Synthesis and characterization of carbonated calcium and lead apatites

CHED 1237

Mitchell P. Sternlieb, msternli@fandm.edu, Department of Chemistry, Franklin and Marshall College, Lancaster, PA 17604 and Claude H. Yoder, claude.yoder@fandm.edu, Department of Chemistry, Franklin & Marshall College, P.O. Box 3003, Lancaster, PA 17604-3003.
Apatites, a diverse family of minerals, are found in the environment and in bones and teeth. They have the stoichiometry M10(PO4)6Z2, where M is a divalent cation and Z is a halide, hydroxide, or carbonate. The complexity of the apatite structure renders it vulnerable to ionic substitutions, which significantly alter physical and chemical properties. Calcium and lead apatites of various carbonate contents were prepared in aqueous media and identified by X-ray diffraction. Carbonate percentages were determined by combustion analysis. Solubility and M and P percentages were determined with ICP-AES. The lattice parameters were determined using X-ray diffraction and the atomic order was determined with microprobe Raman Spectroscopy. Ion products were calculated with Visual MINTEQ equilibrium software. Thermodynamic calculations predict that the solubilities of calcium and lead apatites increase with increasing carbonate incorporation.