Supercritical Carbon Dioxide Fractionation Research Articles

Supercritical carbon dioxide fractionation of bio-crude produced by hydrothermal liquefaction of pinewood

The supercritical carbon dioxide extraction of bio-crude, produced by hydrothermal liquefaction of lignocellulosic biomass, was investigated for pressures and temperatures in the range 112–400 bar and 40–120 °C, corresponding to solvent densities in the range 548–882 kg/m3. Total extraction yields ranged from 17 to 42%. For a given solvent density, temperature increase drastically improved both the process operability and efficiency. The extracts showed reduced density as well as 40% reduction of total acid number compared to the feed. The residue resulted to be partially deoxygenated. Ketones, 1-ring phenols and low molecular weight fatty acids were concentrated in the extract, with recoveries up to 80%, with ketones and phenols exhibiting the highest distribution factors. Observed selectivities suggest the feasibility of downstream separation of the key classes of extractives using supercritical carbon dioxide as a solvent.

Supercritical carbon dioxide fractionation improves the antioxidative activity, anti-inflammatory activity, and therapeutic index of <em>Panax ginseng</em>

Supercritical carbon dioxide fractionation improves the antioxidative activity, anti-inflammatory activity, and therapeutic index of Panax ginseng Chao-Chin Yang,1 Chiu-Yuan Chen,2 Zer-Ran Yu,3 Be-Jen Wang1 1Department of Food Science, National Chiayi University, Chiayi, 2Department of Natural Biotechnology, Nanhua University, Dalin, Chiayi, 3Superwell Biotechnology Corporation, Taichung, Taiwan, Republic of China Abstract: Supercritical carbon dioxide (SC-CO2) fractionation technology can effectively separate different types of ginsenosides from the roots of Panax ginseng, which have been shown to possess various physiological activities. The objective of this study was to evaluate the antioxidative and anti-inflammatory activities as well as the therapeutic index of SC-CO2 fractions from P. ginseng C.A. Meyer. Of the various extracted fractions and residues, the F3 fraction exhibited the highest antioxidative property. The half maximal effective concentration (EC50) values of the F3 fraction for reducing power, hydrogen peroxide scavenging activity, and thiobarbituric acid assay were 4.51, 2.60, and 0.22 mg/mL, respectively. The F3 fraction also possessed the strongest anti-inflammatory effect in lipopolysaccharide-stimulated human THP-1 monocytic-like cell line, by decreasing tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) production. In addition, the F3 fraction exhibited a high therapeutic index, which is the ratio of 50% cytotoxic concentration (CC50) and EC50. In conclusion, high antioxidative and anti-inflammatory activities and therapeutic index value were observed in the F3 fraction of the roots of P. ginseng C.A. Meyer. SC-CO2 technology is a feasible method to improve the antioxidative and anti-inflammatory activities of P. ginseng. Keywords: anti-inflammation, antioxidative activity, Panax ginseng, supercritical carbon dioxide fractionation

Panax ginseng Fraction F3 Extracted by Supercritical Carbon Dioxide Protects against Oxidative Stress in ARPE-19 Cells.

In our previous work, the ethanolic extract of Panax ginseng C. A. Meyer was successively partitioned using supercritical carbon dioxide at pressures in series to yield residue (R), F1, F2, and F3 fractions. Among them, F3 contained the highest deglycosylated ginsenosides and exerted the strongest antioxidant and anti-inflammatory activities. The aim of this study was to investigate the protective effects of P. ginseng fractions against cellular oxidative stress induced by hydrogen peroxide (H2O2). Viability of adult retinal pigment epithelium-19 (ARPE-19) cells was examined after treatments of different concentrations of fractions followed by exposure to H2O2. Oxidative levels (malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), and reactive oxygen species (ROS)) and levels of activity of antioxidant enzymes were assessed. Results showed that F3 could dose-dependently protected ARPE-19 cells against oxidative injury induced by H2O2. F3 at a level of 1 mg/mL could restore the cell death induced by H2O2 of up to 60% and could alleviate the increase in cellular oxidation (MDA, 8-OHdG, and ROS) induced by H2O2. Moreover, F3 could restore the activities of antioxidant enzymes suppressed by H2O2. In conclusion, F3 obtained using supercritical carbon dioxide fractionation could significantly increase the antioxidant capacity of P. ginseng extract. The antioxidant capacity was highly correlated with the concentration of F3.

Supercritical carbon dioxide fractionation of peppermint oil with low menthol content – Experimental study and simulation analysis for the recovery of piperitenone

Low-menthol or dementholized oils can be regarded as potential sources of biocidal compounds, particularly monoterpenic ketones such as menthone, piperitone, piperitenone, pulegone and carvone. In this work, the recovery of piperitenone from peppermint oil by supercritical carbon dioxide fractionation is studied. Separation selectivity and gas loading measurements were performed in a semicontinuous high-pressure apparatus in order to evaluate the effect of temperature and solvent density on these properties. Semicontinuous fractionation was also carried out at a fixed temperature (313K) and pressure (85bar), collecting and analyzing extract samples until a purified piperitenone raffinate was obtained. The phase behavior of the system was modeled and predicted with the group contribution equation of state (GC-EOS). Good agreement with the experimental results was obtained. Finally, a continuous countercurrent multistage fractionation process was simulated, based on the GC-EOS model. The effect of operation temperature and pressure, solvent-to-feed ratio and reflux ratio was studied for different purity and recovery requirements and oil feed compositions.

Supercritical carbon dioxide fractionation of T. minuta and S. officinalis essential oils: Experiments and process analysis

Essential oils are an important source of compounds with different degree of biocidal activity against microorganisms, insects, weeds and other pathogens. They have potential application in pharmaceutical, cosmetic and food industry, as well as for agriculture and crop protection. Supercritical fluid fractionation is an interesting technology for the selective removal of monoterpenes (MT) and the purification or enrichment of the more bioactive oxygenated terpenes (OT), resulting in more effective, stable and water soluble products. In this work, the fractionation of Tagetes minuta and Salvia officinalis essential oils with carbon dioxide is experimentally studied in a semicontinuous apparatus at 313K and 80bar. Successive extracts are collected and the composition determined by gas chromatography. Process behavior is modeled with the group contribution equation of state (GC-EOS), showing a good agreement between model predictions and experimental results. The GC-EOS model is applied to the simulation and analysis of two continuous fractionation schemes: a simple countercurrent column and a countercurrent column with external reflux. The influence of operation variables (temperature, pressure, solvent-to-feed ratio, thermal gradient, reflux ratio) is studied in order to maximize OT concentration and recovery in the raffinate and to minimize carbon dioxide consumption. Experimental and simulation results are discussed in terms of the relative volatilities between MT and OT fractions. Particularly in the case of S. officinalis, the presence of several OT of intermediate volatility and a significant amount of higher molecular weight sesquiterpenes (ST) limits the separation performance, even when external reflux is applied.

Continuous extraction of glycerol acetates from their mixture using supercritical carbon dioxide

Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixture of triacetin, diacetin, and monoacetin with a molar ratio of 1:2:1. The extraction was carried out in two stages. In the first stage, a central composite design was used to optimize the four variables of pressure, temperature, liquid CO2 flow rate, and extraction time at three levels using a semi-continuous, supercritical carbon dioxide extraction setup. The composition of the extract under the predicted optimum conditions (i.e., 109bar, 56°C, 0.86mLmin−1, and 61min) was about 69% triacetin accompanied by only 30% diacetin and no detectable monoacetin. In the second stage, the effect of the two factors, pressure (100, 109, and 140bar) and liquid CO2 flow rates of 0.86 and 1.5mLmin−1 measured at average laboratory temperature (27°C) and pressure (0.89bar), were studied using a continuous, supercritical carbon dioxide fractionation setup equipped with a glass-bead packed column kept under a thermal gradient of 56–70°C. The experimental design was organized as a 3×2 general factorial design. Under the best conditions (i.e., 140bar and 1.5mLmin−1), the extraction yield of triacetin and diacetin were 41.8 and 3.0%, respectively, without any detectable monoacetin as verified by GC-FID.

Supercritical Carbon Dioxide Fractionation of Nonesterified Alkoxyglycerols Obtained from Shark Liver Oil

Ethanolysis of shark liver oil was carried out to generate a product enriched in nonesterified alkoxyglycerols and fatty acid ethyl esters. For the present study, the original oil contained very low amounts of squalene, and thus, unsaponifiable matter was mainly constituted by nonesterified alkoxyglycerols (NEAKG). A small percentage of monoesterified alkoxyglycerols (MEAKG) was also detected. Supercritical fluid extraction was employed to fractionate the mixture, achieving a complete elimination of esters and concentrating the alkoxyglycerol compounds in the raffinate product. Extractions were carried out in a countercurrent packed column, using extraction pressures in the range of 140-180 bar, temperatures from 45 to 65 degrees C, and a solvent-to-feed ratio of 15. NEAKG + MEAKG purity obtained in the raffinate at the best extraction conditions was around 78% w/w, and satisfactory yield (>60%) was also achieved. Therefore, the raffinate product can be re-esterified to design highly valuable ether lipid compounds.

Supercritical carbon dioxide fractionation of Lavandin essential oil: Experiments and modeling

The two main components of Lavandin essential oil are linalool and linalyl acetate. These components have different applications in the food and fragrance industry, and also for producing natural herbicides and insecticides in the case of linalool. Thus there is a commercial interest in the separation of the essential oil into linalool- and linalyl acetate-rich fractions. This work presents a study of this fractionation using supercritical CO 2 in a continuous operating high-pressure counter-current packed column. The influence of process parameters like flowrate, pressure and temperature has been determined. The separation is limited by the low gas load achieved, and it has been observed that in order to increase the load, high temperatures and CO 2/oil phase ratios were necessary with operating pressures close to the mixture critical point. Additionally, a detailed mathematical model of the fractionation column has been developed and validated with the pilot plant results. This model has been used to study the operation with conditions that exceed the capabilities of the pilot plant such as a higher CO 2/oil phase ratio or a longer fractionation column, and to propose the optimum conditions for this fractionation.

Supercritical carbon dioxide fractionation of the model mixture squalene/oleic acid in a membrane contactor

Six different membranes were tested at 18.0 MPa and 313 K for their performance to fractionate a model mixture of squalene/oleic acid with supercritical carbon dioxide. A significant enrichment of squalene in the permeate side was achieved with a 10 μm-coating layer polydimethyl siloxane (PDMS) membrane at the tested conditions although with the drawback of a lower total permeate flux. Additional fractionation experiments of the same model mixture were carried out in a countercurrent packed column at 18.0 MPa of pressure and 313 and 323 K of temperature. At a solvent-to-feed mass flow ratio of ca. 40 an extraction efficiency of 88% of the total mass of squalene fed to the column was obtained at 18.0 MPa/313 K. The raffinate and extract streams obtained at these conditions had a squalene content of 10 and 63.5 wt%, respectively. An optimized combination of supercritical extraction and membrane separation could be used to increase the purity of the extract stream in squalene.

Supercritical carbon dioxide fractionation of fish oil fatty acid ethyl esters

Fractionation of fish oil fatty acid ethyl esters was investigated with the aim of obtaining a lipid fraction enriched in ω-3 fatty acids and with a suitable EPA/DHA ratio. The results obtained highlight the possibility of modifying the original fatty acid ethyl esters concentration by optimizing the extraction conditions in terms of pressure, temperature, and supercritical carbon dioxide flow rate. Supercritical fluid fractionation (SFF) appears to be a useful processing technique for changing the composition of lipids in order to obtain high value functional products. The use of proper fractionation temperatures and pressures along the column influenced the solvent-to-feed ratio to obtain fractions with suitable composition for market requirements.

Supercritical carbon dioxide fractionation of lemon oil by means of a batch process with an external reflux

The deterpenation of cold-pressed lemon peel oil by means of supercritical carbon dioxide was carried out both in a simple batch mode and by means of a batch process with a rectification column. The simple batch process provided experimental data of vapour phase loading at temperature 315–323–333 K and pressure ranging from 8.4 to 10.5 MPa. This process allowed the production of folded oils with reasonable solvent to feed ratio, but led to low recovery of oxygenated compounds in the raffinate. In order to increase the recovery of these valuable compounds, a batch process with an external reflux of extract was performed in a laboratory plant, investigating the effect of temperature, pressure and reflux ratio. The operational conditions that led to lower solvent to feed ratio, for a stated oxygenated concentration in the raffinate, were found at temperature of 333 K and pressure around 10.0 MPa. The obtained values for the recovery of oxygenated compounds ranged from 0.82 to nearly 1, with a reflux ratio varying from 1.4 to 9.

A continuous countercurrent supercritical fluid deacidification process for phytosterol ester fortification in rice bran oil

This study examines the potential of a continuous countercurrent supercritical carbon dioxide fractionation technique for deacidification of crude rice bran oil. A pilot scale packed column was utilized for the experiments. It was shown that fractionation at low pressure, 138 Bar, and high temperature, 80 °C, effectively removed free fatty acids from crude rice bran oil without any oryzanol loss in the extract fraction. Oryzanol content of the raffinate fraction was three times higher than that of the feed material. Phytosterol fatty acid ester content of the raffinate fraction was also increased during the deacidification process, however the enrichment of these moieties was not as high as that found for oryzanol.

Phytosterol Enrichment of Rice Bran Oil by a Supercritical Carbon Dioxide Fractionation Technique

ABSTRACT:Supercritical carbon dioxide (SC–CO2) fractionation technique was evaluated as an alternative process for reducing the free‐fatty‐acid (FFA) content and minimizing the phytosterol loss of rice bran oil (RBO) during the process. The effects of pressure (20.5 to 32.0 MPa) and temperature (45 to 80 °C) for isothermal operation of the column on the composition of the resultant fractions were examined. Low‐pressure and high‐temperature conditions were found to be favorable for minimizing triglycerides (TG) and phytosterol losses during the FFA removal from crude RBO. Rice bran oil fractions with < 1% FFA, about 95% TG, and 0.35% free sterol with 1.8% oryzanol content could be obtained utilizing the described SC–CO2 fractionation technique.

OAT LIPIDS - INTERACTION WITH WATER AND CHARACTERIZATION OF AQUEOUS PHASES

ABSTRACT The physical properties of oat lipids have been investigated in order to understand their functional significance during processing. This work concerns one oat variety with a high lipid content and another with low content. The lipids were characterized chemically, and phase equilibria with water were studied by supercritical carbon dioxide fractionation into polar and non-polar components. Structures of the phases were identified by X-ray diffraction. The lamellar liquid-crystalline phase has a dominating existence range in the phase diagrams, and in this respect oat lipids are different than other cereal lipids.