is the assimilation of one material into another; in petroleum refining, the use of an absorptive liquid to selectively remove components from a process stream.

is a physical process not accompanied by any other physical or chemical process, it usually follows the Nernst partition law:

"the ratio of concentrations of some solute species in two bulk phases in contact is constant for a given solute and bulk phases"

The value of constant K_N depends on temperature and is called partition coefficient. This equation is valid if concentrations are not too large and if the species "x" does not change its form in any of the two phases "1" or "2".

Also see:  adsorption, hydroscopic.