ALTIN MELE, MARIZA ANDONI, ARDITA MELE1, ELVA DURO, JETA LICA, LORENCI GJURGJAJ, ISUELA KARÇINI, ANTONINA MEMA
Abstract
High pressure phase equilibria measurements are important in several industrial applications where pure substances or mixtures thereof coexist in different phases (McHugh et al., 1983). Determination of the phase’s composition and density (or molar volume) at certain temperatures and high pressures is shown in this study to be carried out in a high pressure steel apparatus equipped with calibrated measurement instruments. In the carbon dioxide – ethanol – water mixtures, the chemical composition of coexisting liquid and gaseous phases is done using difference weighing for the carbon dioxide mole fraction before and after its release, and pycnometers for the remaining ethanol-water mixtures. Measurements of the P-V-T-x Data in the CO2-EtOH-H2O system were carried out in this high-pressure apparatus at 10.2 MPa and three different temperatures 308.15 K, 333.15 K and 353.15 K. The results were presented in a molar volume – composition diagram. At 308.15 K, this ternary system shows an equilibrium between a CO2-rich and a H2O-rich liquid phase, running from the CO2-H2O binary system to a common critical point. Liquid and gas phases coexist in the ternary system at 333.15 K and 353.15 K. The gas phase shows molar volumes and composition running from the CO2-rich phase of the CO2-H2O to the CO2-EtOH binary system, while in the liquid from H2O-rich to the EtOH-rich phases of the same binary systems.
Key words: High pressure phase equilibria, CO2-EtOH-H2O, molvolume- concentration diagram.