Adsorption equilibria for Cresol isomers onto silica gel in n-hexane were investigated in the concentration range of 1-30 mol/$m^3$. The affinity with respect to silica gel decreased in sequence of p-, m-, o-Cresol in single component system. The model presented by Jain and Snoeyink well predicted the experimental results in the group used only the isotherm parameters of single component system. And the model proposed by Fritz and Schlunder had the lowest average percent deviations in the group used binary experimental data. The adsorbed amounts of m-Cresol were more influenced by o-Cresol than those of p-Cresol. Thus the separability of m-/p-Cresol mixture became large as the concentration of o-Cresol increased and these phenomena were caused by inductive adsorption created by steric hindrance between coadsorbed molecules.
Adsorption characteristics of Cresol isomers were investigated by the single column chromatography packed with silica gel. The eluents were composed of n-hexane and ethyl acetate. Solvent composition instead of temperature could be used as a good driving force to separate a mixture. Equilibrium constant and rate parameters were obtained by the method of moments. The equlibrium constant and intraparticle mass transfer coefficient estimated for each component were empirically correlated with solvent compositions in an exponential function. The axial dispersion mass transfer resistance was significantly larger than the others. The agreement between the experimental and theoretical results calculated by orthogonal collocation method was excellent.
The criteria for maximizing throughput was developed in volumn overloading condition. To overcome the disadvantage in the conventional chromatography, the step gradient elution chromatography was applied and the model equation considered for all kinetic mechanisms in this operation method was developed. From this step gradient operation method, the more efficient elution than that of conventional chromatography was obtained.
