Physico-chemical investigations of hydroxyapatite converted from phosphate rocks of M'dhilla deposit

Calcium hydroxyapatite-aspartate cahap-(asp) and calcium hydroxyapatite-glutamate cahap-(glu) hybrid materials were prepared by the dissolution of tunisian phosphate rocks in concentrated nitric acid and re-precipitation in basic solution in the presence of aspartic and glutamic acids. chemical analyses,x-ray powder diffraction,infrared spectroscopy,13c mas-nmr spectroscopy,thermogravimetry and scanning electron microscopy were used to characterize the materials and also the organic-inorganic interfaces. all techniques converge to the formation of hybrid organic-inorganic compounds composed of hydroxyapatite solids with organic anions grafted at the surface. xrd and sem observations showed that not only was the crystallinity significantly affected by the presence of organic anions,but also the structural and morphological properties. the presence of grafted organic anions has been confirmed by ir and 13c ms-nmr spectroscopies,and their amount has been evaluated by tg and chemical analyses.