standard mixing rules for PC-SAFT and CPA are less accurate. A literature review of surface tension measurements of ammonia–water mixtures reveals that accurate measurements exist only at ambient temperature. We apply density gradient theory and density functional theory based on PC-SAFT, finding that both models fail at reproducing qualitative features of the surface tensions and adsorptions of dilute solutions of aqueous ammonia. Whereas bulk properties are well characterized, understanding and describing the interfacial thermodynamics of the ammonia–water system demands more work both on the experimental and modeling side.

Modelling phase equilibria in the CO2/CH4-H2O-NaCl system using the association equation of state

A new association model, CPA-MHV1, is developed by combining the Soave-Redlich-Kwong (SRK) equation of state (EoS) with the Cubic-Plus-Association (CPA) EoS based on Michelsen's improved Huron-Vidal mixing rule. The model is utilized to investigate the vapor-liquid equilibrium (VLE) of binary mixtures involving methane (CH4), carbon dioxide (CO2), and water (H2O) binary mixtures, as well as ternary mixtures containing sodium chloride (NaCl). CO2 is modeled as a non-associating, non-self-associating (solvation in water) component and as a self-associating component with two, three, or four association sites; furthermore, CH4 is modeled as a non-associating and pseudo-associating component. In the regression of the adjustable parameters, dependence on temperature is considered and the parameters are fitted as functions of temperature. The results demonstrate that the best performance is achieved when solvation between CO2 and H2O is considered, with the average absolute relative deviation (AARD) of 4.50 % in the H2O-rich phase, 5.48 % in the CO2-rich phase, and 3.28 % in NaCl solution. CH4 with pseudo-association scheme has the highest comprehensive prediction performance, and AARD values in H2O-rich phase, CH4-rich phase and NaCl solution are 5.26 %, 5.90 % and 9.19 %, respectively.

Vapor-liquid equilibrium data for binary mixture of 1,1,2,3,3,3-Hexaflfluoro-1-propene (R1216) and trans-1,3,3,3-Tetraflfluoropropene (R1234ze(E)) at temperatures from 275 to 315 K

In this work, the vapor–liquid phase equilibrium (VLE) data of R1234ze(E) and R1216 binary mixtures has been investigated experimentally and theoretically. The VLE data for the binary system of R1234ze(E) + R1216 were measured with a recirculation system at five temperatures range from 275 to 315 K. The experimental results were correlated by Peng-Robinson equation of state combined with Huron-Vidal mixing rule or Wong-Sandler mixing rule and non-random two-liquid activity coefficient model, and van der Waals mixing rule. The calculated values were in well agreement with the experimental results, with the maximum deviations of the pressure and the mole fraction of the vapor phase within 0.87% and 0.016, respectively. The average absolute deviations of the pressure and the mole fraction of the vapor phase between the experimental values and calculated values were 0.35% and 0.005, respectively.

Simulation of multiphase behavior in supercritical CO2–heavy oil–water sludge extraction systems using Cubic-Plus-Association Equation of State

A new methodology was proposed for predicting the multiphase behavior of a supercritical CO2–heavy oil–water–solvent system during supercritical CO2 extraction. The cubic-plus-association equation of state (CPA EoS) was used to model the hydrogen bond association between asphaltene and water and to develop a nine-step characterization method for asphaltene-containing oil. Results showed that the proposed method could represent phase behavior for three equilibrium phases: the vapor phase and high-density and low-density liquid phases. The absolute average relative deviation between the predicted and experimental phase boundary pressures was 3.6–11.8%, smaller than those (7.0–20.8%) calculated using Soave–Redlich–Kwong EoS with Huron–Vidal mixing rules. Moreover, case studies on appropriate extraction conditions showed that the extraction pressure increased with increasing molecular weight and critical pressure of each pseudocomponent. Increasing extraction pressure for H2O-containing systems was beneficial for improving extraction efficiency.

Vapor-liquid equilibrium modeling for binary system of R152a/R1234ze(E)

At present, the environment impact of refrigerants has been given attention. The binary mixture R152a/R1234ze(E) is an environmentally friendly refrigerant, which solves problems of poor cooling performance of the R1234ze(E) cycle and flammability of R152a. In order to obtain its basic thermal and physical parameters, it is necessary to carry out vapor–liquid equilibrium (VLE) research, and the cubic equation of states (EOS) is often used in the calculation of the thermodynamic properties of mixtures. In this paper, the VLE predicted models for R152a/R1234ze(E) in the temperature range of 298.15–328.15 K were constructed using Soave-Redlich-Kwong (SRK), Peng-Robinson (PR) equations of state (EOS) combined with van der Waals (vdW), Huron-Vidal (HV) mixing rules, respectively. The equilibrium pressures and vapor-phase mole fractions of the models were obtained by calculation, and all four models presented an extreme correlation with the experimental data. And it can be concluded that the calculated results of the PR + HV model are closer to the experimental data than those of the other three models, with the average absolute deviation of 0.0027 for vapor-phase mole fraction (AAD(ycal)) and the average absolute relative deviation of 0.243% for equilibrium pressure (AARD(pcal)), which provides a basis for accurately calculating the thermophysical properties of the mixture R152a/R1234ze (E).

Vapor-liquid equilibria calculations for components of natural gas using Huron-Vidal mixing rules

Vapor-liquid equilibria calculations for components of natural gas using Huron-Vidal mixing rules

Prediction of phase equilibria, density, speed of sound and viscosity of 2-alkoxyethanols mixtures: A comparison study between SAFT type EoSs and a modified PR EoS

In this work, a modified Peng-Robinson equation of state with the Huron-Vidal-NRTL mixing rule was used to describe complex polar phase equilibria, density, speed of sound and viscosity at low pressure of alkoxyethanols/alkane, alkoxyethanols/isoalkanes and 2-butoxyethanol/water mixtures. The experimental data is gathered from the literature of a selected alkoxyethanols/alkanes series with the aim of developed generalized expressions for the binary interaction parameters required in the mixing rule model as a function of the RTc/Pc ratio of alkanes. In total 19 mixtures were analyzed (6 used in correlation and 13 mixtures used in prediction processes). For each type of mixture, the generalized expressions were obtained by fitting experimental liquid-liquid equilibria (LLE) data of 3 different mixtures at 100 kPa and to validate them, LLE and vapor-liquid equilibria (VLE) predictions were performed. Adequate results were obtained in all cases. Also, the predictive capabilities of the generalized EoS model have been tested using density, and speed of sound estimations. The overall deviation is below 1.10% for density and 6.84% for speed of sound. Also, the viscosity is correlated and predicted using a simple mixing rule coupled with the generalized EoS model and the absolute deviation is below 3.86%. Finally, two cases of study have been implemented to analyze the possibility of the generalized model to predict other branched-chain alkanes and water systems. The overall results indicated a good agreement with experimental data and proved that the EoS coupled with the Huron-Vidal mixing rule can describe high polar systems and their properties with acceptable and low deviations in comparison to other EoS such as SAFT types or CPA approaches.

Modelling low pressure LLE and VLE of methanol/alkane mixtures with a modified Peng-Robinson EoS and the Huron-Vidal mixing rules

In this work, it is assessed the capabilities and limitations of a simple cubic EoS/GE thermodynamic model to describe the phase equilibria of methanol/alkane mixtures using generalized binary interaction parameters. In first place, the critical properties of the n-alkanes were selected to generalize the parameters of the model by fitting the liquid-liquid equilibria (LLE) of binary mixtures formed by methanol with pentane, heptane and decane respectively. Adequate description of the LLE coexistence curve can be obtained at atmospheric pressure for mixtures with n-alkanes in the 4-10 carbon number range. Also, it is possible to represent the mathematical behavior of the UCST of the methanol alkane series according to literature. Finally, some predictions were made for vapor liquid equilibria (VLE) and vapor-liquid-liquid equilibria (VLLE) conditions at low and high pressure. In general, predictions are unsatisfactory. In some cases, at low pressures, qualitative predictions for the azeotropic behavior can be obtained. In second place, a second set of generalized parameters were obtained by fitting the VLE of binary mixtures formed by methanol with propane, pentane and hexane. Using this new set, the model is capable to reproduce in qualitative way the high-pressure vapor-liquid equilibria of methanol/alkane mixtures between propane and decane. However, for LLE equilibria the results are inadequate from qualitative and quantitative points of view. Based on the results found in this work, it can be established that the selected model is not capable to describe simultaneously the VLE and LLE of methanol/alkane type mixtures reasonably with a single set of binary interaction parameters.

Kinetic modeling and experimental investigations of dry reforming of methanol over a Cr-Mo-Mn/SiO2 catalyst

To derive a kinetic model for dry reforming of methanol, the experimental investigations were accomplished at vast working conditions (i.e., temperature: 500 °C–900 °C and CO2/CH3OH ratio (C/M) of 1–2.5) on Cr-Mo-Mn/SiO2 catalyst. The kinetic model developed based on the Langmuir–Hinshelwood (LH) approach and mechanism contained three reversible reactions on three types of active sites. The results of the statistical analysis presented that kinetic model parameters were statistically significant. The error of the suggested kinetic model was 9.87% using equation state (EoS) of Soave–Redlich–Kwong on the basis of modified Huron–Vidal mixing rule (SRK/MHV2) applied to evaluate vapor–liquid equilibrium behavior. The highest precision in predicting the experimental data by the suggested kinetic model was assigned to methanol conversion. The outcomes presented the high temperature is suitable for higher CO yield, methanol and CO2 conversions. An augmentation in carbon dioxide percentage of the inlet feed led to enhance in CO yield, methanol and CO2 conversions, while H2 yield was decreased.

Phase Behavior and Physical Properties of Dimethyl Ether/Water/Heavy-Oil Systems Under Reservoir Conditions

SummaryPhase behavior and physical properties including saturation pressures, swelling factors (SFs), phase volumes, dimethyl ether (DME) partition coefficients, and DME solubility for heavy-oil mixtures containing polar substances have been experimentally and theoretically determined. Experimentally, novel phase behavior experiments of DME/water/heavy-oil mixtures spanning a wide range of pressures and temperatures have been conducted. More specifically, a total of five pressure/volume/temperature (PVT) experiments consisting of two tests of DME/heavy-oil mixtures and three tests of DME/water/heavy-oil mixtures have been performed to measure saturation pressures, phase volumes, and SFs. Theoretically, the modified Peng-Robinson equation of state (EOS) (PR EOS) together with the Huron-Vidal mixing rule, as well as the Péneloux et al. (1982) volume-translation strategy, is adopted to perform phase-equilibrium calculations. The binary-interaction parameter (BIP) between the DME/heavy-oil pair, which is obtained by matching the measured saturation pressures of DME/heavy-oil mixtures, works well for DME/heavy-oil mixtures in the presence and absence of water. The new model developed in this work is capable of accurately reproducing the experimentally measured multiphase boundaries, phase volumes, and SFs for the aforementioned mixtures with the root-mean-squared relative error (RMSRE) of 3.92, 9.40, and 0.92%, respectively, while it can also be used to determine DME partition coefficients and DME solubility for DME/water/heavy-oil systems.

Thermodynamic Evaluation of the Intermediate Liquid Compounds (ILC) from Biomass Fast Pyrolysis

Biomass fast pyrolysis process is a technology that converts renewable solids into a dense liquid. This study aims to apprehend the thermodynamic behaviour of the Intermediate Liquid Compounds (ILCs) observed during the biomass fast pyrolysis. The system studied was a closed system (20 mL) with air and a mixture solution of five components (Acetic acid (AA), hydroxyacetone (HX), phenol; furfural (FF) and methanol) at 90°C and under atmospheric pressure. The flash calculation was conducted at a given temperature and pressure. The vapor-liquid equilibrium compositions were determined combining equation of state and activity coefficient models, the Soave-Redlich-Kwong (SRK) equation of state coupled with Modified Huron-Vidal (MHV2) mixing rules incorporating the UNIversal Functionnal Activity Coefficient (UNIFAC) model. Theoretical calculations of vapor-liquid equilibrium compositions were experimentally validated by using a Head-Space GC-MS system. A quantitative agreement between simulated and measured concentrations in the liquid phase was achieved with this combined state-predictive model of SRK-MHV2-UNIFAC model; thus, confirming that it accounts well for the nonidealities.

A comparative performance evaluation of cubic equations of state for predicting the compositional distribution of hydrate inhibitors in reservoir fluid systems

This study presents a comparative computational examination of different cubic equations of state (EoS) on hydrate inhibition fluid systems involving real reservoir fluids. Two gas hydrate inhibitors (Monoethylene glycol – MEG and methanol) were considered alongside 4 cubic EoS namely; Cubic-Plus-Association (CPA) EoS coupled with Infochem mixing rules, Soave-Redlich-Kwong (SRK) EoS coupled with the Huron-Vidal (HV) mixing rule, Peng Robinson EoS coupled with the HV mixing rule and the Predictive-Soave-Redlich-Kwong EoS with the PSRK-type mixing rule. Pressure-Temperature (PT) – flash calculations were carried out using MultiflashTM software (version 6.1) and the obtained results were compared with experimental data from various literature. The tested Cubic EoS successfully modelled the distribution of water, a hydrate inhibitor and hydrocarbons in the complex mixtures at different conditions with the CPA EoS performing best. The PSRK EoS produced results farthest from experimental data.

Toward accurate density and interfacial tension modeling for carbon dioxide/water mixtures

Phase behavior of carbon dioxide/water binary mixtures plays an important role in various CO2-based industry processes. This work aims to screen a thermodynamic model out of a number of promising candidate models to capture the vapor–liquid equilibria, liquid–liquid equilibria, and phase densities of CO2/H2O mixtures. A comprehensive analysis reveals that Peng–Robinson equation of state (PR EOS) (Peng and Robinson 1976), Twu α function (Twu et al. 1991), Huron–Vidal mixing rule (Huron and Vidal 1979), and Abudour et al. (2013) volume translation model (Abudour et al. 2013) is the best model among the ones examined; it yields average absolute percentage errors of 5.49% and 2.90% in reproducing the experimental phase composition data and density data collected in the literature. After achieving the reliable modeling of phase compositions and densities, a new IFT correlation based on the aforementioned PR EOS model is proposed through a nonlinear regression of the measured IFT data collected from the literature over 278.15–477.59 K and 1.00–1200.96 bar. Although the newly proposed IFT correlation only slightly improves the prediction accuracy yielded by the refitted Chen and Yang (2019)’s correlation (Chen and Yang 2019), the proposed correlation avoids the inconsistent predictions present in Chen and Yang (2019)’s correlation and yields smooth IFT predictions.

Modeling Vapor–Liquid Equilibria and Surface Tension of Carboxylic Acids + Water Mixtures Using Peng–Robinson Equation of State and Gradient Theory

This work has been dedicated to modeling the vapor–liquid equilibria and surface tension of carboxylic acids + water mixtures at different temperatures. The Peng–Robinson equation of state with modified Huron–Vidal + Wilson mixing rule correctly models the vapor pressure and vapor mole fraction of these mixtures. The modified Huron–Vidal mixing rule was better than quadratic mixing rule to model the phase equilibria properties for the mixtures studied in this work. The parachor method and linear gradient theory were used to model the surface tension of these mixtures. Finally, a new symmetric parameter dependent on the liquid molar fraction and temperature was necessary to correctly adjust the surface tension of the carboxylic acids + water mixtures using linear gradient theory. The surface tension results obtained in this work are better than those published so far.

On the water content in CO2 + CH4 and CO2-rich mixtures: Experimental and modelling evaluation at temperatures from 233.15 to 288.15 K and pressures up to 15 MPa

An experimental and modelling investigation of water content in CO2+CH4 and CO2-rich mixtures in equilibrium with hydrates or liquid water was carried out at temperatures between 233.15 and 288.15 K at pressures up to 15 MPa. Some measurements were undertaken in two-phase region, in the presence of hydrates, with liquid and vapour compositions also reported. Predictions from cubic-plus association SRK, SRK incorporating NRTL with Huron-Vidal mixing rules and multiparametric EoS-CG/GERG equations of state were compared with experimental data. In comparison with pure carbon dioxide, the addition of small amounts of impurities (permanent gases and/or hydrocarbons) resulted in a significant reduction in the water content of the fluid phases present. Overall, sCPA showed good agreement with experimental data, although SRK-HV-NRTL gave better results for some cases, despite the use of only two adjustable parameters. By contrast, multiparametric EoS-CG yielded poor representation of the experimental data. In the two-phase region, no matter the equation of state used, a tendency to underestimate water content in the liquid phase was observed.

Isobaric vapor – liquid – liquid equilibrium for water + MTBE + alcohol (ethanol or 1-butanol) mixtures

Vapor – liquid – liquid equilibrium (VLLE) for water + MTBE + ethanol and water + MTBE + 1-butanol ternary systems have been measured in a modified dynamic Guillespie type cell at the isobaric condition of 101.3 kPa and over the temperature range from 325.6 to 328.9 K for water + MTBE + ethanol mixture and from 329.5 to 355.1 K for water + MTBE + 1-butanol mixture. The quality of the measured data is thermodynamically validated by the L/W Wisniak's consistency point- point test. According to the experimental results, the liquid – liquid equilibria are Type I for water + MTBE + ethanol mixture and Type II for water + MTBE + 1-butanol mixture. The VLLE for water + MTBE + ethanol mixture displays heterogeneous ternary azeotrope whereas the water + MTBE + 1-butanol mixture is a zeotropic ternary mixture. The experimental VLLE data for both ternary mixtures are correlated by a modified version of the nonrandom two-liquids (NRTL) activity coefficients model, which incorporates a ternary contribution. This ternary contribution reduces the global average absolute deviation from 5 % to 1.3 % for water + MTBE + ethanol mixture and from 3.1% to 1.9 % for water + MTBE + 1-butanol mixture.The experimental isobaric VLLE data of the ternary mixtures are also accurately modeled by applying the Peng–Robinson Stryjek–Vera equation of state appropriately extended to mixtures employing the modified Huron–Vidal mixing rule with the NRTL activity coefficient model. This model allows directly transferring the experimental excess Gibbs energy function to the EoS model for equilibrium calculation purposes. This theoretical framework shows that experimental VLLE data can be accurately predicted and provide a route to interpolate values of the phase equilibrium.

Vapor–liquid equilibrium at 94 kPa and surface tension at 298.15 K for hexane + ethanol + cyclopentyl methyl ether mixture

Vapor-liquid equilibrium (VLE) and surface tension (ST) for the hexane + ethanol + cyclopentyl methyl ether mixture have been measured and modeled. VLE determinations are carried out in a dynamic Guillespie type cell at the isobaric condition of 94 kPa, whereas the dependence of ST on concentration is measured in a maximum differential bubble pressure tensiometer at atmospheric pressure and 298.15 K.The thermodynamical consistent VLE data exhibit positive deviation from ideal behavior without ternary azeotropy and are well correlated by Redlich–Kister expansion and predicted by the binary nonrandom two-liquid, Wilson and universal quasichemical activity coefficient models. The ST data exhibit negative deviation from the linear behavior and are smoothed using the Myers-Scott expansion, showing no ternary aneotropic behavior.The experimental data of VLE and ST are accurately characterized by applying the square gradient theory to the Peng–Robinson Stryjek–Vera equation of state (EoS) appropriately extended to mixtures employing the modified Huron–Vidal mixing rule. This theoretical framework shows that experimental VLE and ST data can be fully predicted by only using binary contributions within a global average absolute deviation of 1.25% for VLE and 6.1% for ST. The theoretical approach also provides a route to explore the concentration distribution of species in the interfacial region, where it is possible to conclude that hexane exhibits both adsorption and desorption; ethanol displays strong positive adsorption whereas CPME does not exhibit surface activity.

Towards accurate phase behavior modeling for hydrogen sulfide/water mixtures

Many deep gas wells contain acid gas components. Hydrogen sulfide (H2S) is one of the typical acid gases. Accurate flow simulations for H2S/H2O mixtures in reservoirs and wellbores requires a proper thermodynamic model that is capable of accurately modeling the H2S/H2O mixtures under in-situ conditions. This study aims at screening and developing cubic-equation-of-state-based thermodynamic models that can well describe the phase behavior of H2S/H2O mixtures. Peng-Robinson equation of state (PR EOS) (Peng and Robinson, 1976) and the Huron-Vidal (HV) (Huron and Vidal, 1979) mixing rule are used as the primary modeling framework. The temperature-dependent binary interaction parameter (BIP) correlations in the HV mixing rule are established by matching the measured vapor-liquid equilibria (VLE) data for H2S/H2O mixtures collected from the literature. The experimental VLE data cover a temperature range of 273.15–627.85 K and a pressure range of 0.41–303 bar, while the experimental density data cover a temperature range of 294.35–705.30 K and pressures up to 350 bar. Different volume translation strategies are examined in terms of their accuracy in reproducing the measured density data for H2S/H2O mixtures. We employ PR EOS together with the optimal BIP strategy in the HV mixing rule to reproduce the mutual solubility of H2S and H2O in VLE. The calculated results show a good agreement with the experimental data, especially at high temperatures and pressures; the average absolute percentage deviation (%AAD) of 4.90% and 4.95% can be obtained for reproducing the vapor-phase H2O solubility and the aqueous-phase H2S solubility, respectively. With the inclusion of the volume translation model proposed by Abudour et al. (2013), PR EOS together with the optimal BIP strategy in the HV mixing rule shows a good performance in estimating the aqueous-phase density for H2S/H2O VLE, i.e., an %AAD of 5.42% in reproducing the measured density data.

Isobaric vapor–liquid equilibrium and isothermal surface tension for hexane + cyclopentyl methyl ether binary mixture: Experimental determinations and theoretical predictions

This work reports the measurements and the theoretical predictions of the vapor–liquid equilibrium (VLE) at the isobaric conditions of 50, 75, and 94 kPa and over the temperature range from 332 K to 372 K and the surface tensions (ST) at atmospheric pressure (101.3 kPa) and the isothermal condition of 298.15 K in the whole mole fraction range for the hexane + cyclopentyl methyl ether binary mixture. The experimental determinations of VLE are carried out in a dynamic all-glass Guillespie type cell, where both vapor and liquid phases are circulating. The ST measurements are obtained from a maximum differential bubble pressure tensiometer. The theoretical predictions of VLE and ST are carried out by applying the square gradient theory to the Peng–Robinson Stryjek-Vera equation of state, appropriately extended to mixtures with a modified Huron–Vidal mixing rule, where the excess Gibbs energy is obtained from classical models whose parameters are obtained from the VLE data reported here.Experimental results of VLE show that this mixture is zeotropic and exhibits a slight positive deviation from ideal behavior over the experimental range. ST, in turn, exhibits negative deviation from the linear behavior. The measured VLE data of this binary mixture satisfy the Fredenlund's consistency test and are well-correlated by classical activity coefficients models (e.g., the Wohl, nonrandom two-liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC)) for all of the isobaric conditions. According to the results, the NRTL activity coefficients model is the most appropriate model to describe the VLE of this semi-ideal binary mixture. The dependence of surface tensions on mole fraction is satisfactorily smoothed using the Myers-Scott equation.The theoretical approach uses the pure fluids properties and the NRTL activity coefficients model to predict both VLE and ST. According to the results, this full predictive schema is able to reproduce VLE and ST with an absolute average deviation of 1.0% and 1.2%, respectively. Additionally, the square gradient theory describes a surface activity of hexane, which increases with the bulk mole fraction of hexane until it reaches a maximum value at 0.63 mol fraction of hexane. This interfacial behavior enhances the concentration of hexane at the interfacial region over the corresponding bulk phases concentration.