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 p eel oil. To understand the behavior of this multicomponent system, phase eq uilibrium measurements, countercurrent column experiments and flooding-poin t measurements were carried out. Conditions were set within a temperature r ange from 323 to 343 K and pressures from around 8 MPa up to 13 MPa. Separa tion 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 experime nts were used to study the influence of product composition on both selecti vity and mutual solubility. A stage calculation method based on the Janecke diagram was applied to evaluate VLE data. Due to the fact that the operati ng costs of a continuous process depend on the solvent-to-feed ratio, this parameter was used to determine the optimal conditions for multistage extra ction. For a given separation task at a fixed temperature, the required sol vent-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 se paration 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.