Valorizing waste palm oil towards biodiesel production using calcareous eggshell based heterogeneous catalyst

This study aimed at transesterifying waste palm oil (WPO) into biodiesel employing metal oxides impregnated calcareous catalyst from discarded eggshells. Catalyst concentration, methanol to oil molar ratio, reaction time and temperature were optimized for biodiesel synthesis adopting the L16 Taguchi orthogonal array. One output response (biodiesel yield%) was measured for each trial. The signal-to-noise (S/N) ratio and analysis of mean (ANOM) were also used to find the ideal input parameter towards best output response. The analysis of variance (ANOVA) was additionally used to analyze the input factors on the response. Optimized conditions achieved were: catalyst concentration-7 wt%, methanol:oil-12:1, reaction time-180 min and reaction temperature-150 °C. Variation in catalyst concentration was observed as most significant factor on the biodiesel yield (∼94.5 %). Catalyst was reused for 6 cycles following the same experimental conditions and yield on 6th cycle is 70 %. Confirmation tests were used to validate the optimization result of the current study.