Abstract

This work deals with the removal of heavy metals from wastewater which presents a major ecological problem. Recently, this has been solved by using adsorption techniques as a means to extract heavy metal ions. The present investigation was carried out on the adsorption of heavy metals from single and binary component aqueous solutions on activated carbons. The concentrations of heavy metals ions, Ni(II) and Pb(II), ranged from 10 to 100 mg.L^-1 and 10 to 200 mg.L^-1, respectively. A microporous KOH-activated carbon and a commercial mesoporous carbon were used. The first part focuses on the adsorption equilibrium of single-component metal ions solution. The KOH-activated carbon showed better performance for removal of both ions than H₃PO₄-activated carbon. The second part deals with adsorption competition between the two metals ions. The adsorption of each respective ion in a mixture was decreased compared to the single-component metal ions. Both activated adsorbents showed higher affinity for Pb(II) ions than for Ni(II) ions. The adsorption of both metal ions on adsorbents was modelled by applying Langmuir models. In addition, it has been found that the percent removal of both metallic ions is strongly concentration dependent; for low initial concentration of Ni(II) and Pb(II) it reaches 98%, while for higher initial concentrations the percent removal drops up to 78% with better performance for CKW-activated carbon.

Key words: Activated carbon, Nickel, Lead, adsorption, binary adsorption, Langmuir, affinity.