Adsorptive removal of lead(II) ion using Natural Red Earth from its iron and aluminum oxide forms

摘要

Adsorption characteristics of Pb(II) onto Natural Red Earth (NRE), have been studied in batch technique to ascertain the effect of pH, ionic strength, initial sorbent and sorbate concentrations and time. FITEQL computer algorithm was used to optimize the intrinsic constants of sorption reactions. Solid suspension (5 g/L NRE) was sufficient to remove Pb(II) up to 8.92 mol/L. Lead(II) adsorption achieved its maximum adsorption of nearly 100% at neutral to slightly acidic conditions. The rate of adsorption of lead(II) was very fast and followed the Psuedo second order model. Lead(II) adsorption onto NRE was better explained by Langmuir-Freundlich isotherm. Negative Gibbs free energy values indicated spontaneity of Pb(II) adsorption. FITEQL optimization suggests a mixture of monodentate and bidentate surface complexes formed within Pb(II) and surface sites of NRE. These results suggested that the NRE could be effectively used as a low cost candidate for removal of Pb(II) from environmental water.