Molecular Dynamics Study of Adsorption of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

Heier, Michaela; Diewald, Felix; Horsch, Martin; Langenbach, Kai; Müller, Ralf; Hasse, Hans

doi:10.31219/osf.io/v9ujs

Cited by 3 publications

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“…Our interest is on elucidating the influence of the dispersive interactions in the system on the adsorption for a wide range of conditions. The present study extends our previous one on the adsorption of pure components on planar walls in the same systems 23 to binary mixtures. Symmetric as well as asymmetric mixtures were studied.…”

Section: ■ Introductionsupporting

confidence: 81%

“…The results for mixture I were adopted from our previous work on pure component adsorption. 23 For mixture II, a homogeneous azeotrope is observed. A reduction in temperature or an increase in pressure may lead to a miscibility gap or to solidification, which is, however, not further investigated here.…”

Section: ■ Introductionmentioning

confidence: 96%

“…In previous studies on adsorption and wetting of pure LJTS fluids in the same type of dispersive systems, 21,23 we have studied how the contact angle is related to the adsorption via the solid−fluid interaction. On the basis of these results, in the present study, the solid−fluid interaction parameters were chosen in such a way that for the pure component A, the following values of the contact angle are observed: θ = 175°for ε sA = 0.35 ε A , θ = 90°for ε sA = 0.514 ε A , and θ = 34°for ε sA = 0.65 ε A .…”

Section: ■ Introductionmentioning

confidence: 99%

“…A solid LJTS wall was obtained by choosing ε s = 100 ε A , as in previous studies. 17,21,23,28,49 The solid particles were arranged in a face-centered cubic (fcc) lattice with the (100) surface exposed to the fluid; the lattice constant was a = 1.55 σ. All wall particles took part in the simulation; the crystal configuration remained unchanged in all simulations, due to the high energy parameter of the solid.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The surface of the wall is in the x,z-plane of a Cartesian coordinate system, the y-axis is, hence, perpendicular to the surface. The wall was fixed at the bottom of the simulation box analogous to previous studies of Heier et al 23,49 Further information on the fixation is given in the Supporting Information. The wall consisted of six layers of LJTS-sites, that is, it is thicker than the cutoff radius of r c = 2.5 σ.…”

Section: ■ Introductionmentioning

confidence: 99%

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Adsorption of Binary Mixtures of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

et al. 2021

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Gas phase adsorption of binary mixtures on planar walls in dispersive systems was studied by molecular dynamics simulations, extending a previous study on the adsorption of pure components. The interactions between all particles, fluid as well as solid, were described by the Lennard-Jones truncated and shifted potential with a cutoff radius of 2.5 σ. Two classes of fluid mixtures were studied: (a) symmetric mixtures, in which the pure components and also their interactions with the wall particles are the same but the unlike fluid–fluid interaction parameter is varied; (b) an asymmetric mixture, in which the dispersive energy of one fluid component was lowered, such that it becomes light-boiling. For the asymmetric mixture, both nonselective walls as well as walls with different selectivity for the two fluid components were investigated. Data on the surface excess, the thickness, and the structure of the adsorbate layer as well as on the selectivity were measured. The results give insight into how adsorption of binary mixtures is influenced by the different dispersive interactions between the fluids and between the fluids and the wall.

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Section: ■ Introductionsupporting

confidence: 81%

Section: ■ Introductionmentioning

confidence: 96%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Adsorption of Binary Mixtures of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

et al. 2021

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Adsorption in Purely Dispersive Systems from Molecular Simulation, Density Gradient Theory, and Density Functional Theory

et al. 2019

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Adsorption is an important process used in many industrial unit operations. However, due to the heterogeneity of surfaces studied experimentally, it is not a simple task to evaluate the validity of theories for adsorption. Here, we present a thorough investigation of density functional theory and density gradient theory based on molecular simulation. While comparisons between these theories have been made in the literature, only our recently developed equation of state (EOS), the Perturbed Truncated and Shifted (PeTS) equation of state and the according functional version, allow a thorough validation of both theories, because the EOS separates repulsive and attractive free energy contributions consistently with the inhomogeneous theory. The PeTS EOS represents the thermodynamics of the Lennard-Jones truncated and shifted fluid with a cutoff radius of 2.5 times the fluid diameter very accurately and is valid in the metastable range, too. To check the validity of both density gradient and density functional theory in adsorption scenarios, molecular dynamics simulations are performed for several wall potentials common in adsorption calculations at various states and solid–fluid interaction energies. A new parametrization for the density functional theory is proposed that relies on bulk data for the pressure only. Adsorption is predicted well from this new theory in both gaseous and liquid states. In contrast, density gradient theory turns out to be valid only in the dilute gaseous regime if the parameters are not fitted to adsorption.

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Molecular Dynamics Study of Wetting and Adsorption of Binary Mixtures of the Lennard-Jones Truncated and Shifted Fluid on a Planar Wall

et al. 2021

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The wetting of surfaces is strongly influenced by adsorbate layers. Therefore, in this work, sessile drops and their interaction with adsorbate layers on surfaces were investigated by molecular dynamics simulations. Binary fluid model mixtures were considered. The two components of the fluid mixture have the same pure component parameters, but one component has a stronger and the other a weaker affinity to the surface. Furthermore, the unlike interactions between both components were varied. All interactions were described by the Lennard-Jones truncated and shifted potential with a cutoff radius of 2.5σ. The simulations were carried out at constant temperature for mixtures of different compositions. The parameters were varied systematically and chosen such that cases with partial wetting as well as cases with total wetting were obtained and the relation between the varied molecular parameters and the phenomenological behavior was elucidated. Data on the contact angle as well as on the mole fraction and thickness of the adsorbate layer were obtained, accompanied by information on liquid and gaseous bulk phases and the corresponding phase equilibrium. Also, the influence of the adsorbate layer on the wetting was studied: for a sufficiently thick adsorbate layer, the wall’s influence on the wetting vanishes, which is then only determined by the adsorbate layer.

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Molecular Dynamics Study of Adsorption of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

Cited by 3 publications

References 0 publications

Adsorption of Binary Mixtures of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

Adsorption of Binary Mixtures of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

Adsorption in Purely Dispersive Systems from Molecular Simulation, Density Gradient Theory, and Density Functional Theory

Molecular Dynamics Study of Wetting and Adsorption of Binary Mixtures of the Lennard-Jones Truncated and Shifted Fluid on a Planar Wall

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