Liquid-phase Adsorption from Binary Solutions on Silica Gel. The Apparent Separation Factors and the Distribution of Adsorption Sites

• Published in: Bulletin of the Chemical Society of Japan Vol. 45; no. 6; pp. 1643 - 1648
• Main Authors: Kagiya, Tsutomu, Sumida, Y\={u}z\={o}, Tachi, Toshihiro
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 01.06.1972; Chemical Society of Japan
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.45.1643

The liquid-phase adsorption equilibrium of a cyclohexane-benzene mixture on a silica-gel surface, containing various quantities of physically-adsorbed water, has been studied at 30°C. The apparent separation factors (αap) have been determined on the assumption that this liquid-phase adsorption is of the Langmuir-type. It was found that the values of αap were, in general, markedly affected not only by the composition of binary solvents, but also by the amounts of physically-adsorbed water. In order to discuss this point quantitatively, the theoretical equation for estimating the apparent separation factors on a complicated solid surface having two or more types of adsorption sites has been derived on the basis of the theory of chemical equilibrium. The following three types of adsorption sites have been assumed to exist on the silica-gel surface used in this experiment: the surface silanol (σ1), the monolayer of water (σ2), and the multilayer of water (σ3). The separation factors of the σ1 and σ3 were experimentally measured as 17.1 and 2.5. By best-fitting the above theoretical equation for αap with the observed values, the separation factor of the σ2 site was taken to be 3.7 and the distribution of each adsorption site on the surface was determined.