Phase Equilibrium Measurements for the System Fennel (Foeniculum vulgare) Extract + CO2

Abstract

Phase equilibria data for the system formed by CO2 (1) + fennel extract (2) were measured at pressures from (47.4 to 220.4) bar and temperatures of (303.0, 313.1, 323.1, and 333.0) K; CO2 mole fraction varied from (0.4827 to 0.9966). 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 fennel extract used in the present work was obtained by extraction with carbon dioxide. Liquid−vapor (LV) equilibria were observed at all temperatures for x1 = (0.4827 to 0.7086). Liquid−liquid (LL) equilibria were observed for all temperatures at x1 = (0.7178 to 0.7760) and x1 = 0.9949, except at 333.0 K; LL transition was also observed at 303.0 K and x1 = 0.9966. At 303.0 K, liquid−liquid−vapor (LLV) transitions were observed at x1 = (0.8297, 0.9273, and 0.9949); at 313.1 K for x1 = (0.9273 and 0.9949). At x1 = 0.9966 and 303.0 K, LL and LLV were observed at (98.4 and 70.2) bar, respectively. The experimental data were fitted to the Peng−Robinson equation of state with the quadratic mixing rule using the simulated annealing minimization method. The model described quantitatively the experimental data.