Vapour-liquid phase diagram for an ionic fluid in a random porous medium
| Autor: | Oksana Patsahan, T. Patsahan, M. F. Holovko |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Materials science
Statistical Mechanics (cond-mat.stat-mech) Ionic bonding Thermodynamics FOS: Physical sciences 02 engineering and technology Hard spheres Condensed Matter - Soft Condensed Matter 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Ion Matrix (mathematics) Critical point (thermodynamics) 0103 physical sciences Soft Condensed Matter (cond-mat.soft) General Materials Science 010306 general physics 0210 nano-technology Porous medium Porosity Condensed Matter - Statistical Mechanics Phase diagram |
| Zdroj: | Journal of physics. Condensed matter : an Institute of Physics journal. 28(41) |
| ISSN: | 1361-648X |
| Popis: | We study the vapour-liquid phase behaviour of an ionic fluid confined in a random porous matrix formed by uncharged hard sphere particles. The ionic fluid is modelled as an equimolar binary mixture of oppositely charged equisized hard spheres, the so-called restricted primitive model (RPM). Considering the matrix-fluid system as a partly-quenched model, we develop a theoretical approach which combines the method of collective variables with the extension of the scaled-particle theory (SPT) for a hard-sphere fluid confined in a disordered hard-sphere matrix. The approach allows us to formulate the perturbation theory using the SPT for the description of the thermodynamics of the reference system. The phase diagrams of the RPM in matrices of different porosities and for different size ratios of matrix and fluid particles are calculated in the random-phase approximation and also when the effects of higher-order correlations between ions are taken into account. Both approximations correctly reproduce the basic effects of porous media on the vapour-liquid phase diagram, i.e., with a decrease of porosity the critical point shifts toward lower fluid densities and lower temperatures and the coexistence region is getting narrower. For the fixed matrix porosity, both the critical temperature and the critical density increase with an increase of size of matrix particles and tend to the critical values of the bulk RPM. Comment: 22 pages, 7 figures |
| Databáze: | OpenAIRE |
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