Prediction of biodiesel yield during transesterification process using response surface methodology

Abstract

This study examines the production of biodiesel from vegetable palm oil (VPO) via transesterification catalyzed by calcium oxide modified with titanium dioxide (CaO-TiO2) under UV light. Response surface methodology (RSM) with central composite design (CCD) was used to optimize the biodiesel yield. The optimized conditions for transesterification were 2.52 wt.% for catalyst dosage, 3:4 for volumetric ratio of VPO to methanol, 65 °C for reaction temperature, and 145.51 min for reaction time. VPO transesterification under optimum conditions produced 96.67% biodiesel yield. In addition, regeneration of CaO-TiO2 catalyst was studied under optimum conditions. This catalyst can be reused for four times with biodiesel yields beyond 80%. GC-MS analysis revealed the main methyl ester components in the biodiesel product including 9-octadecenoic acid, methyl ester (E)-(oleic acid) and hexadecanoic acid methyl ester (palmitic acid). Kinetic viscosity and higher heating value of the biodiesel were found to be in agreement with the ASTM D 6751 standard. This study demonstrated a practical method to produce biodiesel from VPO with less corrosion, less toxicity, and less environmental problems using an effective, stable and economic heterogeneous basic catalyst, CaO-TiO2.