Enhanced biodiesel production from waste cooking palm oil, with NaOH-loaded Calcined fish bones as the catalyst

The present work mainly focuses on the development of heterogeneous catalysts from fishbone, loaded with sodium hydroxide for transesterification of biodiesel. The catalyst was developed using a two-step process involving the calcination of fishbone at 900 °C, followed by a hydrothermal process with a sodium hydroxide-loaded (NaOH) solution. The synthesized heterogeneous catalyst was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and BET surface area analysis. The transesterification of waste cooking palm oil (WCO) with BC-NaOH shows a maximum yield of up to 98% for 2.5 wt.% catalyst loading, 1:9 oil:methanol molar ratio at a temperature of 65 °C for a reaction time of 1.5 h. The enhanced catalytic activity is due to the high base active site density of hydroxyl groups from hydroxyapatite, β- tricalcium phosphate, and sodium hydroxide. A gas chromatography-mass spectroscopy (GC-MS) was performed to determine the conversion of oil to biodiesel. The reusability of the catalyst was confirmed from the consistency in the biodiesel yield obtained in up to 7 cycles.