Optimization of biodiesel produced from waste sunflower cooking oil over bi-functional catalyst

Abstract

In the current global climate emergency and with the interesting environmental advantages of biodiesel, a look into the commercialisation of such greener fuel is essential. While raw materials account for the most in the production cost, time and energy can be economised using statistical models. The optimisation of free methyl esters (FAME) synthesised from waste sunflower oil over a novel CaO/Al2O3, and methanol was carried out at the alcohol and oil ratio of 12:1. The aim was to investigate the effect of operation parameters on the yield of the produced sunflower biodiesel, with the use of low cost and time efficient central composite response surface methodology. The chosen variables were catalyst loading, temperature, and time while the response was the yield. The catalyst loading was the most consequential parameter on yield. The linear regression model was obtained to predict responses given by these variables, with 95% confidence. The predicted and experimental yield was comparable with 92.773% and 95.665% respectively. A significant yield of 98.23% was obtained at optimal operating conditions of catalyst loading (2.5 wt%), time (5 h) and temperature (60 ◦C). The properties of optimised FAME were within international standard limits set for biodiesel except for the high concentrations of Ca and Mg.