Desalination, vol.279, no.1-3, pp.75-85, 2011 (SCI-Expanded)
This paper presents the synthesis, structural characterization and Pb(II) adsorption behavior of K-birnessite and H-birnessite samples. Changes in the surfaces and structure of birnessite samples were characterized by means of infrared spectroscopy (IR), N2 gas adsorption and thermal analysis (TG-DTA) techniques. 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 (NO3-, Cl-). The Langmuir monolayer adsorption capacities of K-birnessite and H-birnessite samples in 0.1M NaNO3 solution at 298K were estimated as 164.30 and 133.17mg/g, respectively. Thermodynamic parameters such as change in free energy (δG), enthalpy (δH) and entropy (δS) were evaluated for K-birnessite and H-birnessite to be -22.43kJ/mol (at 298K), 23.90kJ/mol, 155J/molK, and -18.50kJ/mol (at 298K), 10.57kJ/mol, 98J/molK, respectively. © 2011 Elsevier B.V.