Process analysis and phase equilibria for the removal of chemicals from fatty oils using near-critical solvents

dThe use of near-critical CO2 and propane for the removal of chemicals-poll utants, undesirable or valuable products-from fatty oils is studied. The pr ocess conditions are discussed, on the basis of phase equilibrium predictio ns from a group contribution equation of state. The extension of the equati on to cover systems with large differences in molecular size requires the u se of revised parameters. With the new parameters, a good correlation of ph ase equilibrium data for all of the binaries involved in the process was ac hieved. Distribution coefficients of different chemicals between the oil an d solvent phases were predicted, and optimum process conditions were explor ed. The extraction with propane requires the operation above the lower crit ical endpoint temperature of the binary fatty oil-propane system, to have l iquid-liquid or liquid near-critical fluid phase immiscibility. The process analysis indicates that there are optimum operating pressures that minimiz e solvent requirements and fatty oil losses in the extract.