Sub-critical carbon dioxide extraction of the hexane extract of the leaves of Tasmannia lanceolata

The extraction of Tasmannia lanceolata concrete using liquid CO₂ at sub-critical conditions of pressure and temperature was investigated. A pilot-scale extractor was modified to include a second liquid metering pump for the recycling of the re-condensed CO₂. Phase equilibrium was the controlling thermodynamic element in the rate of oil extraction while mass balance transfer dominated the solubilities of lower molecular weight, non-polar individual components. Polygodial, as the heaviest and highest oxygenated component, had a different apparent solubility to the lower monoterpenes and a solubility minimum was observed for this di-aldehyde at pressures in the order of 110 bar and at temperatures of 20°C to 24°C. The large variation in density associated with liquid carbon dioxide as it approaches critical temperature and pressure provides for higher selectivity of extraction.