where Ce is the equilibrium concentration of the adsorbate (mg/L),
qe is the amount of adsorbate per unit mass of adsorbent (mg/g) at
equilibrium, KF is Freundlich constant, and n is an indicator for
occurrence of adsorption process. KF ((mg/g) (L/mg) 1/n) is related to
adsorption capacity of the adsorbent.