Effect of repulsive and attractive interactions in the adsorption of confined polydisperse fluids

Abstract

A density functional perturbative approximation, which is based on the pair distribution function, has been developed to investigate the influence of attractive and repulsive interactions on the density behaviour of a confined polydisperse fluid. The calculated result shows that the attractive and repulsive interactions in the model potential are strongly affected on the adsorption of a confined polydisperse fluid as well as the cavity size and particle size ratio. The attractive interaction in a polydisperse square-well system increases the pore average mole fraction for small particles in a circular cavity. Whereas a repulsive interaction in a polydisperse square-shoulder system decreases the pore average mole fraction for small particles. The local relative concentration oscillates with a spatial period close to the diameter of a large particle as well as the equilibrium density distribution does.

Theory of adsorption in a polydisperse templated porous material: Hard sphere systems

“…Obviously, higher porosity lowers matrix-fluid correlations. Moreover, polydispersity of the porous medium also causes smoothing of the correlation function-previous calculations carried out for uniform, 32,33,36 as well as for nonuniform fluids 35,37,38 indicated that the structure of a polydisperse fluid is less pronounced than the structure of a monodisperse fluid having the same total density. Figures 4͑b͒ and 4͑c͒ also show the correlation functions between templates ͑''empty sites'' of a given size͒ and fluid particles.…”

Entropic selectivity of microporous materials

“…V av (a), If the FMT expressions ((B6)È(B8)) for the one-particle direct correlation functions are substituted into eqn. (14), c a (1) one obtains a set of highly non-linear and non-local equations for the unknown density proÐles, which must be solved iteratively, for any given set of chemical potentials subject to Mk a N, the boundary conditions (10) or (11). This is achieved on a Ðne 1d grid, using a Picard iterative procedure,23 which must be repeated for each composition of the bulk mixture, i.e.…”

“…The actual density of interacting spheres is given by eqn. (14), where is a negative function of r for hard sphere c a…”

“…is the one-particle direct correlation function of species a in the conÐned Ñuid.17 The FMT expression for is given in Appendix B. k a ex. c a (1) The expression (14) holds for any r inside the available volume and is supplemented by the constraints (9). V av (a), If the FMT expressions ((B6)È(B8)) for the one-particle direct correlation functions are substituted into eqn.…”

Effective interactions in polydisperse colloidal suspensions investigated using Ornstein–Zernike integral equations

“…Pagonabarraga et al [32] extended fundamental measures' theory to polydisperse hard-sphere fluids. This, and similar approaches were subsequently applied to investigate various confined polydisperse colloidal systems such as hard walls or idealized semipermeable membranes [33][34][35][36].…”