SOLVENT CONCENTRATION EFFECTS ON SORPTION AND DIFFUSION OF CRESOLS INBETA-CYCLODEXTRIN-SILICAS

A chromatographic technique was used to experimentally study the effec ts of solvent concentration on sorption and diffusion of cresols in a bonded beta-cyclodextrin-silica with a mixed solvent of methanol and w ater as mobile phase. A distribution model that accounts for the non-i deality caused by the different degrees of interaction with the statio nary phase for the solute and solvent components was proposed, based o n the mechanism of multi-component competitive adsorption, to describe the solvent concentration dependence of the distribution coefficient. The results showed that the distribution model is in good agreement w ith the experimental data. The axial dispersion, external film mass tr ansfer and intraparticle diffusion were found to be dependent on the s olvent concentration. An analysis of the solvent concentration effect on the intraparticle diffusion in the range of 33.3 mol/l less-than-or -equal-to c1 less-than-or-equal-to 49.95 mol/l indicated that the effe ct of solvent concentration on restricted diffusion is large in compar ison with the solvent concentration effect on non-restricted diffusion for each cresol.