Pyrolytic synthesis of hydroxyapatite from bovine bone: A response surface methodology approach

Hydroxyapatite (HA) was synthesized from bovine bone by pyrolysis, and the calcination process was optimized using response surface methodology (RSM) with a central composite design (CCD). The effects of temperature (500-1000?C) and residence time (1-5 h) on crystallinity were evaluated through eleven experiments. The quadratic model showed excellent agreement with experimental data (F = 683.31, p < 0.0001 ; R? = 0.9985, predicted R? = 0.9852). Optimum conditions (793.5?C, 4.3 h) yielded HA with 98.86% crystallinity, which closely matches the predicted value of 98.03%. X-ray diffraction confirmed phase-pure HA with lattice parameters a = 9.44 ?, c = 6.91 ?, ? = 533.3 ?? and an average crystallite size of 42.46 nm. FTIR spectra showed phosphate and hydroxyl bands, while SEM and TEM revealed porous agglomerates of nanosized particles (20-60 nm). This approach provides a sustainable and economically viable method for synthesizing HA for use in biomedicine.