Surface tension from molecular dynamics simulation: Adsorption at the gas‐liquid interface

Mucha, Martin; Hrobárik, Tomáš; Jungwirth, Pavel

doi:10.1560/ww15-pbew-m3w4-uagn

Cited by 7 publications

(6 citation statements)

References 8 publications

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“…In addition to the phase and component densities, we have also analyzed the surface excess of CO 2 and propane in the studied mixtures. The surface excess relates the IFT to the solute chemical potential via the fundamental thermodynamic expression (eq ) and can be readily calculated from the MD simulation data , using eq . The results are shown in Figure and listed in SI, Tables S2–S4.…”

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO₂/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

2021

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Molecular dynamics (MD) simulations were used to study vapor− liquid equilibrium interfacial properties of n-alkane and n-alkane/CO 2 mixtures over a wide range of pressure and temperature conditions. The simulation methodology, based on CHARMM molecular mechanics force field with long-range Lennard-Jones potentials, was first validated against experimental interfacial tension (IFT) data for two pure n-alkanes (n-pentane and n-heptane). Subsequently, liquid−vapor equilibria of CO 2 /n-pentane, propane/n-pentane, and propane/n-hexane mixtures were investigated at temperatures from 296 to 403 K and pressures from 0.2 to 6 MPa. The IFT, liquid and vapor phase densities, and molecular compositions of the liquid and vapor phases and of the interface were analyzed. The calculated mixture IFTs were in excellent agreement with experiments. Likewise, calculated phase densities closely matched values obtained from the equation of state (EOS) fitted to the experimental data. Examination of the density profiles, particularly in the liquid−vapor transition regions, provided a molecular-level rationalization for the observed trends in the IFT as a function of both molecular composition and temperature. Finally, two variants of the empirical parachor model commonly used for predicting the IFT, the Weinaug−Katz and Hugill−Van Welsenes equations, were tested for their accuracy in reproducing the MD simulation results. The IFT prediction accuracies of both equations were nearly identical, implying that the simpler Weinaug−Katz model is sufficient to describe the IFT of the studied systems.

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Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO₂/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

2021

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“…Studies reporting vapour-liquid interfacial properties focus on a large variety of different systems and applications, such as enhanced oil recovery [18,20,23,[95][96][97][98][99][100], natural gas [19,22,[101][102][103][104][105], CO 2 absorption and carbon-capture and storage (CCS) [20,79,102,[106][107][108][109][110][111], refrigerants [112][113][114][115], evaporation and nucleation [32,116], environmental science [117][118][119], process and chemical engineering [15,17,26,83,108,[120][121][122][123], polymers [124,125], fundamental physics [7,13,14,…”

Section: Review Of Literature Data On the Enrichment At Vapour-liquid Interfaces And Databasementioning

confidence: 99%

“…Long-range interactions were found to have a minor influence on the enrichment in simple fluid mixtures [142]. Also the pressure tensor across vapour-liquid interfaces of mixtures was measured by many authors [9,12,109,119,138,145,164]. The pressure profiles do not exhibit additional oscillations in cases of high E 2 compared to cases with low E 2 .…”

Section: Review Of Literature Data On the Enrichment At Vapour-liquid Interfaces And Databasementioning

confidence: 99%

Enrichment at vapour–liquid interfaces of mixtures: establishing a link between nanoscopic and macroscopic properties

Stephan

Hasse

2020

International Reviews in Physical Chemistry

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Component density profiles at vapour-liquid interfaces of mixtures can exhibit a non-monotonic behaviour with a maximum that can be many times larger than the densities in the bulk phases. This is called enrichment and is usually only observed for low-boiling components. The enrichment is a nanoscopic property which can presently not be measured experimentally -in contrast to the classical Gibbs adsorption. The available information on the enrichment stems from molecular simulations, density gradient theory, or density functional theory. The enrichment is highly interesting as it is suspected to influence the mass transfer across interfaces. In the present work, we review the literature data and the existing knowledge on this phenomenon and propose an empirical model to establish a link between the nanoscopic enrichment and macroscopic properties -namely vapour-liquid equilibrium data. The model parameters were determined from a fit to a dataset on the enrichment in about 100 binary Lennard-Jones model mixtures that exhibit different types of phase behaviour, which has recently become available. The model is then tested on the entire set of enrichment data that is available in the literature, which includes also mixtures containing nonspherical, polar, and H-bonding components. The model predicts the enrichment data from the literature (2,000 data points) with an AAD of about 16%, which is below the uncertainty of the enrichment data. This establishes a direct link between measurable macroscopic properties and the nanoscopic enrichment and enables predictions of the enrichment at vapour-liquid interfaces from macroscopic data alone.

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“…Butt et al, 2006). Surface excess, a rapidly equilibrating property related directly to intermolecular forces, can be readily determined by MD simulation (Mucha et al, 2003). Comparison between simulated and measured CO 2 adsorption by a water surface thus may shed light on the quality of force field parameters.…”

Section: Interfacial Tension and Surface Excessmentioning

confidence: 99%

Predicting CO2–water interfacial tension under pressure and temperature conditions of geologic CO2 storage

Nielsen

Bourg

Sposito

2012

Geochimica et Cosmochimica Acta

143

177

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Storage in subsurface geologic formations, principally saline aquifers, is currently under development as a major approach to counter anthropogenic CO 2 emissions. To ensure the stability and long-term viability of geologic carbon storage, injected CO 2 must be kept in place by an overlying cap rock of very low permeability. Capillary forces in the cap rock act to prevent upward migration and escape of the stored supercritical fluid, with interfacial tension (IFT) between the aqueous brine phase and the CO 2 phase being the primary control. However, published experimental CO 2 -water IFT data vary widely, mainly because of inadequate experimental protocols or inappropriate use of bulk-fluid properties in computing IFT from experimental observations. Only two published data sets were found to meet all criteria of merit for an accurate measurement of IFT over the entire range of pressure (5-45 MPa) and temperature (298-383 K) pertinent to geologic carbon storage. In such circumstances, molecular simulations can enhance the utility of limited data when used to validate assumptions made in their interpretation, resolve discrepancies among data, and fill gaps where data are lacking. Simulations may also be used to provide insight into the relationship between IFT and fundamental properties, such as the strength of the CO 2 -H 2 O interaction. Through molecular dynamics simulations, we compared the quality of three CO 2 models and two H 2 O models (SPC/E and TIP4P2005) in predicting IFT under the pressure and temperature conditions relevant to geologic CO 2 sequestration. Interfacial tension at fixed temperature simulated via molecular dynamics decreased strongly with increasing pressure below the critical CO 2 pressure of 7 MPa, then leveled off, in agreement with experiment, whereas increasing temperature from 300 to 383 K at fixed pressure had little effect on IFT, which is also

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Surface tension from molecular dynamics simulation: Adsorption at the gas‐liquid interface

Cited by 7 publications

References 8 publications

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO₂/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO₂/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

Enrichment at vapour–liquid interfaces of mixtures: establishing a link between nanoscopic and macroscopic properties

Predicting CO2–water interfacial tension under pressure and temperature conditions of geologic CO2 storage

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Surface tension from molecular dynamics simulation: Adsorption at the gas‐liquid interface

Cited by 7 publications

References 8 publications

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO2/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO2/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

Enrichment at vapour–liquid interfaces of mixtures: establishing a link between nanoscopic and macroscopic properties

Predicting CO2–water interfacial tension under pressure and temperature conditions of geologic CO2 storage

Contact Info

Product

Resources

About

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO₂/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures

Molecular Dynamics Simulations of the Vapor–Liquid Equilibria in CO₂/n-Pentane, Propane/n-Pentane, and Propane/n-Hexane Binary Mixtures