Research on Adsorption Capacity for Ni2+ and Mechanism of Nano-hydroxyapatite

Nano-hydroxyapatite was prepared by chemical precipitation with Ca(NO3)2 and (NH3)2HPO4 as reagent. The phase composition, crystal morphology and specific surface area were characterized by XRD,TEM and BET. The results indicate that n-HA synthesized shows needlea2like morphology with uniform average size of 31.9nm 1.3nm, week crystallinity, high surface energy, and the specific surface area of 135m2/g. Ni2+ is selected as adsorption object ion, the Langmuir adsorption isotherm is applicable when Ni2+ initial concentration is lower than 0.1mol/L, whereas when Ni2+ initial concentration is higher than 0.1mol/L, Ni2+ substitutes Ca2+ and binds with atom O on the surface. The adsorption of Ni2+ on na2HA concludes ion exchange, electrostatic adsorption and dissolution-precipitation processes, This result is proved by the change on surface potential, crystal phase composition and binding energy of surface elements of n-HA before and after adsorption, which are analyzed by Zeta potential, XRD and XPS.