Acidic dissolution mechanism of natural fluorapatite .2. Nanolevel of investigations

Dissolution process of natural fluorapatite in phosphoric acid at the nanolevel was investigated by scanning electron microscopy, Auger-electron and infrared spectroscopy. Dissolution process at this level was described by nonstoichiometry of the ionic dissolution from the crystal lattice of fluorapatite. The experimental data obtained were extended with the results taken from literature. The following sequence of ionic dissolution was proposed: first fluorine, next calcium and afterwards phosphate. A new mechanism for apatite dissolution at the nanolevel was created as a result. This mechanism was based on the chemical logic and consisted of five chemical reactions, following one after another. A schematic description of this mechanism is also presented.