Synthesis of Hydroxyapatite from Egg Shell Bio-Waste for Use in Functionally Graded NiTi/HA Bone Implants

Abstract

Hydroxyapatite, a bio-ceramic material widely utilized in bioengineering, holds significant promise for bone implant applications due to its biocompatibility and nontoxic nature. This study focuses on the organic synthesis of hydroxyapatite with tailored nanoscale properties suitable for integration into functionally graded materials like NiTi/HA, intended for bone implants. Porous NiTi possesses desirable mechanical properties for such applications; however, its limited bioactivity poses a challenge for therapeutic use. Composite structures comprising porous NiTi and hydroxyapatite (HA) offer a viable solution to promote bone ingrowth and implant integration with surrounding tissue. Eggshells serve as the raw material in this research, subjected to calcination at 1000℃ for three hours to yield calcium oxide. Subsequent crushing and mixing with phosphoric acid, followed by milling using a planetary ball mill for twenty-two hours at 45 rpm, produces a homogeneous hydroxyapatite powder (HA). Comprehensive characterization using particle analysis, FTIR, SEM, and XRD confirms the desired properties of the synthesized powder. FTIR analysis verifies the presence of fundamental HA components, while XRD reveals a structure akin to traditional hydroxyapatite powder, featuring characteristic peaks corresponding to (PO43−), (CO32−), and bending OH−. Particle size analysis indicates a range of (0.301) µm to (4.759) µm, with a mean size of (1.088) µm. The findings of this study highlight that hydroxyapatite powder derived from eggshells exhibits favorable particle size, bioactivity, and porous nature, rendering it well-suited for incorporation into bone implant materials.