Energy and Power Engineering, 2015, 7, 135-143
Published Online April 2015 in SciRes. http://www.scirp.org/journal/epe
http://dx.doi.org/10.4236/epe.2015.74013
How to cite this paper: Okullo, A.A. and Temu, A.K. (2015) Modelling the Kinetics of Jatropha Oil Transesterification. Energy
and Power Engineering, 7, 135-143. http://dx.doi.org/10.4236/epe.2015.74013
Modelling the Kinetics of Jatropha Oil
Transesterification
Aldo A. Okullo
1
, Abraham K. Temu
2
1
Department of Chemistry, Faculty of Science, Kyambogo University (KYU), Kampala, Uganda
2
Department of Chemical and Mining Engineering, University of Dar Es Salam (UDSM),
Dar Es Salaam, Tanzania
Email: okulloapita@yahoo.com , Atemu8@yahoo.com
Received 10 October 2014; accepted 8 April 2015; published 10 April 2015
Copyright © 2015 by authors and Scientific Research Publishing Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Abstract
Kinetics of a chemical reaction provides an important means of determining the extent of the re-
action and in reactor designs. Transesterification of jatropha oil with methanol and sodium hy-
droxide as a catalyst was conducted in a well mixed reactor at different agitation speeds between
600 and 800 rpm and temperature range between 35˚C and 65˚C. The effect of variation of tem-
perature and mixing intensity on rate constants were studied. The initial mass transfer controlled
stage was considered negligible using the above impeller speeds and second order mechanism
was considered for the chemically controlled kinetic stage. Samples were collected from the re-
action mixture at specified time intervals and quenched in a mixture of tetrahydrofuran (THF) and
sulphuric acid. The mixture was centrifuged at 2000 rpm for 15 minutes and the methyl ester was
separated from the glycerol. The ester was washed with warm water (50˚C), dried and analysed
using gas chromatography coupled with flame ionization detector (GC/FID) to determine free and
total glycerine and methyl ester. A mathematical model was fitted using second order rate law.
High temperature and high mixing intensity increased reaction rates. The model fitted well with a
high correlation coefficient (R
2
) of 0.999.
Keywords
Second Order Kinetics, Rate Constants, Jatropha Oil, Transesterification
1. Introduction
Biodiesel is produced from plant oils and animal fats. Production of biodiesel has become widespread because