Adsorption equilibria of butyl- and amylbenzene on monolithic silica-based columns

The adsorption isotherms of butyl- and amylbenzene on silica monolithic columns were measured by frontal analysis. The external, internal and total porosities of these columns were determined by inverse size-exclusion chromatography. The adsorption isotherms are concave upward in the entire concentration range investigated. They were fitted to the anti-Langmuir model, an unusual model in liquid–solid and liquid–liquid phase equilibria. Band profiles under overloaded conditions were recorded. They were in good agreement with the profiles calculated using the lumped pore diffusion model of chromatography and these adsorption isotherms.