The essential features of Langmuir isotherm can be expressed by the dimensionless constant separation factor or equilibrium parameter: RL = 1/(1 + KLCo), where KL is the Langmuir isotherm constant, and Co represents the initial Fe2+-ions concentration in the study aqueous medium [21]. The values of RL calculated for Fe(II) ad-sorption on to FeOOH coated-brick pellets were found to be, in all cases, within 0 and 1, suggesting a highly fa- vorable adsorption process, in addition, with a more ele- vated adsorption efficiency when Fe(II) content increased in solution [raw brick pellets: 0.14 ≤ RL ≤ 0.68; and pre-treated (activated) brick : 0.04 ≤ RL ≤ 0.08].