Synthesis of Hydroxyapatite from Precipitated Calcium Carbonate of Thorny Shells (Murex trapa) with Variable Ca/P Mole Ratio and pH

Abstract

Hydroxyapatite, with the chemical formula Ca₁₀(PO₄)₆(OH)₂, is a mineral found in human bones and teeth, providing density and strength to bones as it is a major component of the bone matrix. It is widely used in biomedicine for bone implants, dental fillings, and hard tissue replacement. Hydroxyapatite can be produced from materials high in CaCO₃, such as cattle bones, seashells, and fish bones. In this research, thorny clam shells (Murex trapa), with a CaCO₃ content of 91.08%, were used. Precipitated Calcium Carbonate (PCC) was formed using the carbonation method, while hydroxyapatite synthesis was performed using the precipitation method. Variables during synthesis included Ca/P molar ratios of 1.47, 1.67, and 1.87, and pH levels of 7, 9, and 11. The best result was achieved at a Ca/P molar ratio of 1.67 and pH 9, with a yield of 96%. The hydroxyapatite was analyzed using Fourier Transform Infra-Red, revealing the core groups PO₄^3-, CO₃^2-, and OH^-.Scanning Electron Microscopy-Energy Dispersive X-Ray analysis showed the hydroxyapatite had a crystalline structure, tending to be spherical and agglomerated.