DEVELOPMENT OF HYDROXYAPATITE DERIVED FROM INDIAN CORAL

A simple method of converting the calcium carbonate skeleton of the co rals available in the Indian coast into hydroxyapatite granules has be en developed. By heating the coral to 900 degrees C, the organic mater ials were eliminated. Powder X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were employed to characterize the coral and to optimize the pro cessing parameters as well as to confirm the hydroxyapatite formation. The coral used exhibits the presence of both aragonite and calcite ph ases (dimorphism). At a temperature of 900 degrees C the coral was fou nd to decompose all the carbonate phases. The pre-heated coral is conv erted into hydroxyapatite by a chemical exchange reaction with di-ammo nium phosphate under hydrothermal conditions. The hydroxyapatite obtai ned was in powder form and does not contain any impurities, The in vit ro solubility test of the apatite granules performed in Gomoris, Micha lelis, Sorensens, Ringer's and phosphate buffer of pH 7.2 and de-ioniz ed water indicated the stability of the coralline hydroxyapatite. (C) 1996 Elsevier Science Limited