Description of the Adsorption Equilibrium with Consideration to the Decreasing Availability of Space in the Course of Mobile Adsorption of a Single Gas on a Homogenous Surface of Solid

The subsequent stages of the process of formulation of the equation for gas adsorption on a homogenous surface of a solid adsorbent were presented based on the general expression for the canonical ensemble of the mobile single-component adsorption monolayer. The method of formulating the configuration integral of the proposed model was discussed in detail where the role both of the attraction and repulsion between adsorbed molecules was emphasised. The expression for the probability of finding a molecule in a specified point on a surface of an adsorbent was modified by determining its magnitude by the adsorbent concentration. The expression for the so-called effective surface of the adsorbent was obtained by adapting a two-dimensional analogue equation of state hard spheres – Van der Waals equation (2D-vdW) and Reis-Frisch-Lebowitz equation accordingly (2D-RFL). As a result, two new adsorption equations were formulated which differ in detail concerning the adsorbate-adsorbate repulsion. On each of these equations theoretical analysis was performed in terms of two-dimensional phase transformation. In both cases it was proved that the proposed solution allows for the presence of two-phase transformations of the first type which is the gas-liquid condensation and solidification liquid-solid. The verification of the given approach was supplemented by the description of the experimental data given in reference literature and by obtaining a very good correlation between the theory and experiment.

Energetic Topography in Adsorption onto Heterogeneous Surfaces

The adsorption of gases onto heterogeneous surfaces has been reviewed, highlighting models capable of taking energetic topography effects into account. The basic ideas are contained in the fundamental Generalized Gaussian Model (GGM) developed to represent mobile adsorption onto heterogeneous surfaces at low coverage, where the energetic topography is considered through an adsorptive energy distribution with a spatial correlation function. Adsorbate molecules interact amongst them via Lennard-Jones interactions. Model predictions have been compared to Monte Carlo simulations of adsorption onto heterogeneous solids obtained by doping a pure crystalline solid with different concentrations of impurities. Energetic topography effects were shown to be important, being predicted correctly by the model at low coverage. In addition, a simplified patchwise model was also considered. The adsorption of particles with nearest-neighbour attractive and repulsive interactions was studied using Monte Carlo simulation on bivariant surfaces characterized by patches of weak and strong adsorbing sites of size “i”. Patches were considered to have either a square or a strip geometry, arranged either in a deterministic ordered structure or in a random way. Quantities have been identified which scale obeying power laws as a function of the scale length “l”. The consequences of this finding for the determination of the energetic topography of a surface from adsorption measurements were discussed.

Predictions of adsorption behaviour of the heaviest elements in a comparative study from the electronic structure calculations

SummaryThermodynamics of adsorption of gaseous species on the surface of a gas chromatography column is considered using the knowledge of the electronic structure of the adsorbate. Relevant equations based on a model of mobile adsorption are offered to predict the adsorption temperature,

Stochastic Properties of the Solution Vector of Parameters for the Model of the Partially Mobile Adsorption of a Single Gas on an Energetically Heterogeneous Microporous Adsorbent

For the previously formulated model of single gas adsorption on energetically heterogeneous microporous solids, two adsorption isotherms were generated — one for each distribution function of the localization energy dividing two neighbouring adsorption sites. Using numeric methods, a mass measurement error was ascribed to each point generated for both adsorption isotherms and an analysis of the influence of the normal distribution of this error on the type of distribution of the optimized parameter values was undertaken. The hypothesis regarding the agreement of the distributions of the parameter values for both energy distribution functions was verified. The work described was carried out for three arbitrary assumed values of the variation coefficients of the adsorbate mass measurement error.

Adsorbate—Adsorbate Association in a One-Component Mobile Adsorption Phase on Energetically Homogeneous Adsorbents

A new description of adsorbate-adsorbate association on energetically homogeneous adsorbents has been presented. Suitable relations have been formulated for the mobile adsorption of a single gas. Experimental adsorption data have been described theoretically by the equations derived. The calculation results demonstrate the good applicability of the proposed idea.