Taguchi grey relational optimization of sol–gel derived hydroxyapatite from a novel mix of two natural biowastes for biomedical applications

The comparative study of natural hydroxyapatite (NHAp) from bovine (B) and catfish (C) bones using different fabrication parameters has been extensively researched through traditional investigation. However, the quantitative effect optimization of a novel mix proportion of hydroxyapatite from these bones, and fabrication parameters have not been examined. Hence, this study presents the effect of the powder mixture, compaction pressure, and sintering temperature (as production parameters) on the experimental mechanical properties of naturally derived HAp. The bovine bone and catfish bone biowastes were used in mixed proportions to produce hydroxyapatite via the sol–gel synthesis protocol. The powders were calcined separately at 900 °C to convert the deproteinized biowaste. Next, the powders were combined chemically (sol–gel) in the appropriate ratios (i.e. 45 g of B: 15 g of C (B75/C25), 30 g of B: 30 g of C (B50/C50), and 15 g of B; 45 g of C (B25/C75)). Taguchi design supported by grey relational analysis was employed with an L9 orthogonal array. The Minitab 16 software was employed to analyze the Taguchi design. The result revealed an inconsistency in the powder mixture as the optimum state for individual mechanical properties, but the grey relational analysis (GRA) showed better mechanical properties with a powder mix of B50/C50, 500 Pa compaction pressure, and 900 °C sintering temperature. The obtained result further showed that the novel mix of these powders is a good and promising material for high-strength biomedical applications, having a contribution of 97.79% on hardness and 94.39% on compressive strength of HAp. The obtained experimental grey relational grade of 0.7958 is within the 95% confidence interval, according to confirmation analysis (CA). The optimum powder parameter was examined using X-ray diffraction (XRD), and its structure, size, and elemental makeup were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. The sample had a higher degree of crystallinity and mean crystallite size of 80.42% and 27.3 nm, respectively. The SEM images showed big, gritty grains that are not tightly packed.