A comparative study of Cu(П) and Pb(П) adsorption by Iranian bentonite (Birjand area) in aqueous solutions

Heavy metals such as Cu(II) and Pb(II) are among the hazardous pollutants that lead to severe ecological problems and have a toxic effect on living organisms. The removal of Cu(II) and Pb(II) by Iranian bentonite experiment were conducted in single component and multi component systems. The bentonite from the Birjand area was characterized by X-ray diffraction pattern and FTIR spectroscopy. The effects of initial Cu(П) and Pb(П) concentration were investigated on the adsorption process. An equilibrium study was performed and followed by five different isotherm models which included two parameter (Langmuir, Frendlich, Temkin and D-R) and three parameter (Khan) models . From the Langmuir isotherm, the equilibrium adsorption capacity for Cu(П) is 21.10 to 22.17 mg/g in single component and multi component systems respectively, and for Pb(П) is 27.80 to 40.49 mg/g in single component and multi component systems respectively. Comparative adsorption of Cu(II) and Pb(II) onto bentonite showed that the affinity for Pb(II) to interact with bentonite is higher than Cu(II). Based on the free energy of adsorption value for Cu(П) and Pb(П), the interaction between these ions and Iranian bentonite is chemical adsorption, that is to say, ion exchange.