Development of new synthesis routes for hydroxyapatite nanopowders production from chicken eggshells

Hydroxyapatite (HA) nanopowders are attracting interest for surface application to ceramic biomaterials. In this study, we developed innovative and new viable synthesis routes of calcium phosphate nanopowders from the natural calcium carbonate of chicken eggshells. Following the four routes, alternative co-precipitation, vacuum process, brushite, and calcination, we obtained the HA samples, which were then characterized by different methods. The X-ray diffraction /Rietveld method showed the HA phases, monetite and brushite crystallinity with greater symmetry, and nanoscale. Transmission electron microscopy showed the morphology of nanoparticles functionalized nanoparticles smaller than 100 nm in routes A, B and D, and Fourier-transform infrared spectrophotometry and Raman spectroscopy identified the classic chemical groups of calcium phosphates by four routes mainly groups (PO₄)^3- and (CO₃^-). Scanning electron microscopy analysis revealed a good surface topography to future cell biointeraction in A, B and D routes, and thermogravimetric analysis showed the mass loss profile inherent to each synthesis route with slot at 200 °C. Hence, the eggshell HA and brushite and the specific monetite nanoparticles with different morphology can be prepared from the four new possible and viable routes using different methods. (author)