Utilization of a cost effective solid catalyst derived from natural white bivalve clam shell for transesterification of waste frying oil

The solid oxide CaO catalyst derived from natural white bivalve clam shells were employed to produce biodiesel via transesterification of waste frying oil (WFO). The shell materials were calcined in a muffle furnace at 900 °C with an optimum time of 4 h to transform calcium species in the shells into active CaO catalyst. The catalyst was characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive Atomic X-ray Spectrometry (EDAX). The activity of the natural CaO catalyst was compared with the commercial CaO. A high biodiesel yield of 95.84% was obtained at a methanol/oil molar ratio of 18:1, 8.0 wt.% catalyst, 3 h reaction time and temperature of 65 °C. The biodiesel composition was determined by Gas Chromatography coupled with Mass Spectroscopy (GC–MS).