Biodiesel by Transesterification of Rapeseed Oil Using Ultrasound: A Kinetic Study of Base-Catalysed Reactions

José María Encinar, Ana Pardal, Nuria Sánchez and Sergio Nogales
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José María Encinar: Department of Chemical Engineering and Physical Chemistry, Extremadura University, Avenida de Elvas s/n., 06071 Badajoz, Spain
Ana Pardal: Department of Applied Sciences and Technology, IP Beja, Rua Pedro Soares s/n., 7800 Beja, Portugal
Nuria Sánchez: Department of Chemical Engineering and Physical Chemistry, Extremadura University, Avenida de Elvas s/n., 06071 Badajoz, Spain
Sergio Nogales: Department of Chemical Engineering and Physical Chemistry, Extremadura University, Avenida de Elvas s/n., 06071 Badajoz, Spain

Energies, 2018, vol. 11, issue 9, 1-13

Abstract: The objective of this work was to study the acceleration that ultrasound causes in the rate of biodiesel transesterification reactions. The effect of different operating variables, such as ultrasound power, catalyst (KOH) concentration and methanol:oil molar ratio, was studied. The evolution of the process was followed by gas chromatography, determining the concentration of methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, saponification and iodine values, acidity index, water content, flash and combustion points, cetane index and cold filter plugging point (CFPP), according to EN 14214 standard. High methyl ester yield and fast reaction rates were obtained in short reaction times. Ultrasound power and catalyst concentration had a positive effect on the yield and the reaction rate. The methanol:oil molar ratio also increased the yield of the reaction, but negatively influenced the process rate. The reaction followed a pseudo-first order kinetic model and the rate constants at several temperatures were determined. The activation energy was also determined using the Arrhenius equation. The main conclusion of this work is that the use of ultrasound irradiation did not require any additional heating, which could represent an energy savings for biodiesel manufacture.

Keywords: fatty acid methyl ester; catalyst; viscosity; iodine value; acidity index (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (9)

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