Adsorption general molecular statistics

Equations should be selected or a new more general equation developed which have a molecular-statistical basis and describe the relationships between the amount of adsorption, the heat of adsorption, the heat capacity of the system, the pressure, and the temperature. Various constants in these equations must have a clear physical meaning. These equations must describe the exact shape of the isotherms (Figure 2) and must reduce to the Henry equation at low coverage. 

Theoretical molecular statistic calculations of adsorption thermodynamic properties for colloid systems are generally believed to be a quite cumbersome problem. This is mainly... 

An approximate analysis of polymer adsorption as a set of sequential reactions leads to a simple equation for the adsorption isotherm expressed in terms of three parameters. Comparison of the model with recently published statistical theories reveals remarkable agreement in both the general shape of the isotherms and the predicted effects of molecular weight. The problems of applying such models to experimental data are discussed. 

With nonpolar sorbates an increase in heat of adsorption with coverage is commonly observed, as illustrated in Figure 4.5 and this is commonly attributed to the effect of intermolecular attraction forces. The statistical model isotherm, however, suggests an alternative explanation. If the effective molecular volume increases with temperature, as it generally does, the isosteric heats... 

There are no expressions of equivalent reliability and generality for the contributions to Ui,(r) from steric interactions. A full understanding of steric stabilization requires further progress in the theory of physical adsorption of macromolecules. The problem is essentially a molecular one, and will not be discussed in this Report which is concerned with statistical mechanics at the particulate level. For the same reason, we are not concerned here with short-range solvent-mediated structural forces, which can become important when particles are very close together. 

A positive feamre about MPTA is that it has been generalized for several complex cases like liquid solutions, supercritical/high pressure and non-Langmuir adsorption behaviour. In addition, MPTA may probably be considered as a partial step from macroscopic , phenomenological adsorption theories towards the theories based on statistical mechanics and molecular dynamics, like, for example, density functional theory. 

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