Study On The Preparation Of Nano Hydroxyapatite By Hydrothermal Method

As a kind of bioactive material, hydroxyapatite (Ca(PO)(OH) ) is noncarcinogensis, nonsideeffect and biocompatibility, so the preparation of hydroxyapatite with various appearances and structures has got much attention in recent years. In this paper, Hydroxyapatite (HA) nanoparticles were prepared by direct hydrothermal method, hydrothermal microemulsion method, and hydrothermal recrystallization method, the purpose of this work is to carry on previous technical process research and theory analysis for its application. Techniques of XRD, FTIR, EDS, FE-SEM, TEM and BET were used to characterize the composition, structure and morphology of the synthesized particles. The effects of process parameters on the nanoparticles have been studied.Firstly, HA nanoparticles were synthesized via a direct hydrothermal method. Different conditions, such as the species and use level of addition agent, reaction time, were investigated in order to ascertain their influence on the compositions and structures of HA nanoparticles. The experimental results showed that the obtained products were HA nanorods, when the addition agent was TX-100, and reaction time was 130℃.Secondly, HA hollow spheres were successfully synthesized via a hydrothermal microemulsion method. The experimental results showed that the HA hollow spheres had a diameter of 600-850nm, a wall thickness about 120nm and with a BET surface area of 65m/g. The experimental parameter of reaction time was investigated to explore the formation mechanism of HA hollow spheres. The interaction of the surfactant molecules and the inside-out Ostwald recrystallization process leaded to the formation of HA hollow spheres.Finally, HA nanorods were prepared by hydrothermal recrystallization method using Ca(NO) and (NH)HPO as reagents. Different conditions, such as pH value, crystallization time, were investigated in order to ascertain their influence on the compositions and structures of hydroxyapatite nanorods. The experimental results showed that redispersed the nanoparticles, which were separated by centrifugation from the suspension made at pH 7．5, in the clear solution, which was filtered from the colloid synthesized at pH 10．5, then heated the mixture to 180℃and recrystallized for 10h, finally, the HA nanorods with the aspect ratio value of 28 could be obtained. With different pH values of clear solution, as monomer concentration (chemical potential) changed, the aspect ratio of HA nanorods were different; when crystallization time elongated, the aspect ratio of HA nanorods was increased first, then decreased.HA nanorods and hollow spheres were prepared by direct hydrothermal method, hydrothermal microemulsion method, and hydrothermal recrystallization method. Reaction mechanics were discussed for application.