Zone 1. The primary function of this zone is to adsorb A from the liquid.
Zone 2. The primary function of this zone is to remove B from the pores of the solid
Zone 3. The function of this zone is to desorb A from the pores
Zone 4. The purpose of this zone is to act as a buffer to prevent component B, which is at the bottom of
Zone 1, from passing into Zone 3, where it would contaminate extracted component A.