Removal of lead ions by Unye (Turkey) bentonite in iron and magnesium oxide-coated forms.

This paper presents the adsorption of Pb(II) from aqueous solution onto Unye (Turkey) bentonite in raw (RB), iron oxide-coated (ICB) and magnesium oxide-coated (MCB) forms. Adsorption of Pb(II) by samples was investigated as a function of the initial Pb(II) concentration, solution pH, ionic strength, temperature and inorganic ligand effect (Cl(-)). Changes in the surface and structure were characterized by means of XRD and N(2) gas adsorption data. The Langmuir monolayer adsorption capacities of RB, ICB and MCB in 0.1M KNO(3) solution were estimated as 16.70, 22.20 and 31.86 mg/g, respectively. The spontaneity of the adsorption process is established by decrease in DeltaG which varied from -21.60 to -28.60 kJ/mol (RB), -21.74 to -32.22 kJ/mol (ICB) and -26.27 to -33.11 (MCB) in temperature range 303-338 K.