Research Summary: The objective of this project is to determine the fundamental mechanisms governing the transport of binary and ternary mixtures of oleic and linoleic acids and their methyl esters into supercritical carbon dioxide using a specially designed wetted wall column. Phase equilibria of the biomaterials will be measured using previously developed apparatuses designed for this purpose. The gas and liquid film mass transfer coefficients will be calculated as a function of temperature and pressure. The applicability of existing correlations for mass transfer to conditions above the critical point of the pure solvent will be tested. An attempt will be made to generalize the theory of mass transfer of large bio- molecules into supercritical solvents and in expanded liquid mixtures. Innovation/Novelty: The proposed work will be the first rigorous attempt to measure supercritical fluid-fluid mass transfer parameters under carefully defined conditions. In wetted wall columns, no bubbles form or coalesce, no froth forms and mass transfer area can be controlled. Moreover, models simulating the behavior of wetted wall columns are currently at a high stage of sophistication, thereby giving a sound theoretical framework to correlate the data. Although the use of wetted wall columns at low pressure in gas absorption/stripping and liquid-liquid extraction is widespread and its utility in obtaining fundamental data is widely recognized, this would be the first effort to construct a workable wetted wall column for use with supercritical solvents at pressures up to 350 atmospheres. Technical and Practical Significance: In addition to the inherent value of the phase equilibrium data for characterizing the behavior of biomaterials in supercritical solvents, the proposed research will yield high quality data for mass transfer coefficients through known interfacial mass transfer area. The functionality of mass transfer coefficients with pressure and temperature can then be profitably used on a theoretical as well as practical level as a guide in determining mass transfer rates and optimal operating conditions for supercritical fluids in packed, tray and bubble columns.
