Synthesis of biodiesel from kapok (Ceiba pentandra L.) seed oil through ultrasound-enhanced transesterification reaction

Abstract

Biodiesel is among the prospective renewable energy due to its superior properties as fuel such as environment friendly, non-toxic, biodegradable, resulting low pollutant emission, having high energy value and high cetane number, as well as can be readily applied in diesel machine. Biodiesel is also among the priority in the Indonesian national blue print on new and renewable energy development 2005-2025. Currently, Biodiesel is commonly produced through alkaline-catalyzed transesterification of vegetable oil which is conducted in conventional batch reactor. However, this process shows several drawbacks for instance the low reaction conversion. To overcome this challenge, process intensification of biodiesel production using ultrasound-enhanced transesterification process in batch reactor was employed in this work. The feedstock used for biodiesel synthesis in this work was kapok (Ceiba pentandra L.) seed oil. The oil contains gum and high free fatty acid (FFA) as much as 8.89%. Therefore, prior to the transesterification reaction, two steps of pretreatment processes i.e. degumming process for gum removal and esterification for reducing the FFA content until it reaches the value below 2%. The main transesterification reaction was then performed by using ultrasound enhanced batch reactor which was operated at the frequency of 20 Hz and temperature of 60℃ in the presence of KOH catalyst. The reaction time was fixed 60 minutes. On the other hand, the molar ratio of methanol to oil was varied at 1:4, 1:5 and 1:6, and the catalyst concentration was studied at 0.5, 1, and 1.5% w cat/ w oil. It was found that highest yield was obtained at the reaction conducted using 0.5% catalyst and the molar ratio of 1.6 with the reaction conversion of 99.82%. This result was higher than the yield resulted by the conventional process performed at the similar condition which revealed the yield of 90%. Biodiesel produced using ultrasound-enhanced reactor fulfilled the SNI standard of properties in term of viscosity and density.