Utilization of waste banana peels as heterogeneous catalysts in room-temperature biodiesel production using a homogenizer

Banana peels as agro-waste residues contain potassium oxide as the main component after calcination. The calcined waste banana peels (WBPs) successfully transesterified palm oil to biodiesel at room temperature using a homogenizer. The catalyst was characterized by TGA, SEM, XRD and XRF. The catalytic activity of calcined WBPs was determined using parameters of the molar ratio of palm oil to methanol, catalyst weight, reaction time and rotational speed of the homogenizer. The highest biodiesel conversion of 97.7 +/- 0.6% was achieved with a molar ratio of 1 : 15, catalyst weight of 7 wt%, reaction time of 30 min and rotational speed of 6000 rpm. Unfortunately, the calcined WBP cannot be reused unless some fresh catalyst is added to defend its catalytic activity, as the concentration of K2O decreases after the reaction. However, the catalyst showed better performance as the transesterification reaction could be carried out at room temperature in a short reaction time using a homogenizer compared with other methods.