Effect of sol-gel preparation on the microstructural and thermal behavior of nanosized powder of mesoporous hydroxyapatite

Abstract

The effect of sol-gel preparation on the microstructural and thermal behavior of nanosized mesoporous hydroxyapatite powder was investigated in this study. The powder was synthesized using the sol-gel technique, with preparation carried out at various temperatures: room temperature 100°C and 400°C. FTIR analysis revealed the presence of hydroxyl groups (3423.91 cm⁻¹ to 3600 cm⁻¹), corresponding to the stretching vibration of hydroxyl (OH) and phosphate ions (1102.31 cm⁻¹ to 1644.17 cm⁻¹), indicating the stretching vibration of P - O, and these indicating the functional groups of PO₄^3- , confirmed as the formation of hydroxyapatite. The thermal properties were studied using DSC-TG and provide valuable information on phase transitions such as melting, crystallization, thermal enthalpy, and specific heat capacity. XRD analysis confirmed all materials as nanosized mesoporous hydroxyapatite powder with face-centered cubic unit cells in the hexagonal lattice system. The lattice constants were obtained, a = b = 0.942 nm and c = 0.588 nm; these results were determined by careful analysis using the appropriate interplanar spacing formula. Finally, the surface topology and elemental composition were examined using SEM-EDX, including the atomic ratio of elements in the nanosized mesoporous hydroxyapatite powder. The Ca/P ratios were found to be approximately 1.63 and 1.73 for samples treated at temperatures of 100°C and 400°C, respectively. In the future, nanosized mesoporous hydroxyapatite powder, synthesized by the sol-gel method, could be prepared as a raw material for waste adsorbents.