Phase equilibria for the ternary system methyl oleate + tocopherol + supercritical CO₂

To study the feasibility of using supercritical CO₂ to concentrate natural tocopherols from soybean oil deodorizer distillate (DOD), we measured the ternary phase equilibrium data for methyl oleate + α-tocopherol + supercritical CO₂ from (313.15 to 363.15) K in the pressure range from (10 to 29) MPa. The measured data were well correlated using the Soave-Redlich-Kwong EOS with the Adachi-Sugie mixing rule. The separation factor between methyl oleate and tocopherol in CO₂ was investigated. On the basis of these results, equilibrium lines in the experimental ranges were obtained that provide fundamental data for concentrating tocopherols with supercritical CO₂. In addition, because the distribution of tocopherol in supercritical CO₂ increases markedly because of the abundance of methyl oleate, methyl oleate was shown to act as a cosolvent for tocopherol. Finally, according to the obtained results, a strategy for a separation operation was suggested. Visual observation also provided information useful in further experiments and design.