Mathematical modelling of supercritical CO2 extraction of volatile oils from aromatic plants (original) (raw)
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An overview of the studies carried out in our laboratories on supercritical fluid extraction (SFE) of volatile oils from seven aromatic plants: pennyroyal (Mentha pulegium L.), fennel seeds (Foeniculum vulgare Mill.), coriander (Coriandrum sativum L.), savory (Satureja fruticosa Béguinot), winter savory (Satureja montana L.), cotton lavender (Santolina chamaecyparisus) and thyme (Thymus vulgaris), is presented. A flow apparatus with a 1 L extractor and two 0.27 L separators was built to perform studies at temperatures ranging from 298 to 353 K and pressures up to 30.0 MPa. The best compromise between yield and composition compared with hydrodistillation (HD) was achieved selecting the optimum experimental conditions of extraction and fractionation. The major differences between HD and SFE oils is the presence of a small percentage of cuticular waxes and the relative amount of thymoquinone, an oxygenated monoterpene with important biological 10551 properties, which is present in the oils from thyme and winter savory. On the other hand, the modeling of our data on supercritical extraction of volatile oil from pennyroyal is discussed using Sovová's models. These models have been applied successfully to the other volatile oil extractions. Furthermore, other experimental studies involving supercritical CO 2 carried out in our laboratories are also mentioned.
Molecules, 2012
An overview of the studies carried out in our laboratories on supercritical fluid extraction (SFE) of volatile oils from seven aromatic plants: pennyroyal (Mentha pulegium L.), fennel seeds (Foeniculum vulgare Mill.), coriander (Coriandrum sativum L.), savory (Satureja fruticosa Béguinot), winter savory (Satureja montana L.), cotton lavender (Santolina chamaecyparisus) and thyme (Thymus vulgaris), is presented. A flow apparatus with a 1 L extractor and two 0.27 L separators was built to perform studies at temperatures ranging from 298 to 353 K and pressures up to 30.0 MPa. The best compromise between yield and composition compared with hydrodistillation (HD) was achieved selecting the optimum experimental conditions of extraction and fractionation. The major differences between HD and SFE oils is the presence of a small percentage of cuticular waxes and the relative amount of thymoquinone, an oxygenated monoterpene with important biological OPEN ACCESS Molecules 2012, 17 10551
Matrix effects in supercritical CO2 extraction of essential oils from plant material
Journal of Food Engineering, 2009
In this work, we reviewed the effect of the solid matrix in the supercritical CO 2 (SC-CO 2 ) extraction of essentials oils from plant material. A diffusional model was adopted that assumed the substrate is as an homogeneous solid and the partition of essential oils between the solid substrate and the SC-CO 2 phases is constant. The model was fitted to literature data from several plant materials (relevant solute identified between parenthesis): chamomile flowers (a-bisabolol), lavender flowers (camphor), oregano bracts (thymol), pennyroyal leaves and flowers (menthol), and sage leaves (1,8-cineole). Based on values of binary diffusion coefficient of the solute in the solvent (D 12 ) from a literature correlation, and the bestfit values of effective diffusivity of the solute in the solid matrix (D e ) we estimated the value of the socalled microstructural factor (MF), which is defined as the ratio between D 12 and D e which ranged from 420 for pennyroyal to 25,000 for oregano. MF encompasses several factors, mainly related with to the microstructure of the substrate, that affect the extraction rate of a solid substrate with a solvent.
2012
An overview of the studies carried out in our laboratories on supercritical fluid extraction (SFE) of volatile oils from seven aromatic plants: pennyroyal (Mentha pulegium L.), fennel seeds (Foeniculum vulgare Mill.), coriander (Coriandrum sativum L.), savory (Satureja fruticosa Béguinot), winter savory (Satureja montana L.), cotton lavender (Santolina chamaecyparisus) and thyme (Thymus vulgaris), is presented. A flow apparatus with a 1 L extractor and two 0.27 L separators was built to perform studies at temperatures ranging from 298 to 353 K and pressures up to 30.0 MPa. The best compromise between yield and composition compared with hydrodistillation (HD) was achieved selecting the optimum experimental conditions of extraction and fractionation. The major differences between HD and SFE oils is the presence of a small percentage of cuticular waxes and the relative amount of thymoquinone, an oxygenated monoterpene with important biological
2007
In this study, the supercritical carbon dioxide extraction of essential oils from plants which contain secretory ducts as essential oil reservoirs was investigated and modelled. Supercritical carbon dioxide extraction of essential oils from Asteraceae family species, marigold and chamomile, indicated that particle size had no significant influence on the extraction rate in two outermost cases: fine milled plant material and plant material cut to particle length of 5 mm. This confirmed previously reported phenomenon that in some cases particle size had no influence on the rate of supercritical extraction process. In order to explain this behavior, the mathematical model which took into consideration the phenomena occurring on the secretory duct scale, was developed and applied to simulate experimental data of marigold and chamomile supercritical carbon dioxide extraction. Proposed model was also applied to the literature experimental data of fennel fruit supercritical fluid extraction where the same phenomenon had been observed. To obtain information regarding secretory structure, scanning electron microscopy investigation of the plant material was performed. Very good agreement of the model results and experimental data in the case of different plant species, extraction conditions and particle sizes, confirmed the basic hypothesis of the model.
Supercritical carbon dioxide extraction of essential oils:: Modeling and simulation
Chemical engineering science, 1998
In this study, the supercritical carbon dioxide extraction of essential oils from plants which contain secretory ducts as essential oil reservoirs was investigated and modelled. Supercritical carbon dioxide extraction of essential oils from Asteraceae family species, marigold and chamomile, indicated that particle size had no significant influence on the extraction rate in two outermost cases: fine milled plant material and plant material cut to particle length of 5 mm. This confirmed previously reported phenomenon that in some cases particle size had no influence on the rate of supercritical extraction process. In order to explain this behavior, the mathematical model which took into consideration the phenomena occurring on the secretory duct scale, was developed and applied to simulate experimental data of marigold and chamomile supercritical carbon dioxide extraction. Proposed model was also applied to the literature experimental data of fennel fruit supercritical fluid extraction where the same phenomenon had been observed. To obtain information regarding secretory structure, scanning electron microscopy investigation of the plant material was performed. Very good agreement of the model results and experimental data in the case of different plant species, extraction conditions and particle sizes, confirmed the basic hypothesis of the model.
Extraction of Clove and Vetiver Oils with Supercritical Carbon Dioxide: Modeling and Simulation
The Open Chemical Engineering Journal, 2007
The kinetics of supercritical fluid extraction (SFE) of clove and vetiver oils using carbon dioxide as solvent was studied, in order to establish an efficient method to predict extraction curves on large scale. The mass transfer model of Sovová was used to adjust the experimental SFE data, which were obtained at 100 bar and 35 °C for clove and 200 bar and 40 °C for vetiver, using extraction columns of different geometry and solvent flow rates. Some other process parameters, such as bed density and porosity, solvent to feed ratio and solvent velocity were kept constant from one experiment to another, in order to verify if the mass transfer coefficients adjusted by the model varied. The results show that the model of Sovová was able to predict an overall extraction curve for clove from data obtained with twenty times less raw material, since the mass transfer coefficients remained the same and the predicted curves were similar to the observed ones. For vetiver, the simulation was not as effective, probably due to the effects of transport properties on the process.
Energy Procedia, 2012
In this work essential oil was extracted from Algerian Rosemary leaves by the supercritical CO 2 extraction. The effects of the key parameters such as pressure and temperature on the yield of extraction were examined. The obtained yield were in the range of 0.95-3.52 g of dry oil / g of rosemary, and the best value was obtained at a pressure of 22 MPa and temperature of 40°C. The model of shrinking-core was used to analyse the experimental results of the extraction, this model contains one adjustable parameter, effective diffusivity De, the experimental results were successfully fitted.
Industrial & Engineering Chemistry Research, 1999
Supercritical CO 2 extraction of fennel seeds has been performed in two steps; the first step was performed at 90 bar and 50°C to obtain the selective extraction of essential oil. The second one was performed at 200 bar and 40°C and allowed the extraction of vegetable oil. The experiments were performed using the fractional separation of the extracts using three different CO 2 flow rates (0.5, 1.0, and 1.5 kg/h). On the basis of the extraction results and of the analysis of scanning electron microscopy (SEM) images of the vegetable matter, mathematical models of the two extraction processes have been proposed. The extraction of fennel vegetable oil has been modeled using a model based on differential mass balances and on the concept of broken and intact cells as evidenced by SEM. Only one adjustable parameter has been used: the internal mass-transfer coefficient k t. A fairly good fitting of the experimental data was obtained by setting k t) 8 × 10-8 m/s. The fennel essential oil extraction process was modeled as desorption from the vegetable matter plus a small mass-transfer resistance. The same internal mass-transfer coefficient value used for vegetable oil extraction allowed a fairly good fitting of the essential oil extraction data.
Mathematical modelling and simulation of pennyroyal essential oil supercritical extraction
Chemical Engineering Science, 2000
Pennyroyal essential oil was isolated by supercritical #uid extraction and fractional separation. Extractions were performed at three di!erent mean particle sizes (0.3, 0.5 and 0.7 mm) and three CO #ow rates (0.31, 0.43, and 0.62 g/s) and at p"100 bar and ¹"323 K. Essential oil yield was determined as a function of time. Yield data and physical considerations based on the botanical structure of pennyroyal leaves were used to screen the possible mass transfer mechanisms. Two mathematical models were constructed, based on the numerical integration of di!erential mass balances written along the extraction bed. They take into account the desorption of essential oil located near the leaf surface and the mass transfer resistance to the extraction of the part of essential oil contained in the internal part of the vegetable structure. Axial dispersion was also taken into account. Yield curves for all particle sizes and CO #ow rates were fairly well "tted using the internal mass transfer coe$cient K G as the only adjustable parameter of the model. The best "t value was K G "1.4;10\ m/s. Once the model was validated on the experimental data, simulations were performed for (a) di!erent partitions of essential oil between the surface and internal cells of leaves, and (b) a larger range of CO #ow rates. Simulation results can be applied to other vegetable species and to determine the performance of this process on a larger scale plant.