THE ADSORPTION OF DIOXAN BY POROUS SILICAS

Volumetric adsorption of nitrogen and gravimetric adsorption of dioxan is reported for nonporous, mesoporous, and microporous silicas. Adsor ption on the microporous material is governed by pore volume and dimen sions. Adsorption on the nonporous silica and the mesoporous silica at up to monolayer coverages is governed by specific hydrogen bonding in teractions between surface silanol groups and dioxan molecules. Differ ent silanol group distributions for different silicas after standard t reatment coupled with different possible modes of adsorption casts dou bt on the use of nonporous silica as a standard for the study of inter actions between porous silicas and H-bond acceptor molecules. (C) 1996 Academic Press, Inc.