Synthesis and characterization of sol–gel derived hydroxyapatite from a novel mix of two natural biowastes and their potentials for biomedical applications

The surge in meat and fish processing in Nigeria has resulted in a significant increase in biowaste production and these wastes can be salvaged, allowing for the extraction of calcium phosphates and a reduction in solid waste in the concerned industries. These biowastes, particularly animal bones and fish bones can be used as the precursors for the synthesis of hydroxyapatite (HAp), a very popular member of the family of calcium phosphates. In this present study, for the first time, we report the utilization of animal bone biowaste and catfish bone biowaste in mixed proportions to produce hydroxyapatite by using the sol–gel synthesis protocol. The conversion of the as-received deproteinized biowastes was conducted by calcining the powders independently at 900 °C, followed by a chemical mixing process (sol–gel) of the mixed powders in specified proportions (C100_, BC 75/25_, BC 50/50, BC 25/75, and B 100: C-catfish bones and B: animal bones). X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the samples, while scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis were used to investigate the structure, size, and elemental composition of the derived mixed and stand-alone powders. The sample BC 50/50 exhibited a higher degree of crystallinity and a mean crystallite size of 80.42% and 27.3 nm, respectively. EDS analysis showed that the atomic Ca/P ratios of the as-synthesized HAp samples ranged from 2.379, to 3.10. The obtained products are Mg containing except for the BC 75/25 with B 100 having a higher Mg wt% of 1.538 and lowest reactivity potential by reason of its lowest crystallite size. Thus, sample B100 can be of higher potential for biomedical applications.