Page 315 - Adsorption by Powders and Porous Solids
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ADSORPTION BY POWDERS AND POROUS SOLIDS
Figure 10.8. Nitrogen isotherms (top) and a,-plots (bottom) for mesoporous silica gels A, J and G
(from Bhambhani et al., 1972).
As explained in Chapter 8, the extemal surface area, a(ext, S), available for multi-
layer adsorption can be calculated from the highp/pO section of an a,-plot, provided
that there is an adequate range of linearity to confii the absence of capillary con-
densation. This condition is clearly fulfilled with gels D and E, and their external
areas are therefore recorded in Table 10.8.
