STUDY OF BIODIESEL PRODUCTION FROM WASTE COOKING OIL APPLYING THE SURFACE RESPONSE

Two ways of synthesis to produce biodiesel from waste cooking oil were compared: 1) Transesterification of fatty acids with basic catalyst (KOH) and 2) Esterification with H2SO4 followed by the transesterification evaluated previously, using factorial designs 23 with central points and the Surface Response Methodology (RSM). Raw material was characterized through its acid value and moisture content. In synthesis (1) the factorial design factors were: reaction temperature, catalyst wt%/ weight of processed oil and, methanol:oil molar ratio, and response variables were: yield of reaction, density and, kinematic viscosity, with 75 minutes as reaction time. Yields around 88% were achieved. In synthesis (2) the factorial design was applied only for esterification reaction, using two of the preceding factors and reaction time instead of temperature (fixed at 60ºC). The best conditions determined for synthesis (1) were applied and yield of reaction increased to 97%. The kinematic viscosities and densities satisfied the standards.