MODELING OF SPEARMINT OIL EXTRACTION IN A PACKED BED USING SC-CO2

The packed bed extraction of spearmint oil using supercritical carbon dioxide was studied by a two-phase mass transfer model on the basis of desorption and diffusion. Unsteady-state mass balance for solute in supercritical and in solid phases led to two partial differential equations that were solved numerically using a linear equilibrium relationship. The model has four parameters, axial dispersion, mass transfer, and diffusion and desorption coefficients. Diffusion and desorption coefficients were used as the model tuning parameters and the others were predicted applying existing experimental correlations. The tuning parameters were calculated by the fitting error between 5 and 15% by the genetic algorithm method. In addition, this model was compared with a model that did not account for the desorption rate, according to the model suggested by Goodarznia and Eikani (G&E). Moreover, the effects of operational parameters such as pressures, temperatures, CO₂ flow rates, and mean particle sizes on the extraction yield were evaluated. In order to obtain experimental data for spearmint oil, a facility was designed and constructed to conduct the experimental part of this study. The two models were also applied to the literature's experimental data for rosemary leaves, grape seeds, peanuts, and tomato seeds. Comparison of the results of the proposed model with results from the G&E model indicated that the proposed model had better predictability. Also, good agreement of the proposed model results and the experimental data confirmed the basic hypothesis of the model and the importance of the desorption rate.     

Experimental optimization and mathematical modeling of supercritical carbon dioxide extraction of essential oil from Pogostemon cablin

The supercritical carbon dioxide extraction was applied to obtain essential oil from Pogostemon cablin in this work. Effect of extraction parameters including temperature, pressure, extraction time and particle size on extraction yield was investigated, and the response surface methodology with a Box-Behnken Design was used to achieve the optimized extraction conditions. The maximum yield of essential oil was 2.4356% under the conditions of extraction temperature 47℃, pressure 24.5 MPa and extraction time 119 min. Moreover, based on the Brunauer-Emmett-Teller theory of adsorption, a mathematical modeling was performed to correlate the measured data. The model shows a function relationship between extraction yield and time by a simple equation with three significantly adjustable parameters. These model parameters have been optimized through simulated annealing algorithm. The predicted data from the mathematical model show a good agreement with the experimental data of the different extraction parameters.     

Optimization of supercritical carbon dioxide extraction of Passiflora seed oil

This study investigates extraction of Passiflora seed oil by using supercritical carbon dioxide. Artificial neural network (ANN) and response surface methodology (RSM) were applied for modeling and the prediction of the oil extraction yield. Moreover, process optimization were carried out by using both methods to predict the best operating conditions, which resulted in the maximum extraction yield of the Passiflora seed oil. The maximum extraction yield of Passiflora seed oil was estimated by ANN to be 26.55% under the operational conditions of temperature 56.5 °C, pressure 23.3 MPa, and the extraction time 3.72 h; whereas the optimum oil extraction yield was 25.76% applying the operational circumstances of temperature 55.9 °C, pressure 25.8 MPa, and the extraction time 3.95 h by RSM method. In addition, mean-squared-error (MSE) and relative error methods were utilized to compare the predicted values of the oil extraction yield obtained from both models with the experimental data. The results of the comparison reveal the superiority of ANN model compared to RSM model.     

植物种子油超临界流体萃取研究进展

论述了植物种子油超临界流体萃取技术的重要性和最新发展 ,重点就植物种子油萃取研究领域内的实验研究、数学建模以及过程控制和模拟优化技术进行了评述。介绍了人工神经网络技术在超临界流体萃取过程动力学研究中的应用     

Extraction from a polydisperse granular layer of milled oilseeds with supercritical carbon dioxide

A mathematical model of the supercritical fluid extraction of oil from a polydisperse granular layer of milled oilseeds is proposed. An experiment on the extraction of a polydisperse layer of white lupin seeds with different realizations of the size distribution function of the grains was carried out. The results of the laboratory experiment were used for the adaptation of the mathematical model; a fair agreement between the calculated and experimental curves of the oil yield was achieved.     

Comparison of different extraction methods for the extraction of major bioactive flavonoid compounds from spearmint (Mentha spicata L.) leaves

Different bioactive flavonoid compounds including catechin, epicatechin, rutin, myricetin, luteolin, apigenin and naringenin were obtained from spearmint (Mentha spicata L.) leaves by using conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO₂) extraction at different extraction schemes and parameters. The effect of different parameters such as temperature (40, 50 and 60 °C), pressure (100, 200 and 300 bar) and dynamic extraction time (30, 60 and 90 min) on the supercritical carbon dioxide (SC-CO₂) extraction of spearmint flavonoids was investigated using full factorial arrangement in a completely randomized design (CRD). The extracts of spearmint leaves obtained by CSE and optimal SC-CO₂ extraction conditions were further analyzed by high performance liquid chromatography (HPLC) to identify and quantify major bioactive flavonoid compounds profile. Comparable results were obtained by optimum SC-CO₂ extraction condition (60 °C, 200 bar, 60 min) and 70% ethanol soxhlet extraction. As revealed by the results, soxhlet extraction had a higher crude extract yield (257.67 mg/g) comparing to the SC-CO₂ extraction (60.57 mg/g). Supercritical carbon dioxide extract (optimum condition) was found to have more main flavonoid compounds (seven bioactive flavonoids) with high concentration comparing to the 70% ethanol soxhlet extraction (five bioactive flavonoids). Therefore, SC-CO₂ extraction is considered as an alternative process compared to the CSE for obtaining the bioactive flavonoid compounds with high concentration from spearmint leaves.     

Recovery of γ-oryzanol from rice bran oil byproduct using supercritical fluid extraction

The residue of fatty acids distillation from rice bran oil soapstock (RFAD-RBOS) is a byproduct from rice bran oil industry. It contains a large amount of γ-oryzanol, which is a valuable antioxidant. The main objective of this work was to investigate the recovery of γ-oryzanol from the RFAD-RBOS using supercritical fluid extraction (SFE). The Soxhlet technique was conducted in order to compare results with SFE. The influence of process parameters over SFE was evaluated in terms of global yield, γ-oryzanol content, γ-oryzanol recovery rate, and fatty acids composition. The mathematical modeling of SFE overall extraction curve (OEC) was also investigated. The condition of 30 MPa/303 K presented the maximum global yield (39 ± 1%, w/w), maximum γ-oryzanol recovery rate (31.3%, w/w), relatively high γ-oryzanol content (3.2%, w/w), and significant presence of monounsaturated and polyunsaturated fatty acids. The logistic model presented the best fit to experimental OEC.     

Process optimisation in sunflower oil extraction by supercritical CO2

A continuous process for the extraction of sunflower oil using supercritical CO₂, featuring multiple extractors, one oil separator and three cascaded CO₂ recovery vessels operating at different pressures, was devised and studied. For every single equipment of the plant making up the process a mathematical model was built. Experimental tests—consisting in measurements of oil solubility in supercritical CO₂—were carried out in a laboratory-scale apparatus to characterise the behaviour of sunflower oil in the separation from the supercritical fluid. The mathematical model of the whole process was coded in the commercial gPROMS process modelling environment where both its simulation and optimisation—this latter assuming the overall oil production cost as the objective function—were carried out. The process- and economics-related results are discussed and compared with those obtained with traditional and cold-pressing extraction.     

CO2 supercritical fluid extraction of Jordanian oil shale utilizing different co-solvents

In this study, extracting shale oil from Jordanian oil shale using supercritical fluid extraction has been investigated. Experimental data indicates that by using supercritical extraction with carbon dioxide, using co-solvents can be viable. A relatively high yield can be obtained at relatively moderate pressure. At the highest temperature and pressure of 450 °C and 3200 psi, respectively, and with hexane as a co-solvent, the highest yield obtained was 100 kg/ton of oil shale, which was at the highest temperature and pressure of 450 °C and 3200 psi, respectively, and with hexane as a co-solvent. Increasing both the operating pressure and temperature increases the oil yield. In the supercritical state, carbon dioxide along with other co-solvents, such as hexane and acetone, interact with the kerogen leading to the dissolution of fragments due to an increase in solubility and mass transfer.Increasing the particle size of oil shale for extraction decreases the oil yield. Most of the extracted oil obtained is saturated hydrocarbons, olefinic and a portion of aromatic hydrocarbons. As the extraction temperature increases, the production of low-molecular weight compounds increases.     

Mathematical modeling and genetic algorithm optimization of clove oil extraction with supercritical carbon dioxide

In the present study, a mathematical modeling for extraction of oil from clove buds using supercritical carbon dioxide was performed. Mass transfer is based on local equilibrium between solvent and solid. The model was solved numerically, and model estimation was validated using experimental data. For optimization, the clove oil equilibrium constant between solid and supercritical phase was determined by a theoretical method using fugacity concept, consequently the genetic algorithm for obtaining optimal operational conditions was used. The optimal conditions which obtained the highest amount of clove oil were pressure of 10 MPa and temperature of 304.2 K.     

紫苏油在超临界CO_2中溶解度的神经网络模型建立

测定了紫苏油在超临界CO2 (SC CO2 )中的溶解度 ,利用误差逆传播 (BP)神经网络对溶解度数据进行了拟合。通过对萃取参数与溶解度的关系进行训练 ,实现网络结构的优化 ,建立了紫苏油在SC CO2 溶解度的网络模型 ,并将该模型用于一定范围内未知萃取参数下溶解度的预测 ,得到了较高的预测精度。结果表明 ,该方法可作为预测物质在SC CO2 溶解度的一种有效手段。     

Near-critical carbon dioxide extraction of khoa (Satureja boliviana Benth Briq) using ethanol as a co-solvent: Experiment and modeling

In this work the volatile oil from khoa was extracted using pressurized CO₂ with and without ethanol as co-solvent. Kinetic experiments were performed at pressures of 6.5 and 7 MPa and temperatures of 294.15 K. The composition of the volatile oil was determined using gas chromatography. The volatile oil was formed predominantly by cymene, 1-8 cineole, isomenthone, pulegone, thymol and caryophyllene. Consequently, we present a mathematical modeling study of the extraction of essential oil from khoa. The overall extraction curves (OECs) obtained for khoa oil were modeled considering the mass transfer based on local equilibrium between solvent and a solid. The influence of pressure and co-solvent on the extraction kinetics was evaluated using a mathematical modeling. The model was solved numerically and validated with experimental data. A novel method for calculating the initial mass fraction of khoa-extract is proposed; data of the proposed model are in excellent agreement with the experimental data. Furthermore, the influence of fluid flow rate and particle size has been studied on the extraction efficiency. Finally, a methodology has been established to estimate extraction yield curves in large scale using the data obtained in small-scale experiments.     

Cetirizine solubility in supercritical CO2 at different pressures and temperatures

A simple static technique was used to obtain the solubility of cetirizine in supercritical carbon dioxide. The solubility measurements were performed at temperatures and pressures ranging from 308.15 to 338.15 K and 160 to 400 bar, respectively; resulting in mole fractions in the 1.05 × 10⁻⁵ to 4.92 × 10⁻³ range. The Chrastil, Bartle, Kumar & Johnston and the Mendez-Santiago and Teja (MST) models were used to correlate the experimental data. The calculated solubilities showed good agreement with the experimental data in the temperature and pressure ranges studied.     

Supercritical fluid extraction from Syzygium aromaticum buds: Phase equilibrium,mathematical modeling and antimicrobial activity

Clove essential oil is an important product to food industry because it presents a powerful antioxidant and antimicrobial potential enabling its use for the substitution of synthetic commercial products for food preservation. The objective of this paper is to study the extraction kinetics for predicting operational condition to obtain Syzygium aromaticum essential oil using CO₂ as solvent by means of the introduction of thermodynamic approach into the mathematical modeling of the process. Extractions were performed at 9000 kPa/313.15 K, 10,000 kPa/313.15 K, 9000 kPa/323.15 K, and 10,000 kPa/323.15 K and the essential oil yields obtained were 14.17%, 12.32%, 13.11%, and 14.02%, respectively. To calculate the extract solubility in CO₂ supercritical, the Peng–Robinson EoS coupled with three mixing rules (van der Waals 1, van der Waals 2 and Mathias–Klotz–Prausnitz) was used and a mass transfer model was employed to represent the relationship yield versus extraction time. The mathematical modeling of the process using the calculated solubility presented high concordance with experimental data. The volatile extracts were analyzed by GC/MS and the major compounds were eugenol and β-caryophyllene. Also, minimum inhibitory concentration (MIC) of supercritical extracts was determined with respect to Escherichia coli, Staphylococcus aureus and Enterococcus faecalis by microdilution method. All samples inhibited the bacterial growth, being the extract obtained at 313.15 K/9000 kPa the most effective.     

Supercritical Carbon Dioxide Extraction and Characterization of Argentinean Chia Seed Oil

Extraction of chia seed oil was performed with supercritical carbon dioxide (SC-CO₂). To investigate the effects of pressure and temperature on the oil solubility and yield, two isobaric (250 and 450 bar) and two isothermal (40 and 60 °C) extraction conditions were selected. The global extraction yield of chia oil increased with pressure enhancement, but temperature had a little influence on it. The maximum oil recovery using SC-CO₂ at a mass flow rate of 8 kg/h was 97%, which was obtained at 60 °C, 450 bar for a 138-min extraction. The results showed that solubility changed from 4.8 g oil/kg CO₂ at 60 °C–250 bar to 28.8 g oil/kg CO₂ at 60 °C–450 bar. The final extract obtained by SC-CO₂ under different conditions and Soxhlet extraction contained mainly α-linolenic (64.9–65.6%) and linoleic (19.8–20.3%) acids. SC-CO₂ extraction is an interesting alternative methodology because it is possible to achieve a chia oil yield close to that obtained by conventional extraction with a similar fatty acid composition using an environmentally friendly process.     

川芎油在超临界二氧化碳中溶解度的测定与关联

Extraction of the Ligusticum Chuanxiong oil with supercritical CO2 （SC-CO2） was investigated at the temperatures ranging from 55℃ to 70℃ and pressure from 25 MPa to 35 MPa. The mass of Ligusticum Chuanxiong oil extracted increased with pressure at constant temperature. The initial slope of the extraction was considered as the solubility of oil in SC-CO2. Chrastil equation was used to correlate the solubility data of Ligusticum Chuanxiong oil. An improved Chrastil equation was also presented and was employed to correlate the solubility data, The correlation results show that the values of the average absolute relative deviation are 5.94% and 3.33% respectively, indicating the improved version has better correlation accuracy than that of Chrastil equation.     

Exploiting microalgae as a source of essential fatty acids by supercritical fluid extraction of lipids: Comparison between Scenedesmus obliquus,Chlorella protothecoides and Nannochloropsis salina

Supercritical CO₂ extraction from microalgae is applied with the aim of obtaining an oil rich in α-linolenic (ALA) essential fatty acid and with a low ω6:ω3 ratio. The maximum extraction yield is obtained at 60 °C and 30 MPa with 0.4 kg/h of CO₂ and 5% of co-solvent (ethanol). When the effect of pressure, temperature and density on the supercritical extraction yield and solubility are studied, the thermodynamic cross-over is found at a pressure close to 30 MPa, while the extraction cross-over occurs at around 25 MPa. The experimental solubility data are correlated by literature empirical models. Mathematical models developed by Sovová are applied to describe the experimental extraction curves. Soxhlet extraction of lipids is also carried out, obtaining a similar fatty acids profile but proving to be less selective than SCCO₂ method. Among the three species of microalgae examined, results show that Scenedesmus obliquus oil is richer in ω-3 fatty acids and ALA than Chlorella protothecoides and Nannochloropsis salina lipids. The effect of the extraction parameters on ALA content and the fatty acid profile is also analysed, concluding that the ω-3 percentage is favoured by lower temperatures, lower pressures and shorter extraction times.