Interfacial Tension Data Research Articles

Calculation of interfacial tension of binary systems containing water and an organic component by group contribution methods

This work proposes a predictive method for estimating liquid-liquid interfacial tension (IFT) by group contribution methods of systems containing water and an organic component. The model for calculating the interfacial tension of liquid–liquid systems was derived using a general thermodynamic framework that was empirically extended by the introduction of an effective interfacial area. The effective interfacial area is defined for each component and takes into account the effects of groups of the other component present at the liquid-liquid interface. In addition, the interfacial molar volume was estimated by a mixing rule, using the molar volume of pure components in the liquid phase, weighted by the equilibrium compositions calculated by the UNIFAC model. The corresponding thermophysical properties were obtained by a group contribution method, in which a temperature-dependent binary parameter was proposed. This parameter is given by the sum of contributions related to each group present in the molecule, with values estimated from an experimental database of interfacial tension of water and different organic compounds. Therefore, the model can be used to predict the interfacial tension of binary mixtures in different temperatures through the knowledge of the structure of the organic component. The values of the model parameters were determined by a parameter estimation procedure based on an extensive database, covering 546 interfacial tension data of liquid-liquid binary systems containing water and an organic component. The model predicts interfacial tension data for binary systems containing organic compounds with different chemical functions in equilibrium with water, including oxygenated organic compounds, which are rarely predicted with good accuracy. The total mean absolute deviation obtained from this method was 1.20 mN⋅m−1, better than other predictive model and also better than some correlative models available in the literature.

Review on chemical enhanced oil recovery: Utilization of ionic liquids and deep eutectic solvents

The increasing demand for oil production requires the extraction of oil obtained from not only primary and secondary stages, but also tertiary recovery methods in order to meet increasing global demand on the power requirement. Therefore, enhanced oil recovery (EOR) is expected to increase their relevance in the coming years. Physical gas injection and thermal methods have been used for EOR for a while; however, due to its limited applicability and high operating cost, chemical-based EOR processes have been considered a promising alternative considering higher efficiency, technical and economic feasibilities, and reasonable capital cost requirements. Therefore, the search and design of new chemical compounds are of pivotal relevance for the oil and gas industry to boost reservoir production. Among the new types of compounds considered for chemical EOR, ionic liquids (IL) and deep eutectic solvents (DES) have gained considerable attention over the last few years. The purpose of this review is to review the database of published work on these compounds and analyze ILs and DESs performance in the EOR process. The possible mechanisms of action of both types of fluids, their suitability, and problems, as well as economic factors, are studied. The details of experimental results on rock wettability, core flooding performance and interfacial tension data for both ILs and DESs have been examined. The pros and cons of these fluids compared to the available traditional chemical enhanced oil recovery methods have been discussed, and the marginal effect on EOR performance via ILs and DESs has been highlighted. Guidelines for designing and developing new ILs and DES for EOR have been provided to obtain more sustainable and environmentally friendly chemicals suitable for EOR operations.

Modelling of continuous surfactant flooding application for marginal oilfields: a case study of Bentiu reservoir

Enhanced oil recovery (EOR) is a proven method to increase oil production from the brown fields. One of the efficient EOR methods is injecting surfactants to release the trapped oil. However, few unconsolidated behaviours were observed in both field and laboratory practice. In this study, a new framework was adapted to evaluate the continuous surfactant flooding (CSF) in Bentiu reservoir. The study aims to quantify the expected range of the oil production, recovery factor and residual oil saturation (Sor). The motivation came from the oil demand in Sudan and the insufficient cores. The framework adopted in the study includes numerical simulation modelling and proxy modelling. Thirty-six cores obtained from the field were revised and grouped into five main groups. The interfacial tension (IFT) data were obtained experimentally. The CSF sensitivity study was developed by combining different experimental design sets to generate the proxy model. The CSF numerical simulation results showed around 30% additional oil recovery compared to waterflooding and approximately oil production between (20–30) cm3. The generated proxy model extrapolated the results with concerning lower ranges of the input and showed an average P50 of oil production and recovery of 74% and 17 cm3, respectively. Overall, the performance of CSF remained beneficial in vast range of input. Moreover, the generated proxy model gave an insight on the complexity of the interrelationship between the input factors and the observants with a qualitative prospective factors. Yet, the results confirmed the applicability of CSF in core scale with an insight for field scale application.

Prediction of live reservoir fluid interfacial tension from dead oil measurements

The interfacial tension (IFT) between crude oil and water governs the multiphase flow in porous media and is therefore of paramount importance for understanding reservoir behavior. IFT data is commonly, but inadequately, acquired at ambient conditions using samples of dead oil, because live crude oil samples are limited in availability and measurements under high pressure and temperature conditions are complex. In this study, ten live crude oil samples were used to establish the first correlation allowing to predict live crude oil interfacial tension based on dead oil IFT values and conventional PVT data. IFT experiments were executed for all samples at different pressure and temperature conditions. A common trend of IFT increase from the dead oil at ambient to the live oil at reservoir conditions was noted in the experiments. Based on the measured data, a correlation was established to predict live oil IFT at reservoir conditions from dead oil IFT at ambient condition, using dead oil viscosity and molecular weight, as well as gas to oil ratio and fluid densities as input parameters. The correlation showed a strong coefficient of determination (R2 = 0.98) and was validated using three additional live crude oils from different fields. The IFT values at reservoir conditions were well predicted with average errors below 5%.

The effect of brine salinity and oil components on dynamic IFT behavior of oil-brine during low salinity water flooding: Diffusion coefficient, EDL establishment time, and IFT reduction rate

Dynamic behavior of fluid-fluid interactions can potentially affect the performance of any enhanced oil recovery (EOR) process including low salinity water flooding. In this work, dynamic interfacial tension (IFT) of crude-oil/brine system is measured in a wide range of salinity of sea water (SW), from 50-time diluted sea water (SW50D) to 2-time concentrated sea water (SW2C). Contrary to the most of published IFT trends in the literature, for the system under investigation here, as the brine salinity increases the crude-oil/brine IFT reduces, which cannot be explained using the existing theories. The lack of a physical model to explain the observed phenomena was the motivation to develop a new model based on a drift-diffusion theory. This theory considers a current of oil polar molecules toward the oil-water interface which is caused by electrostatic attraction from aqueous ions (drift) and a resistance against this current caused by concentration gradient (diffusion). After applying this model to measured dynamic IFT data, the IFT reduction rate, and electrical double layer (EDL) establishment time are calculated. Then, these matching parameters set as criteria to explain the mechanisms behind the dynamic behavior of crude oil-saline water interfacial tension.For further investigation of the involved mechanisms which are responsible for the macroscopic behavior of crude-oil/brine dynamic IFT, the role of oil components is also examined using the IFT reduction rate and EDL establishment time. Although the obtained results show the asphaltene molecules play a vital role in the dynamic IFT behavior, the concentration of n-heptane, in the model oil containing n-heptane and toluene, is essential to capture the IFT behavior of the crude oil. Increasing n-heptane fraction in the model oil to the amount which exist in the crude oil, results in longer EDL establishment time which is in agreement with the crude oil sample.

Entropy of resilience: Formulism and validation using strained-induced surface wettability study on thin film alloys

To circumvent the lack of interfacial tension data, we introduced a new material thermodynamics property termed as entropy of resilience SR to promote the application of Young’s equation. Derived from Helmholtz free energy analysis, this property relates to a specimen’s reduction in entropy and heat formation process. Moreover, we demonstrate a non-linear entropy-strain relationship, and proposed entropy change can be characterized by tensile tests and water contact angle measurements. Hence, water contact angle change is established as a second-degree polynomial function of strain, validated by surface wetting measurement of intrinsically strained thin film NiTi. Accordingly, a ∼60° increase in water contact angle can be interpreted as an entropy reduction of 38.61 Jkg−1K−1. This newly defined concept of entropy of resilience corresponds to a new paradigm shift wherein entropy is regarded as the predominate thermodynamic driver of surface wetting.

On the study of the vapor-liquid interface of associating fluids with classical density functional theory

Classical density functional theory (DFT) is applied to study the vapor-liquid interface of associating fluids. Our classical DFT implementation uses a Helmholtz free energy functional that reduces to the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state in the bulk limit. We apply a new association functional, presented in one of our previous works, based on the weighted density approximation to calculate the interfacial tension of associating fluids and compare them with two of the most used association functionals from literature. It is found that classical DFT with the three association functionals and the current molecular parameters of PC-SAFT is not able to predict satisfactorily the interfacial tension of alkanols. Therefore, the experimental interfacial tension of alkanols and some associating fluids is included in the determination of the pure molecular parameters of PC-SAFT. With this approach the determination of interfacial tension of pure associating fluids can be greatly improved with the new parameters, but at the expense of slightly higher deviations in the vapor pressure. The new parameters are tested for the determination of vapor-liquid equilibria (VLE) and the prediction of interfacial tension of binary mixtures containing at least one associating compound. Good agreement is found between experimental data of VLE and interfacial tension of the binary mixtures and the three association functionals. Furthermore, we discuss about the limitations and capabilities of the current classical DFT implementation in the study of the vapor-liquid interface of associating fluids.

The superior effects of a long chain gemini ionic liquid on the interfacial tension, emulsification and oil displacement of crude oil-water

Gemini ionic liquid (IL) type surfactants, with high interfacial activity and environment friendly nature have revealed desired potentials for enhanced oil recovery (EOR). In this study, a long chain gemini imidazolium IL, namely [C12im-C4-imC12]Br2, was synthesized and its effect on different properties of the crude oil-water system was investigated. Significant changes in the system interfacial tension (IFT), micellization, emulsification and wettability were observed. A drastic reduction in IFT under the IL bulk concentrations of less than 0.2 mol dm−3 and achieving the ultra-low IFTs to about 8.2 × 10−3 mN m−1 (99.97% reduction) were appropriate. Increasing temperature (within 298.2–323.2 K) favored the function of the IL. Moreover, achieving stable emulsion of more than 52% after one week and oil displacement phenomenon at elevated IL concentrations were observed. Comparison of the results with two homolog shorter alkyl chain ILs, revealed the superior impact of the used IL. The Frumkin adsorption isotherm nicely reproduced the IFT data and the corresponding parameters as well as thermodynamic quantities were obtained.

Experimental and modeling investigations of the interfacial tension of three different diesel + nitrogen mixtures at high pressures and temperatures

Interfacial tension (IFT) data are reported at temperatures up to 530 K and pressures up to 100 MPa for mixtures of N2 with a highly paraffinic diesel, an ultra-low sulfur diesel, and a highly aromatic diesel. The impact of composition on the IFT is determined by comparing data for each system at the same temperature and pressure calculated from a Tait-like relationship fit to the experimental data. The greatest differences in diesel + N2 IFT values are found near the normal boiling point (Tboil) of each diesel where lower molecular weight diesel components begin to dissolve in the N2-rich vapor phase. IFT data are modeled with density gradient theory (DGT) coupled with the perturbed-chain, statistical associating fluid theory equation of state (EoS). Diesel EoS parameters are calculated using three variations of a pseudo-component technique created from one group contribution (GC) method developed from high-pressure density data and from two other GC methods (S-GC and T-GC) developed from differing sets of pure component vapor pressure and saturated liquid density data. The IFT predictions significantly improve when the DGT influence parameter, cii, is allowed to vary with temperature. The DGT predictions with the B-GC method are in closest agreement with data at temperatures below Tboil, which is attributed to the more accurate representation of liquid phase densities. However, at temperatures above Tboil, where significant amounts of low molecular weight diesel components dissolve in the N2-rich vapor phase, DGT predictions with the S-GC and T-GC methods provide the closest agreement with IFT data.

How do ions contribute to brine-hydrophobic hydrocarbon Interfaces? An in silico study

HypothesisThe saltwater-oil interface is of broad implication in geochemistry and petroleum disciplines. To date, the main focus has been on the surface contribution of polar, heavy compounds of crude oil, widely neglecting the role of non-polar hydrocarbons. However, non-polar compounds are expected to contribute to characteristics of oil-brine interfaces. MethodologyUtilizing molecular dynamics simulation, we aim to characterize ion behavior adjacent to hydrophobic organic phases. Concerning natural environments, NaCl, CaCl2 and Na2SO4 electrolytes at low (5 wt%) and high (15 wt%) concentrations were brought in contact with heptane and/or toluene which account for aliphatic and aromatic constituents of typical crude oils, respectively. The reproduced experimental data for interfacial tension, brines density and ions’ diffusivities adequately verify our molecular calculations. FindingsIons accumulate nearby the intrinsically charge-neutral oil surfaces. A disparate surface-favoring propensity of ions causes the interfacial region to resemble an electrical layer and impose an effective surface charge onto the oil surface. Despite absence of any polar site, the effective surface charge density is hydrocarbon-dependent, with the highest and lowest values observed for toluene and heptane interfaces, respectively. Due to accumulation of toluene molecules nearby the brines, the interfacial characteristics of heptol (toluene-heptane mixture) is comparable to that of the toluene phase.

Determination of equivalent alkane carbon number for West Siberian oils as a stage of optimisation in surfactant-polymer compositions for chemical flooding

The hydrophobicity of and products can be characterised in terms of its equivalent alkane carbon number (EACN). This characteristic can be determined on the basis of the correlation between the interfacial tension data and other characteristics for homologous oils and a number of alkanes having subsequent interpretation for and products. The EACN is a useful metric for selecting an effective surfactant for the emulsification of and products. The research is aimed at determining the equivalent alkane car-bon number of various crude samples obtained in the fields of Western Siberia using standard high-performance compositions of imported and domestic industrial sulphonate surfactants. In order to determine the EACN of and products, the S* characteristic was applied representing the optimal NaCl concentration (optimum salinity) in the aqueous surfactant phase, as well as providing the minimum surface tension and formation of the maximum microemulsion volume during the phase experiment at the interface with the hydro-carbon phase. Direct determination of the interfacial tension at the oil / surfactant solution interface was car-ried out with a tensiometer using the spinning drop method at a temperature of 87 ° С . Linear dependencies are identified in accordance to the empirical correlation equations between the EACN, surfactant parameters and phase behaviour parameters of aqueous surfactant solutions and or a mixture of hydrocarbons. The K characteristic parameter of the proposed three standard surfactant compositions is determined to be consistent with the literature data for individual surfactants. The composition of industrial surfactants for determining the EACN of and products is proposed. The equations of linear regression for the logS* ~ EACN dependency with high correlation coefficients (R² = 0.9444-0.9999) are obtained, resulting in the determination of the EACN for kerosene and seven samples from Western Siberian fields. Promising surfactants can be selected on the basis of this indicator for reducing interfacial tension in the hydrocarbon / water solution system, as well as for predicting the most effective composition for obtaining emulsions.

Study of Asphaltene Precipitation during CO2 Injection into Oil Reservoirs in the Presence of Iron Oxide Nanoparticles by Interfacial Tension and Bond Number Measurements

CO2 injection is one of the most frequently used enhanced oil recovery methods; however, it causes asphaltene precipitation in porous media and wellbore and wellhead facilities. Carbon dioxide saturated with nanoparticles can be used to enhance oil recovery with lower asphaltene precipitation issues. In this study, the vanishing interfacial tension technique was used to investigate the possibility of diminishing asphaltene precipitation by nanoparticles. The interfacial tension (IFT) of synthetic oil/carbon dioxide was measured using the pendant drop method. The results illustrated that, for synthetic oil samples containing asphaltene, the IFT data versus pressure decrease linearly with two different slopes at low- and high-pressure ranges. At high pressures, the slope of the plot is lower than the one in the low-pressure range. The addition of iron oxide nanoparticles to the oil solution reduces the interfacial tension at higher pressures with a steeper slope, showing that nanoparticles can decrease asphaltene precipitation. The plot of Bond number versus pressure also confirmed the impact of nanoparticles on reducing asphaltene precipitation. In terms of the temperature effect, the presence of nanoparticles at 50 °C resulted in a 16.34% reduction in asphaltene precipitation and a 19.65% reduction at 70 °C. The minimum miscibility pressure changed from 10.17 to 30.96 MPa at 70 °C; however, in the presence of nanoparticles, it reduced from 10.06 to 16.56. Therefore, the technique introduced in this study could be applied to avoid the problems associated with altering the gas injection mode from miscible to immiscible.

An Analytical Model for Estimation of the Self-Diffusion Coefficient and Adsorption Kinetics of Surfactants Using Dynamic Interfacial Tension Measurements.

We report a new analytical approach to model the transient diffusion and adsorption kinetics of a surfactant at a liquid/liquid interface using dynamic interfacial tension data. The developed model combined with the Frumkin/Langmuir isotherm is used to reproduce the experimental data of dynamic interfacial tension and predict the surfactant diffusion coefficient from a bulk solution to an interface and its adsorption kinetics. Experimental data of the dynamic interfacial tension of toluene and heptol solutions at various concentrations of asphaltenes (a natural surfactant) were employed to examine the ability of the developed model to regenerate the dynamic interfacial tension data. The model enabled us to estimate the apparent diffusion coefficient and adsorption kinetics of asphaltenes at different concentrations. The results showed that the diffusive migration of asphaltene toward an oil/water interface decreases at its higher concentrations and increases at higher concentrations of an aliphatic solvent such as n-heptane. Furthermore, the results reveal that the adsorption rate of asphaltenes at the interface increases at higher concentrations of surfactants and the aliphatic solvent. The developed analytical model finds applications in the prediction of the diffusion and adsorption kinetics of surfactants using dynamic interfacial tension data.

Brine-Oil Interfacial Tension Modeling: Assessment of Machine Learning Techniques Combined with Molecular Dynamics.

The physical chemistry mechanisms behind the oil-brine interface phenomena are not yet fully clarified. The knowledge of the relation between brine composition and concentration for a given oil may lead to the ionic tuning of the injected solution on geochemical and enhanced oil recovery processes. Thus, it is worth examining the parameters influencing the interfacial properties. In this context, we have combined machine learning (ML) techniques with classical molecular dynamics simulations (MD) to predict oil/brine interfacial tensions (IFT) effectively and compared this process to a linear regression (LR) method. To diversify our data set, we have introduced a new atomistic crude oil model (medium) with 36 different types of hydrocarbon molecules. The MD simulations were performed for mono- and multicomponent (toluene, heptane, Heptol, light, and medium) oil systems interfaced with sulfate and chloride brines with varying cations (Na+, K+, Ca2+, and Mg2+) and salinity concentration. Thus, a consistent IFT data set was built for the ML training and LR fitting at room temperature and pressure conditions, over the feature space considering oil density, oil composition, salinity, and ionic concentrations. On the basis of gradient boosted (GB) algorithms, we have observed that the dominant quantities affecting the IFT are related to the oil attributes and the salinity concentration, and no specific ion dominates the IFT changes. When the obtained LR model was validated against MD and experimental data from the literature, the error varied up to 2% and 9%, respectively, showing a robust and consistent transferability. The combination of MD simulations and ML techniques may provide a fast and cost-effective IFT determination over multiple and complex fluid-fluid and fluid-solid interfaces.

Synthesis and application of castor oil maleate and castor oil maleate-styrene copolymers as demulsifier for water-in-oil emulsions

Oil industry has encountered a series of difficulties associated with flow assurance of petroleum fluids, especially those related with stable emulsion formation. Such emulsified systems could present problems during transportation, handling, and refining, because of their relation to operational factors, as follows: fluid viscosity, processing energy expenditure, and water coproduction. For this reason, the addition of interfacial active compounds, often polymers, is used in an attempt to phase separation in industrial processes. In this paper, five different chemical surfactants, referred to here as MACO 1, MACO 2, R1, R2, and R3, were synthesized based on castor oil. These additives were characterized by Fourier Transform Infrared (FTIR), Size-Exclusion Chromatography (SEC), and Thermogravimetrical Analyses (TGA). The demulsification activity was studied in synthetic emulsions by using two Brazilian crude oils and 30% (v/v) brine cut with 60 and 240 g/L NaCl, at neutral pH, and average droplet diameter of 10 μm. Bottle tests were carried out at 60 °C in graduated ASTM test tubes for 2 h, varying additive concentration from 100 to 5000 ppm. Interfacial tension measurements were performed to elucidate the demulsification activity in water-oil interface, at the same bottle test experimental conditions. These results were discussed on the basis of the oil characterization, mechanisms of demulsifying action, as well as interfacial tension data. Ward and Tordai equation was applied according to asymptotic approximations to evaluate additives diffusivity. The results show that demulsification is more significant for MACO 1, with maximum water resolution of around 90% for both emulsion systems.

Interfacial Tension ofn-Pentane/Bitumen andn-Heptane/Bitumen Mixtures atT= 298.15–413.15 K andP= 3.45 MPa

We report new interfacial tension (IFT) data of n-pentane/bitumen and n-heptane/bitumen mixtures at T = 298.15–413.15 K, P = 3.45 MPa, and four concentrations of the n-pentane and n-heptane (10, 20...

Is interfacial tension of a liquid-air interface thermodynamically a cyclic process?

Brønsted (log kB = β pKaHB + C) and Taft (log k = ρ*σ* + log ko) linear free energy equations are applied to the interfacial tension data of N-substituted anilines. The significance of the values of the constants Brønsted β (0.096) and Taft ρ* (0.091) are explained in terms of proton transfer from the acid to the aniline, which is accelerated by electron donating groups. The deprotonation of protonated aniline is accelerated by electron withdrawing groups. Since any thermodynamic property associated with any kind of reaction is a point group, the fact that Brønsted β and Taft ρ* have similar values with opposite sign indicates that the total process taking place at the aniline-air interface is a cyclic one.

Investigation on the adsorption mechanism and model of didodecyldimethylammonium bromide on ZnO nanoparticles at the oil/water interface

We systemically evaluated the effects of the additional ZnO nanoparticles (NPs) on the interfacial activity of the cationic surfactant didodecyldimethylammonium bromide (DDAB) with two hydrophobic chains by the interfacial tension (IFT) measurement and emulsification experiments. The addition of ZnO NPs greatly improved the interfacial activity of the mixed ZnO/DDAB system at the oil/water interface. The zeta potential and fluorescence spectra of the mixed ZnO/DDAB dispersions were investigated to explore the adsorption behavior of DDAB molecules on ZnO NP surfaces. The IFT between a homologous series of n-alkanes and DDAB aqueous solutions in the absence and presence of ZnO NPs was measured to explore the mechanism of the further IFT reduction caused by the additional ZnO NPs. The dynamic IFT data were fitted with two different models. The results indicated that the DDAB adsorption processes in the absence and presence of ZnO NPs were controlled by the mixed diffusion-kinetic controlled model.

Wetting behavior and interfacial tension of a refrigerant oil in air and refrigerant atmospheres

In the present study, the wettability of ground AISI 321 steel and PTFE surfaces with a polyalkylene glycol-based lubricant in air and 1,1,1,2-tetrafluoroethane (R-134a) atmospheres is characterized. For this, spreading velocities are determined from videos recorded during the continuous dosing of lubricant on the solid surfaces. The results are compared with interfacial tension data for the lubricant measured by the pendant-drop method in air and R-134a atmospheres. Significantly higher wettability was found in the presence of refrigerant atmosphere, on the steel surface and along its grinding grooves, whereas no consistent temperature-dependent trends could be identified. The interfacial tension of the lubricant decreases with increasing temperature at ambient air atmosphere as well as with increasing R-134a pressure at a fixed temperature. The temperature-dependent behavior of the interfacial tension for a given refrigerant pressure is affected by the temperature itself and by the resulting solubility of the refrigerant in the lubricant.

Interfacial Tension and Liquid Viscosity of Binary Mixtures of n-Hexane, n-Decane, or 1-Hexanol with Carbon Dioxide by Molecular Dynamics Simulations and Surface Light Scattering

In the present study, the interfacial tension and liquid viscosity of binary mixtures of n-hexane, n-decane, or 1-hexanol with carbon dioxide (CO2) were investigated by molecular dynamics (MD) simulations and surface light scattering (SLS). The latter technique was applied to study experimentally the influence of dissolved CO2 on the interfacial tension and liquid viscosity of binary mixtures of n-hexane with CO2 at 303.15 K and saturation pressures up to 5 MPa corresponding to a CO2 mole fraction in the liquid phase up to 0.75. For this system at vapor–liquid equilibrium, the liquid viscosity and interfacial tension were determined with average relative expanded uncertainties (k = 2) of (1.8 and 1.3) %. In equilibrium MD simulations for binary mixtures of n-hexane, n-decane, or 1-hexanol with CO2, the vapor–liquid equilibria including saturated densities as well as the interfacial tensions were predicted at temperatures of (303.15, 333.15, and 363.15) K for CO2 mole fractions in the liquid phase up to 0.52. For the binary mixtures of n-hexane with CO2, agreement between the measured and simulated data for viscosity and interfacial tension was found. With the three mixtures investigated by MD simulations, the influence of chain length and hydroxylation on the interfacial tension could be demonstrated. The simulations showed that the magnitude of CO2 enrichment at the vapor–liquid interface is more pronounced for solvents with larger surface tensions.