Synthesis of hydroxyapatite from eggshell powders through ball milling and heat treatment

AbstractEvery day, several million tons of eggshells are being generated as bio-waste across the world. This study demonstrates the synthesis of HA powder using dicalcium phosphate dehydrate (CaHPO4·2H2O, DCPD) and eggshell powders via ball milling and subsequent heat treatment. The formation of HA phase can be initiated by sintering the 1h milled sample at 1000°C for 1h, while pure HA phase can be obtained upon sintering the 10h milled sample. Additionally, the final products composed of biphasic calcium phosphate (HA+β-TCP crystals) can easily be prepared by ball milling for 5h followed by heat treatment at 1000°C for 1h. The carbonate peaks observed in the FTIR analysis of the as-prepared HA closely matched those of A- and B-type carbonates, which is typical of the biological apatite. The elemental composition of the as-synthesized HA showed the presence of Ca, P, Mg, and Sr