Preparation and Microstructural Characterization of Natural Hydroxyapatite Extracted from Animal Bones

An attempt has been made to optimize the heating treatment temperature of a fresh bovine bone sample using thermogravimetric and differential thermal analysis (TGA/DTA) between room temperature and 1000 degrees C in atmospheric air. It has been shown that the organic matter and carbonate have been totally removed from the washed bone powder after calcining at 800 degrees C. To investigate the effect of the residence time of the thermal treatment at 800 degrees C on the crystallinity and the morphology of the hydroxyapatite (HA) samples, FTIR-ATR produced crystalline indices (CIs) calculated for 1 h, 6 h, 12 h, 24 h and 48 h as holding times are compared to those obtained through XRD. Scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analyses were also performed. The CI result shows that, quantitatively speaking, the values obtained by these two techniques were not comparable although the general trends were similar. From SEM pictures and the corresponding EDX results, the samples subjected to calcination at 800 degrees C had relatively the same sized spherical morphology and the same Ca/P ratios close to the standard one (approximate to 1.67) regardless of the preparative calcining time.