Preparation and Characterization of Nano Hydroxyapatite and Its Adsorption Behavior Toward Lead Ions

Nano-hydroxyapatite with hexagonal structure was synthesized by using Ca(NO3)(2)center dot 4H(2)O and (NH4)(2)HPO4 as starting materials by chemical precipitation method assisted with different ultrasonic instruments and was used as adsorbent for removal of Pb2+ from aqueous solution. The obtained HAP was characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier infrared spectroscopy (FTIR), compared with sample S1, S2 prepared by groove ultrasonic was composed of sharp peaks, demonstrating S2 has good crystallinity. Batch adsorption experiments were employed to study the influence of parameters including reaction time, the initial concentration of Pb2+, absorbent dosage, temperature and stirring, the optimal adsorption capacity of HAP (20-30 nm) toward Pb2+ is 1269.01 mg.g(-1) when the dosage of HAP is 0.050 g and stirred at 20 degrees C for 60 min. The pseudo-first-order and pseudo-second-order kinetic models were applied to study the adsorption behavior, it was found that kinetics data followed pseudo-second-order model and Langmuir model was fitted well to describe adsorption. Desorption results indicated that the amount of desorbed from HA-Pb2+ was negligible, therefore, HAP nano powders synthesized by groove ultrasonic can be used as an efficient adsorbent with high affinity for Pb2+.