Experimental and modeling study of adsorption in preparative monolithic silica column

The hydrodynamic, equilibrium and kinetics of adsorption in a silica-based monolithic preparative column Chromolith Prep. Si (Merck KgaA, Germany) have been studied. The inverse size-exclusion chromatography with polystyrene standards of narrow molecular size distribution and small tracer molecule has been used to measure the external and total porosity of the monolithic column. The column permeability was calculated according to the Darcy law for laminar flow. The efficiency of the monolithic column was characterized through the height equivalent to a theoretical plate (HETP) of phenol, ethyl vanillin and dimethyl phthalate. The separation efficiency does not decrease in the region of high flow rates. The adsorption isotherms of phenol, ethyl vanillin and dimethyl phthalate measured by frontal analysis were linear in the investigated concentration range. The 2D single channel mathematical model has been applied to describe the adsorption dynamics. The model assumes parabolic velocity profile, axial and radial diffusion in the monolith channel, linear driving force model for the mass transfer in the monolith channel skeleton wall and linear adsorption equilibrium. The model gives good prediction of the experimental breakthrough curves.