Mineralogical transformation during hydroxyapatite dissolution in simple aqueous solutions

In this study we investigated the early stage of HAP dissolution at 25°, 50° and 70 °C using solubility and ATR-FTIR spectroscopy measurements. We found a non-stoichiometric release of calcium and total phosphorus in solution in the experimental close to neutral pH conditions. The ATR-FTIR measurements revealed the presence of new peaks corresponding to the vibrations of HPO42 − group. Comparing HAP spectra of the pristine surface to those obtained after 7 days of hydration we propose the presence of monetite (CaHPO4). This rapidly formed new phase would affect the observed low solubility of HAP and its presence could validate the use of this mineral in paleo-environmental reconstructions and ecological remediation strategies.