Removal of lead ions by acid activated and manganese oxide-coated bentonite

This paper presents the adsorption of Pb(II) from aqua solutions onto Unye (Turkey) bentonite in raw (RB), acid activated (AAB) and manganese oxide-coated (MCB) forms. Adsorption of Pb(II) by RB, AAB and MCB sample was investigated as a function of the initial Pb(II) concentration, solution pH, ionic strength, temperature and inorganic ligand (Cl−). Changes in the surfaces and structure were characterized by means of XRD, IR and potentiometric titration. The Langmuir monolayer adsorption capacities of RB, AAB and MCB in 0.1 M KNO3 solution were estimated as 16.70, 8.92 and 58.88 mg/g, respectively. The spontaneity of the adsorption process is established by decrease in ΔG which varied from −21.60 to −28.60 kJ/mol (RB), −22.63 to −29.98 kJ/mol (AAB) and −19.57 to −26.22 (MCB) in temperature range 303-338 K.