Where C is the equilibrium concentration of the ARS solution (mg L) is the adsorption capacity at equilibrium (mg ) is the constant related to free energy of adsorption (L mg ) and is the maximum adsorption capacity at manolayer coverage (mg ) The Freundlich isotherm is an empirical equation that assumes heterogeneous adsorbent surface with its adsorption sites at varying energy levels [40]. The corresponding equations are commonly represented by: . . K (mg) and n are the Freundlich constants character istics of the system, indicating the adsorption capasiry and the