Phase Equilibrium Engineering of Jojoba Oil Extraction with Liquid CO2+Propane Mixtures

CAMILA A. PALLA; PABLO HEGEL; SELVA PEREDA; GUILLERMO MABE; ESTEBAN BRIGNOLE

Puerto Varas

Congreso; Equifase 2012- IX IBEROAMERICAN CONFERENCE ON PHASE EQUILIBRIA AND FLUID PROPERTIES FOR PROCESS DESIGN; 2012

Facultad de Ingeniería, Universidad de Concepción

Jojoba oil is an important ingredient of many cosmetic and hair care products that is composed by monounsaturated esters of high molar mass. It is a liquid wax extracted from the seeds of Jojoba plant (Simmondsia chinensis) by mechanical pressing, followed by a solvent extraction of the pre-pressed Jojoba meal with hexane [1]. Health and environmental concern associated with the use of solvents like hexane have place new demands on cosmetic and pharmaceutical industry to invest in clean technologies such as the Supercritical Fluid Extraction with solvents like CO2 and propane [2]. The supercritical extraction of jojoba oil by scCO2 has been studied previously in the literature [3-5]. Stahl et al. [3] reported that the solubility of jojoba oil changes with temperature and pressure in the range of 293 K to 353 K and 100 bar to 2600 bar. High pressures (300 bar to 700 bar) are required in order to obtain good solubility and extraction yields because jojoba oil has partial miscibility with CO2 in liquid and supercritical state. The addition of co-solvents like hexane and ethanol has also been investigated to increase the oil solubility [4,5]. However, these co-solvents remain in the oil after CO2 separation and they are difficult to remove from the oil, requiring a high vacuum step to obtain a pure product at low temperatures [1] Vegetable oils show complete miscibility with liquid propane at temperatures lower than 343 K, being a good solvent for its extraction [6]. Also, like any supercritical solvent, it can be easily removed from the oil after the extraction by depressurization. The main drawback of propane is its flammability, any percentage of propane in a propane/air mixture above 2.15 vol.% will be sufficient for propane to burn. However, CO2 in a 30 % V/V in the gas mixture can be used to turn the solvent propane/CO2/air non-flammable [7]. Propane and carbon dioxide solvent mixtures have been extensively studied in previous works as supercritical or high-pressure liquid solvents for lipids and oils [2,8,9]. In this work a phase equilibrium engineering analysis has been carried out in order to select appropriate operating conditions of temperature, pressure and solvent concentration for the extraction of Jojoba oil with solvent mixtures of carbon dioxide and propane under liquid conditions. Experimental extractions of jojoba oil using both CO2 and solvent mixtures of CO2 + propane were investigated to assess the influence of the solvent composition and phase behavior on the extraction rate. The experiments were carried out at operating temperatures of 298 K and 343 K, in a range of pressure between 30 bar to 150 bar according to the solvent composition (30 wt.% to 80 wt.%), and 0.1 g/min of solvent flow-rate. From the extraction operations it was determined that the rate of oil extracted decreased with the CO2 concentration in the solvent. There is a remarkable influence of the phase behavior on the extraction yield.