INFLUENCE OF ADSORPTION ON THE MEASUREMENT OF DIFFUSION-COEFFICIENTS BY TAYLOR DISPERSION

The effect of adsorption on the measurement of diffusion coefficients by the Taylor dispersion technique is investigated by modifying the go verning equation to account for reversible, nonequilibrium adsorption. The resulting two-dimensional equations are solved by an explicit fin ite-difference technique. Experimental data for the acridine-carbon di oxide system indicated that acridine adsorbs on the walls on the tubin g and these data were investigated with this model. The influence of v arious parameters including the number of sites and the rates of adsor ption/desorption was investigated by conducting a parametric sensitivi ty analysis on the model. It was found that adsorption of the solute o n the wall of the tubing could produce an error as high as 35% on the measured diffusion coefficient compared to the actual diffusion coeffi cient. Examination of the influence of each of the parameters will ena ble future investigators to reduce the effect of adsorption in the mea surement of diffusion coefficients by Taylor dispersion.