Thermodynamics of hard-sphere fluids in polydisperse random porous media: Extended scaled particle theory

TL;DR

This paper develops an analytical scaled particle theory to describe the thermodynamics of polydisperse hard-sphere fluids in porous media, matching simulations across various parameters.

Contribution

It extends existing scaled particle theory to higher matrix packing fractions and polydispersity, providing a comprehensive analytical framework.

Findings

Excellent agreement with Monte Carlo simulations.

Accurate chemical potentials across a broad parameter range.

Extended the theory to higher matrix packing fractions.

Abstract

Accurate descriptions of reference systems are a central task in liquid-state theories for the study of more complex systems. Using scaled particle theory (SPT), we derive a fully analytical description of the thermodynamic properties of a hard-sphere (HS) fluid confined in size-polydisperse HS random porous media, extending the existing approaches to higher matrix packing fractions. We calculate chemical potentials for a wide range of porous-matrix parameters, including the matrix packing fraction, degree of polydispersity, and particle-size distributions. Within the proposed framework, our results show excellent agreement with available Monte Carlo simulations and previous integral-equation theories over a broad range of matrix packing fractions, $0.1 \leqslant \eta_0 \leqslant 0.3$, and degrees of polydispersity.