Fractional Extraction with Supercritical Carbon Dioxide for the Removal of Terpenes from Citrus Oil

摘要

Fractional extraction with supercritical carbon dioxide was studied for the preparation of terpeneless citrus oil using a 9 mm i.d. and 1.0 m long packed column with an axial temperature gradient of 0-20 K. The separation of citrus oil model mixture, which consists of limonene, linalool, and citral, was investigated at various column temperature distributions of 313-333 K, pressures of 8.8-11.8 MPa, and CO_2 flow rates of 0.091-0.512 g/s. The selective separation was performed due to the internal reflux in the column induced by an axial temperature gradient. A little increase in pressure or CO_2 flow rate accelerated the extraction rate without decreasing the selectivity. Raw orange oil was processed successfully at a temperature gradient of 20 K, from 313 K at the bottom to 333 K at the top of the column, and a pressure of 8.8 MPa.