Mass-transfer rates in chromatographic separations

The separation of multicomponent mixtures into more than two products usually requires more than one separation device. Chromatography is one of the few separation techniques that can separate a multicomponent mixture into nearly pure components in a single device, generally a column packed with a suitable sorbent. The degree of separation depends upon the column length and the differences in component affinities for the sorbent used. 

For each of the n solutes in the feed, neglecting axial dispersion and assuming a constant interstitial velocity, equations (9-49) and (9-50) apply. The boundary conditions, however, are different from those of adsorption in a fixed bed. In this case, periodic injections of rectangular feed pulses of duration tF are followed by elution periods of duration t . Then, for the first feed pulse the boundary conditions are Initial condition  

For the case of linear adsorption isotherm, the system of equations (9-49) and (9-50) with boundary conditions (9-67) to (9-69) have been solved assuming no interaction between the solutes (Vermeulen et al., 1973)  

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