Supercritical Fluid Extraction Process Research Articles

Identification of β‐sitosterol, stigmasterol and ergosterin in A. roxburghii using supercritical fluid extraction followed by liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry

beta-Sitosterol and stigmasterol are the most common phytosterols in traditional Chinese medicine. They have been proved to have many important bioactivities. To the best of our knowledge, this is the first report that beta-sitosterol, stigmasterol and ergosterol coexisting in A. roxburghii herbs can be simultaneously extracted by a supercritical fluid extraction (SFE) procedure; then a simple high-performance liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry (HPLC/APCI/MS) method was developed for simultaneous identification and determination of these three compounds. The ion trap MS/MS detector was equipped with an atmospheric pressure chemical ionization source operating in the positive ion mode, APCI(+). The linear responses were obtained in the concentration range of 0.50-150 microg/mL (r = 0.9999) for ergosterol, 5-400 microg/mL (r = 0.9999) for stigmasterol, and 10-2000 microg/mL (r = 0.9998) for beta-sitosterol. An orthogonal L(9) (3(3)) test design was employed for optimization of the SFE process. Under the optimized conditions, i.e. pressure of 25 mPa, temperature of 45 degrees C and ethanol as modifier, the concentrations of sterols in the extract were found to be 2.89% (g/g) for beta-sitosterol, 3.56% (g/g) for stigmasterol and 2.96% (g/g) for ergosterin. The SFE method was also compared with a previously developed Soxhlet extraction. The SFE method produced higher yields of sterols than that of the Soxhlet extraction. The proposed method has been successfully used for identification and quantitation of beta-sitosterol, stigmasterol and ergosterin in a real A. roxburghii sample.

Static mixers as heat exchangers in supercritical fluid extraction processes

The performance of a Kenics static mixer as a heat-transfer device for supercritical carbon dioxide (CO 2) flow is studied and compared with conventional tube-in-tube heat exchangers. Measurements were carried out at pressures ranging from 8 to 21 MPa, temperatures from 283 to 323 K, and mass flowrates from 2 to 15 kg/h. The corresponding Reynolds and Prandtl numbers, at bulk conditions, ranged between 10 3 and 2 × 10 4 and between 2 and 7, respectively. The temperature increase experienced by the supercritical CO 2 stream varied between 10 and 35 K. The heat fluxes obtained with the static mixer are one order of magnitude higher than the ones observed with a tube-in-tube heat exchanger for the same set of operating conditions. The heat-transfer enhancement is caused by the cross-sectional mixing of the fluid and to a lesser extent by conduction across the metallic mixing elements. Heat-transfer is also affected by temperature-induced variation of physical properties, especially in the pseudocritical region of the fluid. From the experimental data, a correlation was developed for convective heat-transfer to supercritical CO 2 in terms of the Nusselt number.

Comparison of techniques for the extraction of the hypotensive drugs geniposidic acid and geniposide from Eucommia ulmoides

The extraction of geniposidic acid and geniposide from Eucommia ulmoides was carried out by Soxhlet extraction, enzyme-assisted aqueous extraction, semi-bionic extraction and supercritical fluid extraction techniques and the extracts were analyzed by high performance liquid chromatography. The results showed that the best methods for extraction of geniposidic acid and geniposide are enzyme-assisted aqueous extraction and semi-bionic extraction. Compared with various extraction methods, the semi-bionic extraction was more efficient, yielding the highest amount of geniposidic acid and geniposide. In semi-bionic extraction, no organic solvent was used. Semi-bionic extraction was performed at the same pH as that of the human body. The results indicated that semi-bionic extraction was the best method for large-scale efficient extraction of geniposidic acid and geniposide from plant materials. The supercritical fluid extraction process required more time than the other methods, and gave the lowest yields of geniposidic acid and geniposide.

Dynamic model of a supercritical fluid extraction plant

AbstractA dynamic model of a supercritical fluid extraction (SFE) process was developed and applied to the fractionation of the binary mixture squalene/methyl oleate by supercritical carbon dioxide. The model combines a mathematical model for each main piece of equipment of the SFE process, namely, the countercurrent packed extraction column, the separation column for oil recovery and solvent regeneration, the heat exchanger for heating fresh CO2, and the make‐up of solvent in the process plant. Experimental tests were performed in a pilot‐plant SFE apparatus where perturbations on prespecified operating parameters were induced and their effect on main process variables determined. A good agreement was obtained between experimental and predicted results. In addition, the dynamic model of the packed extraction column was applied to other SFE case studies where sufficient experimental data is available. The dynamic model was found to correctly predict the outlet streams composition profiles of all the case studies. © 2007 American Institute of Chemical Engineers AIChE J, 2007

Comparative Evaluation of SFE and Steam Distillation Methods on the Yield and Composition of Essential Oil Extracted from Spearmint (Mentha spicata)

A supercritical fluid extraction (SFE) process was optimized to obtain high quality mint oil. The effect of oven and freeze drying techniques on the quality of mint oil was investigated. The flavor principles in the SFE extract were compared with those obtained by a conventional steam distillation method. Then highest extraction yield was obtained at SFE conditions (50°C and 350 bar), however, high quality oil was obtained at 30°C and 150 bar. The compositional quality of SFE extract was found to be superior as compared to that of a steam distillation process. The extraction yield and compositional quality of oil from mint samples obtained from different regions of UAE and other countries were reported.

Stabilization of all-trans-lycopene from tomato by encapsulation using cyclodextrins

The stabilization of all-trans-lycopene from tomato by encapsulation using α-, β- and γ-cyclodextrins (CDs) was evaluated. To that end, two different encapsulation methods were comparatively studied: a conventional method and a supercritical fluid extraction (SFE) process. An optimization procedure considering distinct molar ratios of CD/lycopene (1/0.0026, 1/0.005 and 1/0.05) as well as the type of cyclodextrin to be used was accomplished. The encapsulation was determined by using micro-Raman spectroscopy. All- trans-lycopene employed was obtained by SFE with a purity around 90–95%. As a result, a molar ratio CD/lycopene of 1/0.0026 was selected as it provided the best complexation yields (93.8%) whilst β-CD seemed to be the most favorable to be used to stabilize lycopene. A comparison of the two methods studied reflected higher encapsulation yields from the conventional method. However, the supercritical fluid approach offers numerous advantages such as the possibility of performing the extraction, fractionation and encapsulation of lycopene from tomato in one step, shortening notably the overall procedure time and minimizing the sample handling.

Effects of supercritical fluid extraction on Curcuma longa L. and Zingiber officinale R. starches

Ginger and turmeric tubers have approximately 45 and 40% of starch, respectively. These starches were analyzed before and after ginger and turmeric were subjected to supercritical fluid extraction to obtain oleoresin and essential oil. The starches were isolated and analyzed with respect to purity, amylose/amylopectin content, X-ray pattern, viscosity, swelling factor, granule morphology by scanning electron microscopy, gelatinization temperature by differential scanning calorimetry and turbidity. Supercritical fluid extraction process did not alter the starchy matrix showing small physical rearrangement of the starch molecules; this effect was more intense in the ginger starch, as observed by X-ray diffraction. The ginger starch became less resistant, in other words, there was a starchy structure relaxing after supercritical fluid extraction, evidenced by the lower setback value in the gelatinization process and nonetheless, it did not alter the granule morphology as observed by microscopy. This study reveals similar characteristics of these starches with commercial starches, indicating their potential for industrial applications.

Supercritical fluid extraction of oil from microalgaSpirulina (arthrospira) platensis

For the extraction of oil from microalgae, which are recognised as an important renewable source of bioactive lipids, supercritical CO 2 is regarded with interest being safer than hexane and offering a negligible environmental impact, short extraction time and petroleum-free final product. A mathematical model, able to describe the kinetics of a supercritical fluid extraction (SFE) process, was applied to the recovery of oil from the cyanobacterium Spirulina (Arthrospira) platensis, characterised by a particularly high content in γ-linolenic acid (C18:3ω-6). In this paper, we examine the kinetics of the SFE and the effect of operating conditions on extraction yield and fatty acid composition of lipid extracts.

Extraction of fat from pigskin with supercritical carbon dioxide

Abstracts A supercritical fluid extraction process for reducing the fat content of pigskin is presented in this work. Carbon dioxide has been used as supercritical solvent for fat extraction. Efficiencies close to 100% were reached. The influence of process parameters – such as extraction temperature, pressure and time and solvent ratio – on the extraction yield was studied. The influence of other variables such as initial fat and water content of the pigskin was also considered. The results showed that when using pigskin sheets, for non-interrupted extractions, there was an extraction yield limit, of around 60%, that could not be overcame even using an extraction pressure of 65 MPa. Some experiments that were interrupted for sampling of the pigskin showed that there was a positive influence of the intermediate depressurizations of the extractor on the extraction yield and, in this case, values close to 100% could be reached. The analysis of the results gave rise to the conclusion that the external mass transfer resistance could be easily eliminated by increasing the solvent flow rate through the extractor. The internal mass transfer resulted to be the main resistance controlling the rate of the process, although, in the very first part of the extraction, it was the solubility that imposed the limit to the process rate. A steady-state approximation of the extraction from solids was used to model the experimental data and to obtain the total mass transfer coefficient that would allow the scale up of the process.

Heavy metal removal from contaminated sludge for land application: A review

In recent years, various methods for heavy metal removal from sewage sludge have been extensively studied in order to minimize the prospective health risks of sludge during land application. In this paper, a comparative review and critical analysis of the application of chemical extraction, bioleaching, electroreclamation, and supercritical fluid extraction (SFE), in removing heavy metals from contaminated sludges is presented. Moreover, speciation studies, which can indicate ease of leachability of the different forms of heavy metals in sludge, are also presented. Experimental studies revealed a broad range in metal extraction efficiencies of the different extraction technologies. Acid treatment seemed to effectively remove Cd, attaining as much as 100% removal for some studies, as compared to bioleaching. SFE also gave higher removal efficiency than bioleaching. Cr, Pb and Ni seemed to be also effectively removed by the acid treatment. For the removal of Cu, Mn and Zn, the bioleaching process seemed to be appropriate with maximum removal efficiencies of 91%, 93% and 96% for the three metals, respectively, and as high as 64% minimum removal efficiency for Zn. The SFE process also gave good results for Cu, Mn and Zn removal. Electroreclamation exhibited better removal efficiency for Mn, but is still inferior to acid treatment and bioleaching processes. For chemical extraction, because of the adverse impacts that can result from the use of inorganic acids and complexing agents, interest can be directed more toward utilizing organic acids as extracting agents because of their biodegradability and capability to remove metals at mildly acidic condition, hence requiring less acid. The bioleaching process, although it seems to give a higher yield of metal extraction with lower chemical cost than chemical extraction, may be limited by the inability of the system to cope with the natural environmental conditions, requires strict monitoring of aeration rate and temperature and has applicability to only low sludge solids concentration. A full-scale study would be useful to better assess the efficiency of the process. The electroreclamation technology is limited by its relatively higher energy consumption and limited applicability to sludge. The SFE method, on the other hand, is limited by the complexity of the process and the cost of ligands suitable for effective metal extraction. Both of these technologies are still in their early stage of application and hence there is a need for further basic and applied studies. Finally, the common advantage for almost all treatment technologies studied is that the extraction efficiencies for some metals are high enough to remove metals from sludge to levels suitable for land application.

Microstructural effects on internal mass transfer of lipids in prepressed and flaked vegetable substrates

Predictive models that describe supercritical fluid extraction (SCFE) processes would be welcomed to support its industrial application, particularly for the supercritical carbon dioxide (SC CO 2) extraction of vegetable oil from seeds subjected to common high-shear pretreatments. This work explores the application of microstructure-extractability relationships for modeling the SCFE of lipids from vegetable substrates. We measured the extraction kinetics of prepressed rapeseeds, olive husks, and flaked rosehip seeds, with SC CO 2 at 313 K and 30 MPa, and simulated the extractions using a shrinking-core model. Model parameters included the oil solubility and film mass transfer coefficient from literature correlations, and an effective diffusivity ( D e) inside the porous particles. We determined that D e could be calculated as D 12 × F, where D 12 is the diffusivity of oil in CO 2, and F is a microstructural correction factor, estimated as the ratio between the final porosity ( ɛ p, from Hg porosimetry) and pore-network tortuosity ( τ, from fractal-texture analysis of binary light-microscopy images) of the substrates. Simulations adjusted the experimental data reasonably well (5.4% < mean percent error < 15%). Additionally, best-fit estimates of D e were obtained for literature data on SC CO 2 extraction of lipids from prepressed and flaked seeds. Resulting values of F did not depend on particle size and spanned a narrow range – one order of magnitude (0.030–0.29) – as it would be expected when comparing similar systems. Although further work will be required to refine the relationship between τ and fractal parameters, or between τ and the hysteresis of Hg infiltration, this work demonstrates that is possible to develop predictive models for SCFE of solid substrates subjected to high-shear pretreatments.

Remediation of flare pit soils using supercritical fluid extraction

Supercritical fluid extraction (SFE) is a promising remediation technology for contaminated soils. This work investigates the use of SFE to remove petroleum hydrocarbons (PHCs) from flare pit soils. Extractions were performed on two flare pit soils at pressures ranging from 11.0 to 24.1 MPa and at temperatures ranging from 40 to 80 °C in an attempt to identify the best extraction conditions and to understand the effects of pressure, temperature, supercritical fluid flow rate, soil type, and extraction time on the extraction efficiency. For the conditions studied, the efficiency of the SFE process appeared to be solvent-density dependent. Conditions of 24.1 MPa and 40 °C (highest supercritical fluid density) yielded the highest extraction efficiency for both soils (89% for the sand and 80% for the loam). An increase in temperature at a fixed pressure led to a decrease in the extraction efficiency while an increase in pressure at a fixed temperature led to an increase in the extraction efficiency. The treated soils appeared to be drier, grainy, and lighter coloured than the soil prior to extraction.Key words: supercritical fluid extraction (SFE), supercritical carbon dioxide, flare pit soils, contaminated soil, soil remediation, biorecalcitrant petroleum hydrocarbons.

Chemical Composition of Juniperus communis L. Fruits Supercritical CO2 Extracts: Dependence on Pressure and Extraction Time

Ground fruits of the common juniper (Juniperus communis L.), with a particle size range from 0.250-0.400 mm, forming a bed of around 20.00 +/- 0.05 g, were extracted with supercritical CO(2) at pressures of 80, 90, and 100 bars and at a temperature of 40 degrees C. The total amount of extractable substances or global yield (mass of extract/mass of raw material) for the supercritical fluid extraction process varied from 0.65 to 4.00% (wt). At each investigated pressure, supercritical CO(2) extract fractions collected in successive time intervals over the course of the extraction were analyzed by capillary gas chromatography, using flame ionization (GC-FID) and mass spectrometric detection (GC-MS). More than 200 constituents were detected in the extracts, and the contents of 50 compounds were reported in the work. Dependence of the percentage yields of monoterpene, sesquiterpene, oxygenated monoterpene, and oxygenated sesquiterpene hydrocarbon groups on the extraction time was investigated, and conditions that favored the yielding of each terpene groups were emphasized. At all pressures, monoterpene hydrocarbons were almost completely extracted from the berries in the first 0.6 h. It was possible to extract oxygenated monoterpenes at 100 bar in 0.5 h and at 90 bar in 1.2 h. Contrary to that, during an extraction period of 4 h at 80 bar, it was possible to extract only 75% of the maximum yielded value of oxygenated monoterpene at 100 bar. Intensive extraction of sesquiterpenes could be by no means avoided at any pressure, but at the beginning of the process (the first 0.5 h) at 80 bar, they were extracted about 8 and 3 times slower than at 100 and 90 bar, respectively. Oxygenated sesquiterpenes were yielded at fast, constant extraction rates at 100 and 90 bar in 1.2 and 3 h, respectively. This initial fast extraction period was consequently followed by much slower extraction of oxygenated sesquiterpenes.

Stoichiometric Relation for Extraction of Uranium from UO2 Powder using TBP Complex with HNO3 and H2O in Supercritical CO2

The stoichiometry of UO2 dissolution with a tri-n-butylphosphate (TBP) complex with HNO3 and H2O was experimentally determined in supercritical carbon dioxide (SF-CO2) at 25 MPa, 323 K to estimate the required amount of the complex for a process design calculation. The molecular ratio of TBP:HNO3:H2O was determined as 1.0:1.8:0.6 when prepared as an organic phase after vigorous mixing of concentrated HNO3 and TBP. The HNO3 consumption was approximately 4 times the amount of extracted uranium. In designing a supercritical fluid extraction process, the following equation can be used to describe the overall dissolution of UO2 using the TBP complex with HNO3 and H2O in SF-CO2:

High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stability

Mesoporous molecular sieves like SBA-1, SBA-3, MCM-41 and MCM-48 are generally synthesized by using a quaternary ammonium surfactant as a structure-directing agent to form a porous silica framework. The used templating agent is conventionally removed for producing mesopores by calcination at high temperature. In this study, supercritical fluid extraction (SFE) has been employed to remove organic templates from these materials. We found that more than 80% of the templating agent can be successfully removed by using this technique. Among these materials, SBA-3 was observed to experience the collapse of mesoporous structures upon the SFE process. Thus, we have proposed pre-SFE thermal aging as a curing treatment method and found that it has significantly improved the mesoporous structural stability of SBA-3. In the meantime, this curing method has lead to these SFE-processed materials with better ordered mesoporous structures, such as SBA-3 having specific surface area as large as 1670 m 2/g.

Screening and confirmation of PAHs in vegetable oil samples by use of supercritical fluid extraction in conjunction with liquid chromatography and fluorimetric detection

Abstract A fast, simple, non-destructive method for the direct screening of polycyclic aromatic hydrocarbons (PAHs) in vegetable oil samples is proposed. The method uses a supercritical fluid extraction (SFE) system coupled on-line with a fluorimetric detector to determine PAHs. This special assembly avoids the main problems encountered in the determination of PAHs in complex matrices such as vegetable oils. PAHs are selectively extracted by using silica gel in the thimble and cleaned up by passage through a C18 column. Interferences are preferentially retained by the silica gel during the SFE process while PAHs are adsorbed in the C18 column and the remainder of the matrix is sent to waste. Finally, the C18 column is purged to remove residual CO2 gas and adsorbed PAHs are recovered by desorption with a solvent. The extracts from positive samples are subsequently analyzed by liquid chromatography (LC) with fluorescence detection. The proposed method allows the confirmation of vegetable oil safety and hence provides a new tool for consumer protection.

The Effect of the Oil and Supercritical Fluid CO2 Extract of Juniperus rigida Sieb. on the Growth Performance of Rat Adrenal Nerve Cells

It has been shown that the composition of the oils acquired by conventional steam distillation oil isolation (SDE) process was different from that obtained by supercritical fluid extraction (SFE) process for many kinds of plants. However, it has not been well investigated that the correlation between the differences of oil compositions and their biological efficacy by simultaneously comparing these variables, even though the extract from SFE is used in many oil industries. The oils from the two extraction processes contain similar amounts of three major components such as α-pinene, myrcene and terpinolene; however, the oils by SFE had higher amounts of fatty acids and only citronellol. That may be one reason that the flavor from each process was very different. The extraction yield by SFE method was higher than by SDE, maintaining 0.054% (v/v) vs 0.032% (v/v), respectively. In general, the extracts from SFE process can produce better growth performance of nerve cells such as cell growth, initiation and elongation of the neurites, followed by that from SDE, compared to the results without supplementation (control). It was interesting that the oils could play an important role in enhancing the initiation of the neurites as well as improving the growth of the nerve cells. It was also found that the oils by SFE took only 20 min to react with the cells while the control took 160 min by kinetic analysis of the oils responding to the cells. The extracts by SFE process definitely delayed apoptotic death of nerve cells, which could result in maintaining better cell growth and higher elongation of the neurites of the cell.

Simulation modeling of the phase behavior of palm oil‐supercritical carbon dioxide

AbstractThe phase behavior of crude palm oil (CPO) with supercritical CO2 was successfully modeled in an Aspen Plus® 10.2.1 commercial simulator (Aspen Technology Inc., Cambridge, MA) using the Redlich‐Kwong‐Aspen (RKA) equation of state thermodynamic model. The modeling procedure involved estimating pure component vapor pressures and critical properties and computing a regression of phase equilibrium behavior. The interaction parameters for the RKA model were obtained from the regression of experimental phase equilibrium data for a binary system of palm oil components‐supercritical CO2 available in the literature. The distribution coefficients and solubilities of palm oil components obtained from this simulation showed good agreement with experimental data obtained from the literature. The model provides an efficient and cost‐effective alternative for the preliminary design and optimization of a supercritical fluid extraction process involving a complex CPO‐supercritical CO2 system.

Concentration of Polar MFGM Lipids from Buttermilk by Microfiltration and Supercritical Fluid Extraction

Buttermilk contains the milk fat globule membrane (MFGM), a material that possesses many complex lipids that function as nutritionally valuable molecules. Milk-derived sphingolipids and phospholipids affect numerous cell functions, including regulating growth and development, molecular transport systems, stress responses, cross membrane trafficking, and absorption processes. We developed a two-step method to produce buttermilk derivative ingredients containing increased concentrations of the polar MFGM lipids by microfiltration and supercritical fluid extraction (SFE). These processes offer environmentally benign alternatives to conventional lipid fractionation methods that rely on toxic solvents. Firstly, using a ceramic tubular membrane with 0.8-μ pore size, we evaluated the cross flow microfiltration system that maximally concentrated the polar MFGM lipids using a 2n factorial design; the experimental factors were buttermilk source (fresh, or reconstituted from powder) and temperature (50°C, and 4°C). Secondly, a SFE process using supercritical carbon dioxide removed exclusively nonpolar lipid material from the microfiltered buttermilk product. Lipid analysis showed that after SFE, the product contained a significantly reduced concentration of nonpolar lipids, and a significantly increased concentration of polar lipids derived from the MFGM. Particle size analysis revealed an impact of SFE on the product structure. The efficiency of the SFE system using the microfiltration-processed powder was compared much more favorably to using buttermilk powder.

Supercritical fluid extraction process for removing polychlorinated biphenyl from a DOE job control waste

AbstractA supercritical carbon dioxide process has been investigated for remediation of polychlorinated biphenyl (PCB) contaminated Job Control Wastes at DOE sites. A PCB surrogate, 2‐chlorobiphenyl, was spiked into Toxi‐dry, a commercial absorbent material used extensively for decontaminating and decommissioning at DOE sites. Supercritical carbon dioxide extraction of 2‐chlorobiphenyl from Toxi‐dry was conducted with pure or ethanol‐modified carbon dioxide in bench‐scale units. Extraction temperatures, pressures, and time were varied to identify favorable operating conditions, and the effects of cosolvent and extraction time on supercritical extraction of PCBs were also investigated. About 95% of 2‐chlorobiphenyl was extracted from Toxi‐dry by CO2 modified with 5% EtOH, compared to just 53% with pure CO2 at the same pressure and temperature. While increasing temperature from 40°C to 80°C showed a clear improvement on extraction, increasing pressure from 2,000 psi to 4,000 psi does not significantly improve extraction efficiencies. Increasing extraction time from 2 hours to 3 hours does not increase the removal efficiency. The results demonstrate the potential of modified supercritical CO2 extraction as a PCB extraction technology for DOE PCB‐contaminated Toxi‐dry.