Biodiesel production from low-grade cooking oil using calcium oxide based catalyst: preparation and characterization

Abstract

One of remarkable alternative fuel is biodiesel to widely used petroleum-derived since it can be generated by domestic natural resources such as palm oil and vegetable oils. Palm oil, in the form of low-grade cooking oil has been used for the biodiesel oil production. In this study, the calcium oxide-based catalyst supported on alumina using wetness impregnation method was synthesized. The transesterification of low-grade cooking oil into biodiesel was carried out for 2 hours, temperature at 60-65°C with methanol to oil ratio 18:1. The American Society for Testing and Materials (ASTM) method were used in characterization of biodiesel to evaluate the fatty acids, acid value, saponification value, cloud point and pour point of biodiesel. The presence of functional groups in cooking oil and biodiesel were observed using FTIR analysis. The peak at 3325.63 cm-1 shows the OH- bonding existed in biodiesel oil. Meanwhile, a strong absorption of the carbonyl (C=O) groups that corresponding to ester present in the low-grade cooking oil and biodiesel at 1743.72 cm-1 and 1743.94 cm-1 respectively. The characteristic value of low-grade cooking oil and biodiesel obtained were under permissible limit standard with free fatty acids of 0.7-1.5%, acid value 1-2.33% and saponification value of 164-218 mgKOH/g. Based on the analyze results, it shows that low-grade cooking oil and biodiesel are suitable to be used as alternative for non-fossil fuels.