Inorganic oxide nanoparticles synthesized from Aceh bovine bone through sol–gel method: effect of precipitation agents on the physicochemical properties and its cata-lytic activities in transesterification palm oil into biodiesel

This study aims to synthesize CaO based inorganic oxide nanoparticles from Aceh bovine bone for transesterification of RBDPO to biodiesel. The synthesis carried out through a sol gel method using different precipitating agents of NaOH and NH4OH, calcined at 700 °C for 4 h. The XRD diffractogram shown the cristalline phases of inorganic oxide nanoparticles resulted from the Aceh bovine bone contained three main compound phases which consisting of hydroxyapatite (Ca10(PO4)6(OH)2), calcium carbonate (CaCO3), and calcium oxide (CaO), the calcination assisted the crystallinity of inorganic particles. FTIR spectra shown the presence of OH-, CO3²⁻, and PO4³⁻ functional groups in the obtained inorganic oxides particles, while the SEM-EDS characterization revealed the obtained inorganic particles has smooth and homogeneous particle morphologies which dominated by Ca, P, and O elements. TEM analysis shown the particle size has been in nanoscale, with most particle sizes of 40 nm for NaOH precipitating agent and 27 nm for NH4OH, whereas the UV-DRS spectra showed the apparent optical band gap energies of 3.1 eV and 3.2 eV, respectively. The synthesized inorganic oxides nanoparticle successful applied for catalizing the transesterification of RPDPO oil into methyl esters, which cointaining methyl palmitate and methyl oleate as predominantly compound.