Mathematical modelling and simulation of pennyroyal essential oil supercritical extraction (original) (raw)
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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.
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.
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.
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.
Mathematical modelling of essential oil SFE on the micro-scale—Classification of plant material
The Journal of Supercritical Fluids, 2008
This article reports the achievements of the micro-scale (secretory-structure-scale) mathematical modelling of essential oil isolation by supercritical carbon dioxide. Some new experimental and modelling results are presented. The improved model for the supercritical fluid extraction from the glandular trichomes (peltate glands) is introduced. According to the behavior of plant secretory structures during the extraction as well as according to the modelling results, plant material was classified according to the dominant resistance to mass transfer during the extraction process. External mass transfer was the rate limiting step in the extraction from plants with secretory ducts and secretory cavities of citrus family. In the case of extraction from secretory cells, internal diffusion was the rate limiting step. In the extraction from glandular trichomes, external mass transfer, as well as diffusion through the gland membrane influenced the process.
The Journal of Supercritical Fluids, 2014
Bed geometry plays an important role in supercritical fluid extraction kinetics. Thus, the objective of this study was to compare the overall extraction curves (OEC's) of rosemary compounds obtained in two beds of 1 L each with different geometries (in terms of height to bed (H B ) diameter (D B ) ratios, H B /D B ). A scale-up study was carried out maintaining the solvent mass to feed mass (S/F) ratio equal for both beds. Other process variables, such as bed porosity, apparent and true densities of the raw material, particle average size, temperature, pressure and time of extraction, were also maintained constant. The kinetic parameters were obtained by fitting the OEC to a spline model. The results revealed differences of mass transfer rates, mass ratios of solute in the fluid phase and yields of extract in the constant extraction rate period. The evaluation of the OEC's and kinetic parameters indicated that the bed with lower H B /D B ratio (H B /D B = 2.7) was more favorable for obtaining rosemary extract. The kinetics of extraction of oxygenated monoterpenes (i.e., 1,8-cineole and camphor) and phenolic diterpenes (i.e., carnosic acid) were also different for both bed geometries. These behaviors suggest that the bed geometry presents a pronounced influence in the mass transport properties in supercritical media. Thus, in spite of the scale-up criterion be successful for several botanic matrices such as clove buds, sugarcane residue and grape seeds residue, the criterion applied in this study (maintaining a constant S/F ratio for a given time of extraction) was not suitable for this raw material.
Mathematical modelling of supercritical CO2 extraction of volatile oils from aromatic plants
Chemical Engineering Science, 2010
The modelling of the experimental data of the extraction of the volatile oil from six aromatic plants (coriander, fennel, savoury, winter savoury, cotton lavender and thyme) was performed using five mathematical models, based on differential mass balances. In all cases the extraction was internal diffusion controlled and the internal mass transfer coefficient (k s ) have been found to change with pressure, temperature and particle size. For fennel, savoury and cotton lavender, the external mass transfer and the equilibrium phase also influenced the second extraction period, since k s changed with the tested flow rates.
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
The Journal of Supercritical Fluids, 2005
The fixed bed extraction of marigold (Calendula officinalis) oleoresin with liquid and supercritical carbon dioxide was investigated. The operating conditions studied were: pressures ranging from 12 to 20 MPa and temperatures from 293 to 313 K, indicating solvent densities ranging from 666 to 938 kg CO 2 /m 3 , and solvent flow rate varying from 1.3 × 10 −5 to 5.0 × 10 −5 kg CO 2 /s. The results show an increase in the extraction rate, observed through the overall extraction curves (OEC), with increasing pressure. The experimental data were correlated using three models based on differential mass balance equations: (1) the Sovová model; (2) the logistic model presented by Martínez et al. and (3) the desorption model proposed by Tan and Liou; and two models based on heat transfer analogy: (4) the simple single plate model (SSP), presented by Gaspar et al. and (5) the diffusion model, proposed by Crank and presented by Reverchon. All models fitted well the experimental data and the lowest deviation between experimental and correlated data was obtained with the logistic model, for all the experimental conditions evaluated.
Computers & Chemical Engineering, 2013
This article deals with mathematical tools used for solving equations of the improved mathematical model on the micro-scale for the process of supercritical fluid extraction of essential oils from glandular trichomes. Glandular trichomes are secretory structures of Lamiaceae plant family and as such represent the sites of essential oil synthesis and storage. It was previously noticed that during the extraction with carbon dioxide these secretory structures undergo cracking due to the solvent dissolving into the essential oil phase. In this study, the process of extraction is thoroughly analysed and mathematically presented on the fixed bed scale as well as on the single trichome scale. The finite differences method was applied for solving differential equations of the model. This included dividing the extractor vessel into twenty spatial, and extraction time into ten thousand time increments. Cracking time distribution of glandular trichomes in the form of Gamma distribution was incorporated in each of the twenty spatial increments. The model was applied to simulate experimental results of supercritical extraction from several species of the Lamiaceae family. The deviation of the model results from the experimental data was 9.6-35.7% lower for the improved model than for the model without the cracking time distribution function.