Solute or sorbate within the packed section of a column can be in one of three locations. The solute can be in the interstitial void space εe and be moving at the interstitial velocity vinter. If the solute is in the intraparticle voids (1 − εe)εp or sorbed to the stationary solid it will have a net axial velocity of zero. In other words, the solute molecules are either scooting forward axially at a high velocity (remember that vinter is greater than vsuper), or they aren’t moving at all. The average solute velocity us is
This fraction can be calculated by considering the distribution of an ...