High-pressure apparatus for phase equilibria studies:: solubility of fatty acid esters in supercritical CO2

Starting from a screw-type manual pump, a high-pressure variable-volume view cell was designed to perform static measurements of equilibria involving CO2 and fatty acid esters. Though the design of the cell allows both the upper and the lower phases to be sampled, the synthetic method was chosen for this study. The efficiencies of both the apparatus and the method were first checked through preliminary experiments related to a compound already studied, namely methyl oleate. The good agreement between our measurements and those published in the literature allowed us to study other compounds, more precisely the ethyl esters of myristic, palmitic and stearic acids. These measurements were obtained at three different temperatures, 313.15, 323.15 and 333.15 K, and at pressures ranging from 1 to 18 MPa. The data were correlated using the modified Peng-Robinson equation of state with the classical quadratic mixing rules. An interesting feature of the apparatus is its low consumption of substance for a rather large amount of acquired data. (C) 1999 Elsevier Science B.V. All rights reserved.