Removal of nickel (II) from aqueous solutions by using nano-crystalline calcium hydroxyapatite

The potential of the synthesized nano-hydroxyapatite to remove Ni2+ from aqueous solutions was investigated in batch reactor under different experimental conditions. The study also investigates the effects of process parameters such as initial concentration of Ni2+ ion, temperature, and adsorbent mass. Various thermodynamic parameters, such as Delta G degrees, Delta H degrees and Delta S degrees have been calculated. The thermodynamics of Ni2+ ion onto nano-HAp system indicates spontaneous and endothermic nature of the process. Nickel uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich model. The adsorption data follow the adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 46.17 mg/g of Ni2+ ions on nano-HAp. (C) 2010 King Saud University. Production and hosting by Elsevier B.V. All rights reserved.