Research on Adsorption Capacity for Ni~(2+) 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 needle-like morphology with uniform average size of 31.9nm×21.3nm,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 n-HA 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.