Synthesis of hydroxyapatite using phosphate-rich glasses in the system CaO-P2O5-H2O and acoustic waves
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Phosphate-rich glass powders in the CaO-P2O5 system were prepared by the sol-gel method using aqueous solutions of Ca(NO3)2·4H2O and H3PO4. Glass powders were subjected to reaction with Ca(OH)2 and water under varied experimental conditions, such as temperature (25–90 °C), particle size (1–5 and 40 μm), and ultrasound waves (20 kHz). Parallel experiments were also conducted without ultrasound for comparison. The reaction products were composed of Ca(H2PO4)2·H2O (monocalcium phosphate monohydrate), CaHPO4 (monatite), CaHPO4 · 2H2O (brushite), Ca5(PO4)3OH (hydroxyapatite) and amorphous calcium phosphate. It is interesting to note that hydroxyapatite and brushite were obtained at a low temperature of 60 °C in a very short period of time (30 min). All samples were characterized by X-ray diffraction and scanning electron microscopy.
KeywordsScanning Electron Microscopy 2H2O Hydroxyapatite Acoustic Wave H3PO4
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