Modeling high-pressure vapor–liquid equilibrium of limonene, linalool and carbon dioxide systems (original) (raw)
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Modelling High-Pressure Vapor-Liquid Equilibrium of Limonene, Linalool and CO2 Systems
Journal of Supercritical Fluids The
The research reported in this study is focused on modeling high-pressure phase behavior for CO 2-limonene and CO 2-linalool. A modified Peng-Robinson equation of state was applied to calculate vapor-liquid equilibrium using five different mixing rules obtained by incorporating activity coefficient models. The methodologies proposed by Heidemann-Kokal, Wong-Sandler and LCVM were used coupled with NRTL, UNIQUAC and UNIFAC models. A comparative analysis of the generated models was done for the binary systems and the best model was chosen to describe phase behavior of the system CO 2-limonene-linalool. An isothermal flash calculation was applied to investigate selectivity and yield simultaneously for this ternary system in order to understand better the process parameters governing supercritical CO 2 deterpenation of citrus peel oil. The results showed that to obtain good separation between limonene and linalool at 50°C and pressures from 80 to 90 bar a high CO 2 /oil ratio is needed. As this ratio decreases, the process can be operated at 60 and 70°C over the same pressure range with equivalent performance.
The Journal of Supercritical Fluids, 2005
The high-pressure phase behavior of the ternary system carbon dioxide + limonene + linalool was determined experimentally by a synthetic method. All the experiments were carried out in an approximately constant molar concentration of carbon dioxide equal to 98.00%. The ratio of limonene to linalool was varied from 0 to 1 through 12 different concentrations. Under these conditions, no liquid-liquid immiscibility was observed for this system. The data included bubble points, critical points and dew points within a temperature and pressure range of 293-349 K and 5-14 MPa, respectively. The results were compared with ternary data of ethane + limonene + linalool at similar conditions of constant supercritical fluid concentration and varying limonene to linalool ratios. The results indicated that supercritical extraction of citrus oils could be carried out at lower pressures if ethane is used instead of carbon dioxide.
High Pressure Solubility Data of the System Limonene + Linalool + CO 2
Journal of Chemical and Engineering Data, 2001
The feasibility of deterpenating orange peel oil with supercritical CO 2 depends on relevant vapor-liquid equilibrium data because the selectivity of this solvent for limonene and linalool (the two key components of the oil) is of crucial importance. In this work the solubility data for the CO 2 + limonene + linalool ternary system were measured at (318.2 and 328.2) K. The range of pressures covered was from (70 to 110) bar. Two different mixtures of limonene + linalool were used: a 40 mass % limonene + 60 mass % linalool mixture and a 60 mass % limonene + 40 mass % linalool mixture. To correlate the obtained results, two equations of state were successfully used (Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK)). * Corresponding author. Fax: +34 96 386 48 98. Telephone: 34 96 986 43 16.
High-pressure vapor-liquid equilibrium data for CO2-orange peel oil
Brazilian Journal of Chemical Engineering, 2000
Abstract-Recently, there has been a growing interest in fractionating orange peel oil by the use of supercritical carbon dioxide (SCCO 2). However, progress in this area has been hindered by the lack of more comprehensive work concerning the phase equilibrium ...
Modelling of the phase behaviour for vegetable oils at supercritical conditions
The Journal of Supercritical Fluids, 2009
This work describes a generalized procedure for high pressure equilibrium calculations for terpene oils. A simple semiempirical model allows the prediction of the solubilities of essential oils at high pressure on the basis of the physicochemical properties of their compounds (molecular weight, boiling temperature, density, and solubility parameter). This easy model can be useful for the determination of the fractionation and for the preliminary scale-up and economic evaluation. The theoretical basis considers any essential oil composed of two types of components: oxygenated and nonoxygenated. Vapor−liquid equilibrium data of binary systems (terpenoids/CO 2 ) are used to correlate the semiempirical model proposed. Validity of the prediction is checked by comparison with literature data concerning ternary systems (limonene + linalool + CO 2 ) and real mixtures (lemon and orange oils + CO 2 ). Finally, the simulation and optimization of a countercurrent column for the fractionation of terpenes from lemon oil are performed.
RSC Advances, 2013
The knowledge of thermodynamic properties such as the heat of mixing or the heat capacity is very important for the correct design and the optimisation of separation processes. This paper describes thermal effects associated with the supercritical carbon dioxide extraction and fractionation of eucalyptus and citrus essential oils. In particular, the excess molar enthalpies (H E m ) for the binary mixtures CO 2 + citral and the ternary mixtures CO 2 + 1,8-cineole + limonene were measured at conditions of temperature and pressure typically used in these techniques. Values for both systems were exothermic over the entire range of composition, exhibiting a very exothermic minimum in the CO 2 -rich region due to the change of state of carbon dioxide from that of a low-density fluid to that of a liquid-mixture composition. Data were analysed in terms of phase equilibria and critical parameters as well as densities of pure components and their mixtures. Cubic equations of state were used to model data, values for the ternary mixtures were satisfactorily predicted using binary data for the three related binary systems. Thermal effects reported in this publication and in previous work for binary mixtures formed by supercritical CO 2 and the key components of eucalyptus and citrus essential oils (1,8-cineole, limonene, linalool and citral) were compared and analysed in terms of CO 2 -terpene interactions. In the case of 1,8-cineole and limonene, values for the temperature increments due to their mixing with carbon dioxide were estimated and found to be of considerable magnitude.
Liquid–vapor and liquid–liquid–vapor equilibria in the ternary system ethane+limonene+linalool
The Journal of Supercritical Fluids, 2005
To investigate the potential of replacing supercritical carbon dioxide by supercritical ethane in the deterpenation of citrus essential oils, the phase behavior of the ternary system ethane + limonene + linalool was determined experimentally. The measurements were made with a synthetic method in which at any desired temperature, the pressure was varied for a mixture of fixed overall concentration, until a phase change was observed visually. The molar concentration of ethane was fixed at a constant value of 98% in all the experiments, leaving the ratios of limonene to linalool as variables ranging from 0 to 1. Equilibria between the vapor and liquid phases were measured within temperature and pressure ranges of 293-363 K and 3-9 MPa, respectively. It was observed that limonene had higher solubility than linalool in supercritical ethane, with the difference in solubility increasing with temperature. In contrast to the ternary system with carbon dioxide, the ternary system with ethane, limonene and linalool exhibited liquid-liquid phase splitting, resulting in the presence of a three-phase liquid-liquid-vapor region. This occurred in the linalool-rich side of the phase diagram. Experimental values of the upper and lower critical endpoints of the three-phase region, in addition to normal critical points of two-phase equilibria are presented. From the experimental results, it can be concluded that the system ethane + linalool + limonene shows type-V fluid phase behavior according to the classification of van Konynenburg and Scott.
PROCESS OPTIMIZATION FOR SUPERCRITICAL CONCENTRATION OF ORANGE PEEL OIL
2005
This work addresses modeling, simulation and optimization of countercurrent deterpenation of orange peel oil, modeled as a model mixture of limonene-linalool, with supercritical carbon dioxide as solvent. Binary and ternary systems are modeled with a group contribution equation of state, and vapor-liquid equilibria and selectivity predictions are compared to experimental data from different sources. A nonlinear programming model is proposed for the maximization of net profit. Process simulations are carried out at conditions reported in the literature and component purity and recovery in the output streams are contrasted against laboratory-scale process results. Optimization results provide operating conditions and equipment size to maximize net profit.
Phase equilibria of oleic, palmitic, stearic, linoleic and linolenic acids in supercritical CO2
Brazilian Journal of Chemical Engineering, 2009
The knowledge of the phase equilibrium is one of the most important factors to study the design of separation processes controlled by the equilibrium. Fatty acids are present in high concentration as byproducts in vegetable oils but the equilibrium data involving these components is scarce. The objective of this work is the experimental determination of the liquid-vapor equilibrium of five binary different systems formed by carbon dioxide and palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). The equilibrium experimental data was collected at 40, 60 and 80ºC at 60, 90 and 120 bar, at the extract and raffinate phases, using an experimental apparatus containing an extractor, a gas cylinder and pressure and temperature controllers. The data was modeled using the cubic equation of state of Peng-Robinson with the mixing rule of van der Waals with binary interaction parameters. The model was adequate to treat the experimental data at each temperature and at all the temperatures together. The best model that includes the van der Waals mixing rule with two parameters has maximum deviation of 17%. The distribution coefficients were also analyzed and it was concluded that the fractionation of the fatty acids is possible using supercritical carbon dioxide.
Chemical Engineering Science, 2008
A thermodynamic model based on the Peng-Robinson equation of state was developed in order to perform high-pressure phase equilibria calculations for the system carbon dioxide-lemon essential oil. The multicomponent natural oil was simulated by a mixture of three key components, one for each relevant class of compounds (monoterpenes, monoterpene oxygenated derivatives and sesquiterpenes). Firstly the proposed model was validated on semi-batch experimental data and then it was used to simulate the behaviour of a continuously operated countercurrent column. Experiments on deterpenation process on a packed column, operating as a stripping section, were carried out in the temperature range 50-70 • C and pressure range 8.7-11.2 MPa. The comparison between experimental results and process simulation demonstrated that the proposed model is capable of reliable predictions on the behaviour of the countercurrent continuous deterpenation process. Furthermore, an average height equivalent to a theoretical plate of about 40 cm was estimated, for the stated packing and operating conditions. A case study for the production of 10-fold high quality oil, with strict specifications for the recovery of oxygenated compounds (99%), was investigated by simulations of a continuous countercurrent process with an external reflux. The linkage between the number of theoretical stages, the reflux ratio and the solvent to feed ratio was investigated throughout the above-mentioned pressure and temperature ranges. Operating conditions at higher pressure and temperature proved to be more favourable. As an example, operating a 20 theoretical stage column at 70 • C and 11.2 MPa, it is possible to attain process specifications with a solvent to feed ratio of about 63. ᭧