Analysis of Alkaline Catalyzed Transesterification of Palm Oil in Presence of Ultrasound Irradiation and Quality Evaluation of Biodiesel

Abstract

Abstract

In this study the irradiation of ultrasound energy on transesterification of palm oil was investigated. Furthermore, the main properties of the pure biodiesel produced under ultrasound irradiation were investigated. Response surface methodology (RSM) through the Central Composite Design (CCD) was applied to evaluate and optimize the influence of temperature (50 to 64˚C), methanol to oil (MeOH:Oil) molar ratio (6:1 to 12:1), catalyst concentration (1 to 2wt%), ultrasound power (300 to 400w) and reaction time (20 to 60min) on reaction yield. One of the key findings is the maximum yield of 93.84% was achieved during 20 minutes of reaction.  Besides, the analysis of the operating conditions indicate that the reaction temperature, MeOH:Oil molar ratio and catalyst concentration were the most important variables on reaction yield while ultrasonication could speed up the reaction and decrease the time. The experimental results showed that ultrasound assisted transesterification could improve the density of biodiesel by about 0.3 kg/m³, the viscosity by 0.12 mm²/s, the pour point by about 1~2 ˚C and the flash point by 5˚C compared to the traditional conventional heating. A mathematical representation for biodiesel yield was then successfully generated. Based on the model in the optimum situation, temperature of 64˚C, MeOH:Oil molar ratio of 9:1, catalyst concentration of 1.7wt% and irradiation amplitude of 372 produced reaction yield of 95.83% between 33 to 35 min from the start of the reaction. Finally, the physical and chemical properties of the products met the ASTM standard.