Comparison of the Performances of Hydrodistillation and Supercritical CO2 Extraction Processes for Essential Oil Extraction from Rosemary (Rosmarinus Officinalis L.)

Abstract

In order to compare the extraction performances of two different techniques, essential oil was extracted from leaves of local rosemary by means of hydrodistillation and supercritical CO₂ extraction. However hydrodistillation is traditionally the most used one.
In the present work experiments were performed using a Clevenger-type apparatus well equipped to maintain the mass ratio plant/water to its initial level. The system was operated at atmospheric pressure, with a flow condensation rate of 4.5ml/min and a ratio plant/water of 1/10.
Supercritical fluid extraction runs were carried out using a dynamic extraction unit at the operating conditions of 100 bars for the pressure, 40°C for the temperature and 7g/min for the solvent flow rate.
In both methods the only parameter that was varied is the particle size, in order to investigate its effect on the processes.
The obtained extraction yields were 2.5 and 1.94% for the supercritical CO₂ extraction and the hydrodistillation, respectively. The results confirmed that the particle size had an important effect on the two processes where a decrease of the diameter enhanced mass transfer leading to better extraction yields. However hydrodistillation took at least two hours less time than Supercritical CO₂ extraction for a same essential oil extraction degree.