Development carbonated hydroxyapatite powders from oyster shells (Crassostrea gigas) by carbonate content variations

Carbonated hydroxyapatite (CHAp) is an inorganic mineral that more closely resembles the main component of composing human hard tissue in 2-8 wt carbonate content. CHAp powders have been synthesized from oyster shells using the precipitation method. Oyster shells are one type of shellfish from the bivalve class which is rich in calcium carbonate content. In this research, CaO from oyster shells obtained from the decomposition process of CaCO3 was used as a source of calcium and diammonium hydrogen phosphate and ammonium bicarbonate as well as a precursor of phosphate and carbonate, respectively. In addition, carbonate content variations were x = 0, 0.3, 0.8 and 1.2 which were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), and scanning electron microscope-energy dispersive X-Ray (SEM-EDX) to determine the functional groups, crystallographic properties, morphology and Ca/P molar ratio, respectively. Carbonate ion substitution in the hydroxyapatite crystal structure is known to decrease crystallinity and crystallite size. The theory is in accordance with the results obtained in this study with the crystallite size is 74.322, 46.933, 37.727, and 31.499 nm for 0.95, 2.7, 5.7, and 9.35 wt. carbonate content, respectively. © 2020 Trans Tech Publications Ltd, Switzerland.