Abstract

The potential of the synthesized nano hydroxyapatite to remove Pb (II) 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 Pb (II) ion, temperature and adsorbent mass. Various thermodynamic parameters, such as G°, H° and S° have been calculated. The thermodynamics of Pb (II) ion onto nano HAp system indicates spontaneous and endothermic nature of the process. Lead uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) model. The adsorption data follow the Langmuir model better than the Freundlich and DKR model and the adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 714.286 mg/g of Pb (II) ions on nano HAp. 

Key word: Adsorption, nano crystalline hydroxyapatite, Pb (II), thermodynamic parameters, adsorption isotherms.