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Publisher Summary The surface characteristics of inorganic solids are commonly measured by adsorption of gases and vapors which is normally carried out in a wide range of vapor pressures from low to high relative pressures (in many cases up to P/PO =1). From these measurements, average values of pore radius and surface energy are obtained. This is very useful for many purposes, for example, when solids are used as adsorbents in gas and liquid phases or as supports for catalysts. However, in several cases, the concentration of substance to be adsorbed is very small and the adsorption process is not governed by the bulk textural properties of the solid. This occurs in the emission of fluent gases from car engines and industrial processes. For this reason, it is not possible to explain the adsorption of one diluted adsorbate on the basis of the bulk surface properties of the adsorbent. This can be explained, however, by studying the surface characteristics on the basis of the adsorption at very low vapor pressure of the adsorbate at the so called zero surface coverage, where the amount adsorbed depends linearly on the vapor pressure (Henry's law region). For this purpose, gas solid chromatography is a technique which is increasingly used. Gas solid chromatography is an analytical technique used for many purposes. However, its use to obtain information about characteristics of the stationary phase is less common, and in this case is called inverse gas chromatography (IGC). |
