Densification of Calcium Phosphate from Biogenic Waste for Biomedical Application

Abstract

Introduction: Calcium phosphate-based biomaterial is commonly employed in biomedical applications such as dental applications, bone substitution and filler tissue engineering. Its excellent biocompatibility and potential bio-implant material have attracted many researchers to broaden their hydroxyapatite (HA) studies. Methods: The present work used waste eggshells as the source of calcium precursor to synthesize HA via a solid-state reaction. The eggshells were calcined at 700°C and mixed with the phosphate precursor, dicalcium phosphate dihydrate (DCPD). Following this, the mixture was ball-milled at 400 rpm for 2h and then heat treated at 800°C to produce pure eggshell-derived HA powder. The synthesized HA powder was then consolidated by uniaxial pressing (~6.5 – 7.1 tons) and sintered at 4 different temperatures of 1100°C, 1150°C, 1200°C and 1250°C. Results: From the XRD analysis of the sintered HA samples, it was found that an increase in sintering temperature up to 1250°C did not affect the phase stability of the HA phase. Besides that, grain size, relative density and hardness of the sintered HA samples were also increased with sintering temperature. It was observed that HA dense sample prepared by compacting at 7.1 tons followed by sintering at 1250°C showed the best combination of mechanical properties among all samples with a relative density of 94.6% and a hardness of 3.7 GPa. Conclusion: The current result is significant in supporting the potential of the synthesized eggshell-derived calcium phosphate powder as an ideal alternative for the creation of cost-effective, biocompatible biomaterials for biomedical applications.