Band Profiles of Two Components with the Ideal Model

We compare in Figure 11.7 the individual band profiles derived from the ideal model (solid lines) and those calculated with the equihbtium-dispersive model (dotted lines) in the case of two mixtures with relative compositions 1 3 and 3 1. The loading factors for the two components are Lf i = 1.2% and Lf i = 3.8%. The calculations with the equilibrium-dispersive model were made with efficiencies of 1000 (Figures 11.7a,c) and 5000 (Figure 11.7b,d). The apparent loading factors (m = N[k / 1+k see Eq. 10.115) for the two components range between 10 and 145. [Pg.543]

Prominent models for estimating peak profiles carry out a differentiation of the equilibrium isotherm with approximations for the mass transfer contribution. The equilibrium-dispersive model, above, assumes that all contributions due to nonequilibrium can be lumped into an apparent axial dispersion term. It further assumes that the apparent dispersion coefficient of the solutes remain constant, independent of the concentration of the sample components. For small particles, these approximations are reasonable for many applications. The ideal model assumes that the column efficiency is infinite. There is no axial diffusion, and the two phases are constantly at equilibrium. The band profiles obtained as solutions are in good agreement with experimental chromatograms for columns with N > 1000 having high loading factors. On the other... [Pg.869]

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