Application of full factorial design and Doehlert matrix for the optimisation of beef tallow methanolysis via homogeneous catalysis

The transesterification of triglycerides by means of alkaline catalysts is the most widely used route for biodiesel production and reaction optimisation by multivariate methods has been used for biodiesel production from different vegetable oils. However, the application of simultaneous optimisation for biodiesel production from beef tallow has received little attention. In an effort to optimize the beef tallow biodiesel production, a combination of the full factorial design and the Doehlert matrix was applied, and the effects of temperature, reaction time, catalyst concentration and alcohol:tallow molar ratio and their reciprocal interactions were assessed. The response variables under study were purity and yield of the final biodiesel product. In the selected condition [alcohol:tallow molar ratio (M) = 7.5:1, catalyst:tallow mass ratio (C) = 1.5%, reaction time (t) = 20 min and temperature = 50 °C], the conversion yield of tallow biodiesel was 88.4% and the purity was 99.4%. The final biodiesel obtained was analysed and showed to have good quality characteristics.