Modified Ginstling-Brounshtein model for wet precipitation synthesis of hydroxyapatite: analytical and experimental study.

Abstract

Hydroxyapatite is the main mineral component in bones and teeth, thus being an important material in bone tissue engineering, e.g., for replacement and elimination of defects. Hydroxyapatite is widely used in real-life applications due to excellent biocompatibility and bioactivity. Wet precipitation synthesis of hydroxyapatite is limited by diffusivity. Hence, choice of a diffusion model becomes critical. The purpose of this work is three-fold. It experimentally validates the use of Ginstling-Brounshtein model for hydroxyapatite synthesis. It determines the effect of Ca(OH)2 concentration on the kinetics and reports a modified model to account for this phenomenon. It reports obtained kinetic constants that describe hydroxyapatite synthesis. Particle size was determined using scanning electron microscopy and digital microscopy. Conversion kinetics were monitored using powder X-ray diffraction. Experimental validation was provided. Furthermore, the process was found dependent on the calcium hydroxide concentration and the model was modified to account for this phenomenon. Kinetic constants describing the synthesis of hydroxyapatite were obtained and reported. The model was well consistent with the experimental data and can be used for describing synthesis of hydroxyapatite for various suspension concentrations.