Brick which originated from Bangui Region (in Central African Republic), was pre- activated with HCl at 90°C and coated with ferihydrite. This material was used in the
present work as an adsorbent mainly for the removal of metalic cations (Me2+ = Cd2+;
Cu2+; Pb2+; Zn2+) from aqueous solutions due to their bad efect on the environment.
Experimental results were compared to those obtained for other divalent cations (Ca2+
, Fe2+, Mg2+, Mn2+, Sr2+). Freundlich and Langmuir models were aplied to describe
adsorptions isotherms, and Langmuir model was found to provide the best fiting.
Langmuir adsorption capacites (Qmax) of these ions onto ferihydrite-coated brick
increased in the folowing order: Cu > Zn >Pb>Ca> Cd >Mg. Kinetic studies revealed that
experimental data were beter fited by the pseudo second-order rate equation than the
pseudo first-order rate one. Thermodynamic analyses indicated that the adsorption
kinetics proces was endothermic. Because of acid/hydrolysis characteristics of metalic