Adsorption and interfacial phenomena of a Lennard-Jones fluid adsorbed in slit pores: DFT and GCMC simulations

ABSTRACT

Confinement of fluids in porous media leads to the presence of solid–fluid (SF) interfaces that play a key role in many different fields. The experimental characterisation of SF interfacial properties, in particular the surface tension, is challenging or not accessible. In this work, we apply mean-field density functional theory (DFT) to determine the surface tension and also density profile of a Lennard-Jones fluid in slit-shaped pores for realistic amounts of adsorbed molecules. We consider the pore walls to interact with fluid molecules through the well-known 10-4-3 Steele potential. The results are compared with those obtained from Monte Carlo simulations in the Grand Canonical Ensemble (GCMC) using the test-area method. We analyse the effect on the adsorption and interfacial phenomena of volume and energy factors, in particular, the pore diameter and the ratio between SF and fluid–fluid dispersive energy parameters, respectively. Results from DFT and GCMC simulations were found to be comparable, which points to their reliability.

GRAPHICAL ABSTRACT

KEYWORDS:

• Density functional theory
• Monte Carlo simulation
• interfacial tension
• test-area
• adsorption

Acknowledgements

The authors would like to acknowledge helpful discussions with A. I. Moreno-Ventas Bravo. We also acknowledge Centro de Supercomputación de Galicia (CESGA, Santiago de Compostela, Spain) and MCIA (Mésocentre de Calcul Intensif Aquitain) of the Universités de Bordeaux and Pau et Pays de l'Adour (France), for providing access to computing facilities.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

F. J. Blas  http://orcid.org/0000-0001-9030-040X

Additional information

Funding

The authors would like to acknowledge Ministerio de Economía y Competitividad through Grants with references FIS2015-68910-P and (Secretaría de Estado de Investigación, Desarrollo e Innovación) FIS2015-71749-REDT and Ministerio de Economía, Industria y Competitividad through Grant with reference FIS2017-89361-C3-1-P, all three co-financed by EU FEDER funds. Further financial support from Junta de Andalucía and Universidad de Huelva is also acknowledged.