Iranica Journal of Energy & Environment 3 (Special Issue on Environmental Technology): 43-49, 2012 ISSN 2079-2115 IJEE an Official Peer Reviewed Journal of Babol Noshirvani University of Technology DOI: 10.5829/idosi.ijee.2012.03.05.08 Phase Behaviour of Palm Oil Fatty Acid Components in Supercritical Carbon Dioxide Jamilul Firdaus Jamal Abd Nasir, Mohd Omar Abd Kadir, and Norhashimah Morad* Environmental Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia Abstract: In the supercritical CO 2 method of extraction of palm oil, many processes in conventional method, such as degumming, deodorization, refining and bleaching processes, are eliminated. The supercritical method allows palm oil to be extracted and fractionated simultaneously, which not only reduces the cost of processing, but also provides a more environmental-friendly processing alternative. In this research, the high-pressure phase behaviour of the binary system between supercritical carbon dioxide (SC CO 2 ) and palm oil fatty acid components were investigated. The phase transition is observed from a camera which is connected to a high-pressure variable-volume view cell. Carbon dioxide has high solvating power, nontoxic, inflammable and low critical points. The determination of phase behaviour could offer an insight to the right operating condition of palm oil supercritical fluid carbon dioxide extraction process in order to acquire the desired extraction selectivity and an optimum yield. The phase boundaries of some fatty acids components, lauric acid (C12), stearic acid (C18), and oleic acid (C18) in compressed supercritical carbon dioxide were determined at temperatures of 313.15 K, 323.15 K, 333.15 K, 343.15 K and 353.15 K under pressures between 10 MPa and 60 MPa. Key words: Fatty acid; Palm oil; Phase behaviour; Phase equilibrium; Supercritical fluid CO 2 . INTRODUCTION Supercritical extraction of vegetable oil provides a short-cut process compared to the conventional process. The steps in the phase behaviour process that was performed with binary mixtures using supercritical CO 2 can eliminate degumming process, deodorization process, refining process, and bleaching process because the oil can be extracted and fractionated simultaneously. From phase behaviour data, thermodynamic modeling can be done and some refinery process such as clarification, degumming, bleaching, and deodorization can be replaced with a single unit operation by utilizing supercritical CO 2 . Supercritical fluids are substances at pressure and temperature above their critical values. In the supercritical region of a fluid, the phase state resembles one of a dense gas with properties that are generally intermediate to those of a gas and liquid. In the supercritical state, liquid like density is approached, while viscosity is near that of normal gases, and diffusivity is about two orders of magnitude higher than in typical liquid [1]. Supercritical carbon dioxide (SC CO 2 ) has been attracting research activity around the globe due to its relatively low critical temperature (31.1 C) and critical pressure (7.34 MPa). Using SC CO 2 as a solvent, allows extraction processes to operate near ambient temperature. Furthermore, SC CO 2 is non- toxic, and can be used in food grade form for food processing, and is considered to be an environmentally friendly solvent. Several articles have been published in the application of supercritical CO 2 in palm oil and palm kernel oil processing. Bisunadan [2] examined supercritical extraction of oil from palm fruits. Extraction and fractionation of palm kernel oil has been reported by Hassan et al. [3]. The extraction of palm kernel oil using supercritical CO 2 to produce cocoa butter equivalent fat has been reported by Md Zaidul et al. [4] and Nik Norulaini et al. [5]. Studies on fatty acid phase behaviour have also been reported. Bharath et al. [6] examined phase equilibrium data of triglyceride (C24, C36, C48) CO 2 and fatty acid (C6, C12, C16) CO 2 . Chen et al. [7] measured phase equilibrium of linoleic acid, - tocopherol and triolein in supercritical CO 2 . The application of the supercritical fluid CO 2 (SF CO 2 ) has been reported as an alternative to palm oil/palm kernel oil conventional extraction process. The optimization of extraction efficiency and its selectivity generally concentrate on varying the temperature and pressure as well as the solvent modifier. *Corresponding Author: Norhashimah Morad, Environmental Technology Division, School of Industrial Technology,Universiti Sains Malaysia, Pulau Pinang, Malaysia. Tel: +6046532236, Fax: +6046573678, E-mail: nhashima@usm.my BUT 43