Biodiesel production from used vegetable oil and CaO catalyst impregnated with KNO3 and NaNO3

The rise in global energy demand has encouraged exploring into other innovative methods of generating renewable fuels from different forms of waste. Due to its accessibility, culinary used vegetable oil is regarded as a potential source for profitable production of biodiesel. In the present study, the viability of producing biodiesel from used vegetable oil (UVO) by utilizing CaO catalyst (derived from the calcination of chicken eggshell and impregnated with KNO3 and NaNO3) was studied. Higher yield of biodiesel was obtained at methanol/oil mole ratio of (9–10) and CaO catalyst concentration of (2.0–3.0) wt/wt% Oil, for the three forms of catalyst used. Also, higher yield of biodiesel was obtained when CaO with impregnated KNO3 was used, followed by the operation involving CaO with impregnated NaNO3. At optimum conditions of methanol/oil mole ratio of 9 and catalyst concentration of 2.4 wt/wt% Oil, the yields of biodiesel obtained were 90% (for unimpregnated catalyst), 92% (using CaO impregnated with NaNO3) and 95% (using CaO impregnated with KNO3). The higher biodiesel yield obtained for CaO impregnated with KNO3 (compared to the yield from CaO impregnated with NaNO3) could be traced to a more reactive nature of potassium and arrangement of electrons of both potassium and sodium. The results of the tests and analysis on biodiesel properties reveal that quality biodiesel were produced from the three forms of catalyst used. This is because, each of the values of the properties considered falls within the ASTM standard.