Research article Optimisation of solid liquid extraction of jatropha oil using petroleum ether Sepidar Sayyar, 1 Zurina Zainal Abidin 1,2 * and Robiah Yunus 2 1 Department of Chemical and Environmental Engineering, Faculty of Engineering, 43400 Serdang, Selangor, Malaysia 2 Institute of Advanced Technology, UPM, 43400 Serdang, Selangor, Malaysia Received 19 October 2011; Revised 31 January 2012; Accepted 22 April 2012 ABSTRACT: Jatropha curcas I. is an oil-bearing seed plant with a wide range of applications. The oil from the seeds of this plant has been used as an industrial raw material for many years. One of the important characteristics of jatropha oil is its potential for fuel and biodiesel production to meet the global energy demand. In this paper, solid–liquid extraction of jatropha oil from seeds using petroleum ether was optimised on the basis of the amount of the extracted oil. Four main factors, namely temperature, the solvent-to-solid ratio, the reaction time and the size of the raw material, were investigated to optimise extraction conditions for achieving the highest oil yield under experimental conditions. The kinetics of the extraction using petroleum ether as the solvent were also studied and fitted to a second-order model. The free fatty acid (FFA) content of the oil was used as an index of the oil quality. The optimum conditions were found to be 7 h of reaction time, a temperature of 68  C, a coarse particle size of 0.5–0.75 mm and a solvent-to-solid ratio of 6 : 1. Storing the ground seeds for one week before extraction had a remarkably negative effect on the quality of the oil produced (FFA  6.99%), whereas the quality of the oil was satisfactory when extracted from the seeds immediately after grinding (FFA  0.62%). The experimental data fitted well to the second-order model with the saturation extraction capacity and the initial extraction rate increasing with increasing temperature. Copyright © 2012 Curtin University of Technology and John Wiley & Sons, Ltd. KEYWORDS: jatropha; extraction; petroleum ether; biodiesel INTRODUCTION The demand for fuel for transportation is growing in most countries in spite of the current energy crisis. There is a growing need to find alternative substitutes for petrochemical-based fuels; one of these efforts is the use of vegetable oils as fuels or fuel sources. The non-edible oil produced from jatropha curcas has tremendous potential to be used not only directly as fuel but also as a source for biodiesel production. [1–4] Jatropha curcas is an oil-bearing seed plant with a wide range of applications. Extracts from this species have been shown to have an anti-tumour activity: [5] its oil can be used as an engine lubricant, [6] and its leaves can be used as a remedy for malaria and high fever. [3,6] Moreover, this plant can be used as an ornamental plant, a raw material for producing dye, a potential feed stock, a pesticide, a soil enrichment addi- tive and, more importantly, as an alternative fuel. [1–4] A mechanical method is widely used in the oil extrac- tion process whereby the oil-bearing seeds are subjected to a high shear stress and pressure. Typical mechanical machines are the ram spindle and the screw press. [7,8] Although mechanical methods have a lower production cost compared with other techniques, however, they give a lower oil recovery. [8] Aqueous enzymatic extrac- tion is another method employed to extract oil and fats from jatropha seeds. Unlike its competitors, aqueous enzymatic extraction is eco-friendly, does not require extensive energy for solvent separation and has less fire/explosion risks. Several researchers have exploited various enzymes to extract jatropha oil. [9–11] Enzymatic extraction has also been combined with ultrasound [10] and three-phase partitioning [12] to enhance oil recovery. Recently, reactive extraction has been demonstrated whereby extraction and transesterification processes were performed in a single step. [13,14] This method has the advantages of reducing time, cost and the amount of solvent used. Solid–liquid extraction is normally employed to extract oil for biodiesel production. [2,15,16] Solid–liquid extraction, otherwise known as leaching, involves the transfer of a soluble fraction (the solute or leachant) from a solid material to a liquid solvent. Normally, *Correspondence to: Zurina Zainal Abidin, Department of Chemi- cal and Environmental Engineering, Faculty of Engineering, UPM, 43400 Serdang, Selangor, Malaysia. E-mail: zurina@eng. upm.edu.my © 2012 Curtin University of Technology and John Wiley & Sons, Ltd. Curtin University is a trademark of Curtin University of Technology ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING Asia-Pac. J. Chem. Eng. 2013; 8: 331–338 Published online 31 May 2012 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/apj.1664