Synthesized heterogeneous nano-catalyst from cow teeth for fatty acid methyl esters production through transesterification of waste vegetable frying oil and methanol: Characterization and optimization studies

Using readily available biomass, it is possible to produce fatty acid methyl esters (FAME) at a low cost. This study focused on the transesterification process of waste frying vegetable oil to generate FAME (biodiesel) using a cost-effective heterogeneous nano-catalyst synthesized from waste cow teeth (CT). The cow teeth nano-catalyst (CTNC) was synthesized via a three-step method of calcination, hydration-dehydration, and re-calcination. The synthesized CTNC samples were characterized. The Box–Behnken design of response surface methodology (RSM) was used to obtain the optimal operating conditions that maximize the FAME yield (Y ₁) and the effects of the transesterification process conditions on FAME production. The results revealed that CTNC is of microporous structure with higher crystallinity. It consists of hydroxyapatite, beta-tricalcium phosphate, and calcium oxide, having a mean particle size of 43.96 nm, a specific surface area of 124.77 m ² /g, and a pore volume of 0.303 cm ³ /g. The process conditions that significantly influenced the EWFVOME yield were the CTNC loading, reaction time, and MTOR. A maximum of 98.70% (Y ₁) was obtained at the optimum transesterification process variables of reaction time (2 h), MTOR (12:1), and CTNC loading (3.75 wt%). The biodiesel fuel properties were found to be within the acceptable values of ASTM D6751 and EN 14214 fuel standards.