This study optimized the conversion of animal fat wastes into ethylic biodiesel by alkali-catalyzed process
under mild conditions. A mix of chicken and swine fat residues was used as feedstock for biodiesel production.
A full 33 factorial design was used to optimize process parameters for maximum fatty acid ethyl
esters yield. Factors were evaluated at three different levels: temperature (30;50;70 C), ethanol:fat molar
ratio (6:1;7:1; 8:1) and catalyst concentration (0.44; 0.88;1.32 wt.%). Effects of the process variables were
analyzed using response surface methodology. Moreover, optimum conditions were applied in a benchscale
reactor and biofuel produced was characterized. It was observed that at high temperatures (50
and 70 C), phase separation between biodiesel and glycerol was impaired. Although high conversion
was achieved (96.2%) at 70 C, this condition is not recommended because no spontaneous phase separation
was verified. On the other hand, 30 C was identified as the best temperature for biodiesel ethanolysis,
using 0.96 wt.% catalyst and 7:1 ethanol:fat molar ratio. With these conditions, it is possible to achieve
around 83% conversion. Despite the oxidative stability and total glycerin, biodiesel measured properties
agreed with quality requirements established by Official Regulations