ADSORPTION CHARACTERISTICS OF CRESOLS WITH ELUENT COMPOSITION IN ADSORPTION CHROMATOGRAPHY

Abstract

Adsorption characteristics of cresol isomers in adsorption chromatography were investigated in a system where the binary eluent containing ethyl acetate as a modifier in n-hexane was used. The method of moments was used to estimate the equilibrium constant and the rate parameters. The agreement between the experimental and theoretical results calculated by the orthogonal collocation method was excellent. The equilibrium constant and rate parameters for each cresol were empirically correlated with eluent composition. As the eluent composition increased, the retention time and the front of the response curve became faster and sharper, respectively. By using the modifier in a weak solvent, mixtures of o-/m-cresols and o-/p-cresols were easily separated whereas that of m-/p-cresols was not. The values on the scale of axial eddy dispersion were much larger than those of the gas system. For o-cresol, these values diminished with increasing eluent composition, while for m- and p-cresols the trend was reversed. For all systems, both intraparticle mass transfer and axial dispersion were dominant.