The Characterization of Physical Adsorption Systems. I. The Equilibrium Function and Standard Free Energy of Adsorption

Abstract

Secondly, the authors state, ".. .we should expect, on the basis of polylayer for mation, decreasing adsorption with decreasing porosity also in the case of imperfect contacts,..." I do not agree that this should be expected. The real contacts of 3-mm. diameter spheres would not appreciably affect the building up of a few adsorbed layers because these few layers would require only a few angstrom units of depth. The authors' results may be interpreted in terms of capillary condensation, but they do not rule out the possibility of multilayer formation.

Adsorption of alkali chloride and ammonium halide on halloysite

“…The strict application of the equation (4) to the present adsorption of ionic compounds is somewhat questionable in view of the adsorbate interaction, but it Jl'lay provide an approximate measure of the strength of the adsorption bond. The obtained values for -LlF O are of the order of 250 to 800 cal per mole (Table 3), and are comparable to those for VAN DER WAALS adsorption of gas molecules on solid surface (2). It constitutes a good evidence that no electrostatic interaction contributes at least mainly to the bonding of the ions to the kaolin layers.…”

Sorption of Boron by Hydrous Al-Oxide

“…In Figure 8 In K values obtained at different temperatures are plotted as a function of 1/T. As seen from the figure a straight line is obtained, thus demonstrating a behavior similar to a real equilibrium constant (Graham 1953). Furthermore, the slope of the line in Figure 8 gives a value of -10.7 kJ mol-'; a value similar to the enthalpies of physical adsorption reactions.…”

Metal-Induced Sulfate Adsorption by Soils

“…An equation similar to the Langmuir equation can be derived from adsorption equilibria (Graham, 1953):…”