and Cd were calculated by lead nitrate and cadmium nitrate. The homogenous mixed lead nitrate and
cadmium nitrate amount with 1.3 kg soils was loaded in plastic pot (15cm diameter,18cm height), and
was then equilibrated for two month with frequent thorough mixing at room temperature.
Nano-hydroxyapatite (nHA) used in this study (purity 99.9%) was purchased from DK nano-material
company (Beijing, China).The chemical composition and the specific surface area of the nHA were in
Table. 2. The crystalline structure and particle size of nHA were determined with X-ray Diffraction
(Rigaku, Ultima IV, Japan) and Scan Electron Microscopy (SEM, JSM-6510LV), respectively.The
average particle size of nHA was 20 nm. TEM results illustrated that the nHA material was nano-rod
structure, with dimensions of 40 nm (wide)h200 nm (length). The Ca/P molar ratio of nHA was 1.67
using XRF methods. The specific surface area of nHA was calculated as 50 m2
g-1 by the BET method.