Page 184 - Introduction to Colloid and Surface Chemistry

The solid-liquid interface 173
adsorbed molecule is known, the specific surface area of the solid can
be calculated as described on page 134-36 for gas adsorption.
Adsorption from solution has the merit of being experimentally
less demanding than gas adsorption; however, the problems in
interpretation are far greater.
Since relatively large and asymmetric adsorbate molecules, such as
moderately long-chain fatty acids and various dyestuffs, are usually
involved in adsorption from solution, it is necessary to make
assumptions regarding their orientation and packing efficiency in
calculating their effective surface coverage. In view of the uncertainties
involved in such calculations, it is usually desirable to calibrate a
particular adsorption from solution system with the aid of a surface
area determined by a less complex method, such as nitrogen
adsorption. Adsorption from solution can then provide a convenient
technique for determining specific surface areas.