Interfacial properties of hydrocarbon/water systems predicted by molecular dynamic simulations

Naeiji, Parisa; Woo, Tom K.; Alavi, Saman; Varaminian, Farshad; Ohmura, Ryo

doi:10.1063/1.5078739

Cited by 33 publications

(21 citation statements)

References 34 publications

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“…Thus, for a rigorous determination of g one should include long range corrections (LRC) [131e134] which give a positive contribution to g. We have implemented the methodology of Lundberg and Edholm [134] and estimated this correction to be about 2 mJ/m 2 for the methane-water interface (the thickness of the interface was 0.28 nm and the magnitude of the dispersion density difference squared was ðDr C6 Þ 2 Â 10 20 ¼ 0:15 J). This is in line with the small value of the correction found by Naeiji et al [135]. The values obtained after including the LRC correction are presented in Table 4.…”

Section: Resultssupporting

confidence: 89%

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Scaled charges at work: Salting out and interfacial tension of methane with electrolyte solutions from computer simulations

Blazquez

Zerón

Conde

et al. 2020

Fluid Phase Equilibria

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The solubility of methane in water decreases when a small amount of salt is present. This is usually denoted as the salting out effect (i.e., the methane is expelled from the solution when it contains small amounts of salt). The effect is important, for instance the solubility is reduced by a factor of three in a 4 m (mol/kg) NaCl solution. Some years ago we showed that the salting out effect of methane in water can be described qualitatively by molecular models using computer simulations. However the salting out effect was overestimated. In fact, it was found that the solubility of methane was reduced by a factor of eight. This points to limitations in the force field used. In this work we have carried out direct coexistence simulations to describe the salting out effect of methane in water using a recently proposed force field (denoted as Madrid-2019) based on the use of scaled charges for the ions and the TIP4P/2005 force field for water. For NaCl the results of the Madrid-2019 force field significantly improve the description of salting out of methane. For other salts the results are quite reasonable. Thus the reduction of the charge of the ions also seems to be able to improve the description of salting out effect of methane in water. Besides this we shall show that the brine-methane interface exhibits an increased interfacial tension as compared to that of the water-methane system. It is well known that electrolytes tend to increase the surface tension of liquid water, and this seems also to be the case for the interface between water and methane.

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Section: Resultssupporting

confidence: 89%

“…6 right) using the Madrid-2019 force field to describe the water-ion interaction. Notice that the methane molecule presents positive adsorption at the water-gas interface both for pure water and for the solution as was also found in previous work ( [135,139]). Methane also shows positive adsorption when salt is added to the solution.…”

Section: Resultssupporting

confidence: 86%

Scaled charges at work: Salting out and interfacial tension of methane with electrolyte solutions from computer simulations

Blazquez

Zerón

Conde

et al. 2020

Fluid Phase Equilibria

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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%

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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“…This is because there is no well-defined gas−liquid interface as described in thermodynamics (Gibbs' dividing plane) at this scale; 31 instead, there is a sub-nanometer-thick region in which the molecular density changes continuously, as is often observed in MD simulations. 32 Therefore, it would be difficult to apply the thermodynamic definition of the contact angle at this scale, which considers the gas−liquid interface to be a definite surface. Also, we would like to clarify that the size of these nanoparticles (∼2 nm) is not the threshold for pinning caused by structural inhomogeneity because its strength is determined not only by structural heterogeneity but also by chemical heterogeneity, which may be significantly large between the metal particle and the graphene.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Pinning in a Contact and Noncontact Manner: Direct Observation of a Three-Phase Contact Line Using Graphene Liquid Cells

et al. 2021

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Pinning of a three-phase contact line at the nanoscale cannot be explained by conventional macroscale theories and thus requires an experimental insight to understand this phenomenon. We performed in-situ transmission electron microscopy observation of the three-phase contact lines of bubbles inside graphene liquid cells to experimentally investigate the causes of nanoscale pinning. In our observations, the three-phase contact line was not affected by the 0.6 nm-thick inhomogeneity of the graphene surface, but thicker metal nanoparticles with diameters of 2–10 nm and nanoflakes caused pinning of the gas–liquid interface. Notably, we found that flake-like objects can cause pinning that prevents the bubble overcome the flake object in a noncontact state, with a 2 nm-thick liquid film between them and the bubble. This phenomenon can be explained by the repulsive force obtained using the Derjaguin, Landau, Verwey, and Overbeek theory. We also observed that the flake temporally prevented the gas–liquid interface moving away from the flake. We discussed the physical mechanism of the attractive force-like phenomenon by considering the nanoconfinement effect of the liquid sandwiched by two graphene sheets and the hydration layer formed near the solid surface.

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Interfacial properties of hydrocarbon/water systems predicted by molecular dynamic simulations

Cited by 33 publications

References 34 publications

Scaled charges at work: Salting out and interfacial tension of methane with electrolyte solutions from computer simulations

Scaled charges at work: Salting out and interfacial tension of methane with electrolyte solutions from computer simulations

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

Pinning in a Contact and Noncontact Manner: Direct Observation of a Three-Phase Contact Line Using Graphene Liquid Cells

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