Phase Equilibrium Measurements for the System Clove (Eugenia caryophyllus) Oil + CO₂

Abstract

Phase equilibria data for the system formed by clove oil + CO 2 were measured at pressures from 58.3 to 108.1 bar and temperatures of 303.2, 313.2, and 328.2 K. The phase equilibrium experiments (cloud points) were performed using a high-pressure variable-volume view cell. The phase transitions were visually recorded as bubble or dew points. The clove oil used in the present work was extracted with carbon dioxide at 150 bar and 298.2 K, and it consisted of a mixture of the following mass fractions: eugenol (75.5%), β-caryophyllene (12.1%), eugenol acetate (11.0%), and R-humulene (1.40%). Liquid-liquid-vapor equilibria were observed at 303.2 and 308.2 K, and liquid-vapor equilibria were observed at 313.2, 318.2, and 328.2 K. The phase equilibria data were modeled assuming the system to be a pseudobinary system. The Peng-Robinson equation of state with the quadratic mixing rule was used. The experimental data were fitted using the simulated annealing minimization method. Two different procedures were employed: (i) the phase stability was calculated using the Helmholtz free energy and the interval analysis, and (ii) the phase equilibrium was calculated using the Gibbs free energy, which was solved with the simulated annealing method. The model described quantitatively the experimental data.

Phase stability analysis of liquid-liquid equilibrium with stochastic methods

“…Furthermore, it is also essential to start from a conveniently high temperature in order to allow a more detailed exploration of the solution space of the problem. Over the past years the SA algorithm has been applied to several types of phase equilibrium calculation problems involving phase stability tests and flash equilibrium calculations by minimizing the Gibbs free energy (Zhu and Xu, 1999;Zhu et al, 2000;Rangaiah, 2001;Teh and Rangaiah, 2003;Corazza et al, 2004;Souza et al, 2004;BonillaPetriciolet, 2006) and parameter estimation of thermodynamics models (Henderson et al 2001;Moura et al, 2005;Carvalho Jr., 2006;Franceschi et al, 2006). Preliminary studies indicated that the best values for phase stability calculations are 0 A T 1000.0 = , 0.9 α = and 10000 ζ = .…”

Application of interval analysis for gibbs and helmholtz free energy global minimization in phase stability analysis

“…The approach used in this paper was applied to describe the phase equilibrium behavior of the clove oil + CO 2 system, using experimental data from Souza et al (2004). The main characteristic of this system, formed of an essential oil and carbon dioxide, is the large variety of different types of chemical groups found in the essential oil, which is in fact a complex system.…”

“…It can be seen that the model was able to fit the experimental data for the clove oil + CO 2 system reasonably well. The values for the fitted parameters (k 12 , l 12 ) as well as the critical properties and the accentric factors were determined by Souza et al (2004). …”

Phase Behavior at High Pressure of the Ternary System: CO2, Ionic Liquid and Disperse Dye

“…The experimental apparatus and experimental procedure are similar to those used in previous studies of phase equilibrium carried out by our group [20][21][22]. Briefly, the experiment begins with the introduction of a predetermined amount of compounds (CO 2 , IL, and dye) in the equilibrium cell so that the global composition of the mixture is known.…”