Page 45 - Gas Adsorption Equilibria
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1. Basic Concepts 31
4. CHARACTERIZATION OF POROUS SOLIDS
The porosity or pore system of a porous sorbent material can be
characterized in many different ways. The most important physical methods
and their ranges of application, i. e. the range of diameter of cylindrical pores
or width of slit like pores, are listed in Table 1.4, [1.42]. The basic physical
principle of all of these methods is the same: one chooses a physical agent,
namely a probe or yardstick molecule or atom, or elementary particles like
neutrons, protons or photons of different wave length, i. e. energy and
momentum. Contacting the sorbent material to this agent, part of it will
interact with the material, i. e. either being absorbed or adsorbed or, as in case
of radiation, scattered or reflected in various directions and at various
energies. This provides a signal, imaging in a certain way the porous material
and allowing it to be characterized in comparison to other porous materials.
As extensive literature is available for all of the methods mentioned in
Table 1.4 [1.1-1.3, 1.26, 1.29, 1.42] we do not consider them here in more
detail but restrict the discussion only to those which are the most important
for characterization of sorbent materials for industrial purposes:
