Comparative of the removal of Pb~(2+) , Cd~(2+) and Ni2 by nano crystallite hydroxyapatite from aqueous solutions: Adsorption isotherm study

摘要

Release of heavy metal onto the water and soil as a result of agricultural and industrial activities may pose a serious threat to the environment. In this study, the adsorption behavior of nano hydroxyapatite with respect to Pb~(2+), Cd~(2+) and Ni~(2+) has been studied in order to consider its application to purity metal finishing wastewater. The batch method has been employed, using metal concentrations in solution ranging from 100 to 400 mg/L. The uptake capacity and distribution coefficients (K_d) were determined for the adsorption system as a function of sprbate concentration. The Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DRR) isotherms applied for sorption studies showed that the amount of metal sorbed on nano hydroxyapatite. It was found that the adsorption phenomena depend on charge density and hydra ted ion diameter. According to the equilibrium studies, the selectivity sequence can be given as Pb~(2+) > Cd~(2+) > Ni~(2+). These results show that nano hydroxy apatite holds great potential to remove cationic heavy metal species from industrial wastewater.