Valorization of emperor fish (Lethrinus fraenatus) filleting waste in to fishbone hydroxyapatite by thermal calcination method

The experiment was carried out to extract hydroxyapatite from emperor fish (Lethrinus fraenatus) bones collected as waste during fish filleting. Thermal calcination at 900 °C for 5 h was used to carry out the extraction. Several techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and in vitro cytotoxicity assay were employed to characterize the derived hydroxyapatite. TGA showed excellent thermal stability. A microstructure picture of the amorphous hydroxyapatite particles with crystal agglomerates was provided by SEM. EDX spectroscopy revealed that the extracted hydroxyapatite had a Ca/P weight ratio of approximately 1.67, indicating that its composition was compatible with HA. The XRD pattern disclosed the crystallinity and purity of nano-sized hydroxyapatite particles found in correlation with the ICSD (Inorganic Crystal Structure Database) collection Code: 261063/2010. The presence of distinct hydroxyl peaks at 630 cm⁻¹ and phosphate peaks at 550–1200 cm⁻¹ was confirmed by FT-IR. The MTT assay confirmed that the extracted Hydroxyapatite was not cytotoxic. These results highlight the potential of fish filleting waste to be valorized into HyAp as a biomaterial for the manufacturing of bone tissue.