Countercurrent deterpenation of citrus oils with supercritical CO2

The separation of terpene hydrocarbons from oxygenated aroma components was investigated by using supercritical carbon dioxide to fractionate orange peel oil. To understand the behavior of this multicomponent system, phase equilibrium measurements, countercurrent column experiments and flooding-point measurements were carried out. Conditions were set within a temperature range from 323 to 343 K and pressures from around 8 MPa up to 13 MPa. Separation factors for the two groups of oil components, 'terpenes' and 'aroma', were obtained for the system CO2 + orange peel oil depending on temperature and pressure. Moreover, fractionated products from countercurrent experiments were used to study the influence of product composition on both selectivity and mutual solubility. A stage calculation method based on the Janecke diagram was applied to evaluate VLE data. Due to the fact that the operating costs of a continuous process depend on the solvent-to-feed ratio, this parameter was used to determine the optimal conditions for multistage extraction. For a given separation task at a fixed temperature, the required solvent-to-feed ratio was found to decrease with increasing pressure. This is explained by the increase in loading of the solvent and the possibility of enhancing the extract reflux which predominates the effect of decreasing separation factors at a higher loading. After passing a minimum, the required solvent-to-feed ratio increases near the critical point of the mixture. (C) 1999 Elsevier Science B.V. All rights reserved.