Bio-based hydroxyapatite nanoparticles were synthesised via the sonochemical route using phosphoric acid and bio-based calcium carbonate particles extracted from eggshells. Hydroxyapatite is a natural bio ceramic material that contains calcium phosphate group. In this procedure phosphoric acid solution was used as the source of phosphorus and eggshell particles were used as the source of calcium. Eggshells represent a great renewable material for structural applications due to the high content of inorganic calcite. Eggshells were cleaned and ball milled to reduce their sizes to nanoscale. The particles were then heated in a tube furnace to produce calcium oxide particles; these calcium oxide particles were stirred in water for 24 hours at room temperature and formed calcium hydroxide. Phosphoric acid and calcium hydroxide particles were irradiated with high intensity ultrasonic horn for two hours at 10°C in the presence of distilled water. The resultant product was characterised using XRD, TEM and surface area measurements. These results showed that the as-prepared hydroxyapatiteparticles are porous (~20–50 nm), crystalline in nature and thermally stable at least up to 750°C. BET studies showed that as-prepared hydroxyapatite nanoparticles have a surface area of 58.8 m
/g. These nanoparticles can be used in bio medical applications and in the field of nanocomposite structures.
Keywords: hydroxyapatite, bio nanoparticles, eggshell and sonochemical method