| 1. |
- da Cruz Francisco, José, et al.
(författare)
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Gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 22:3, s. 247-254
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Tidskriftsartikel (refereegranskat)abstract
- The gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide was investigated using light microscope. The starch was placed in a stainless steel chamber at atmospheric pressure and high CO2 pressures, 8 and 30 MPa as well as at 8 MPa N-2 and the gelatinization degree observed by light microscopy. The results showed that both pressure and supercritical fluid affected the gelatinization degree. Cassava and potato starches showed a lowering of the gelatinization temperatures at 8 MPa and an increasing at 30 MPa as compared with the gelatinization degree at atmospheric pressure. For wheat starch, the decrease in the gelatinization temperature occurred in the same direction as the pressure increased, in comparison with the atmospheric pressure conditions. However, between the two applied pressures, there was a larger increase of the gelatinization temperature at 30 MPa than at 8 MPa. The effect of hydrostatic pressure component of the CO2 was evaluated by using N-2 at 8 MPa. The replacement of CO2 by N-2 at 8 MPa increased the gelatinization temperature for all the studied starches compared with the atmospheric conditions. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
- da Cruz Francisco, José, et al.
(författare)
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Solubility of three monoterpenes, their mixtures and eucalyptus leaf oils in dense carbon dioxide
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 23:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- The solubility of 1,8-cineole, alpha-pinene, limonene, their mixtures and the extract of eucalyptus leaf oils in supercritical carbon dioxide were determined using the dynamic method at 80, 100, 150, and 250 bar and 40 and 60 degreesC for each pressure. The results showed an increase in the solubility of all oils with an increase in pressure and a decrease with temperature. The mixtures of both pure blends as well as the eucalyptus oil extracts exhibited lower solubility than the pure single oil components in the same conditions. The oil of E. radiata exhibited a better separation of 1,8-cineole at 80 bar and 60 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 3. |
- Dauksas, E, et al.
(författare)
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Effect of fast CO2 pressure changes on the yield of lovage (Levisticum officinale Koch.) and celery (Apium graveolens L.) extracts
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 22:3, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pressure alterations on the yield of CO2, extracts from different anatomical parts of lovage (Levisticum officinale Koch.) and celery (Apium graveolens L.) was studied. It was found that by applying frequent pressure changes in the extraction vessel it is possible to increase the rate of the isolation of CO2 soluble materials from lovage seeds and leaves, lovage and celery roots. However, after passing a sufficient amount of the supercritical solvent, the yields were similar both for constant and pulsing extraction pressures. The composition of the extracts was analyzed by gas chromatography and mass spectrometry and it was found that the phthalides were very important constituents in the extracts from all the anatomical parts of lovage, while linoleic acid was the most abundant component in the celery root extracts. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 4. |
- Dauksas, E, et al.
(författare)
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Supercritical fluid extraction of borage (Borago officinalis L.) seeds with pure CO2 and its mixture with caprylic acid methyl ester
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 22:3, s. 211-219
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Tidskriftsartikel (refereegranskat)abstract
- The influence of different pressures of CO2 and the addition of caprylic acid methyl ester as an entrainer was studied for the extraction process of borage seed. The increase of CO2 pressure from 100 to 350 bar resulted in the increase in extract yield from 0.14 to 24.29% (w/w) while the changes in the extract composition were not so considerable. The highest solubility of pure caprylic acid methyl ester in dense CO2 was determined at 100 and 300 bar (approximately 1 g of ester in 1 g of CO2). The addition of this entrainer increased the yield of pure extract up to 47.8 times at 100 bar, 2.4 times at 200 and 300 bar. Due to the high solubility of caprylic acid methyl ester at the lower (100 bar) pressure it is easy to separate the entrainer, which constituted only 4.22% of the total borage seed extract. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 5. |
- Abrahamsson, Victor, et al.
(författare)
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Continuous multicomponent quantification during supercritical fluid extraction applied to microalgae using in-line UV/Vis absorption spectroscopy and on-line evaporative light scattering detection
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 131, s. 157-165
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Tidskriftsartikel (refereegranskat)abstract
- A quantitative methodology based on in-line UV/Vis absorption spectroscopy and on-line evaporative light scattering detection for supercritical fluid extraction is proposed. The method was applied to the extraction of carotenoids, chlorophyll A, ergosterol and total lipids from microalgae. One regression technique and two curve resolution techniques were applied on the absorption spectroscopy data and evaluated, namely classical least squares, multivariate curve resolution by alternating least squares and parallel factor analysis (PARAFAC2). The two former both generated useful models, furthermore multivariate curve resolution also successfully enabled estimation of both spectra and concentration profiles of the analytes. The integrated extraction profiles of each analyte were compared with analysis of the collected fractions using reference analysis methods Precision, in regards to quantification of the analytes in the eluent, was better using in-line measurements compared to off-line measurements by UV/Vis absorption spectroscopy, supercritical fluid chromatography with mass spectrometry and liquid chromatography with UV/Vis detection.
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| 6. |
- Abrahamsson, Victor, et al.
(författare)
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Method development in inverse modeling applied to supercritical fluid extraction of lipids
- 2016
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 111, s. 14-27
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Tidskriftsartikel (refereegranskat)abstract
- Modeling of the supercritical fluid extraction of solid materials is an important aspect in order to understand and predict the process. A comparison of two empirical models, two semi-empirical models and two mechanistic models is performed using calibration of single experiments. It is concluded that the best fit is obtained using a simple empirical expression. Furthermore, single calibrations did not generate reliable parameters with physical meaning and a methodology is proposed for inverse modeling with complete calibration using several experiments. The experimental dataset contained 29 extractions of lipids from crushed linseeds with varying temperatures, pressures and flow rates. A general rate model and a proposed extension of the hot ball model were evaluated for this purpose. The methodology includes data acquisition, model structure estimation, model calibration and a cross-validation. In general, it was found that the solubility model of Sovová outperformed the other evaluated correlations, and for the general rate model the Toth partition isotherm was also found in the top model structures. However, no generalization could be made regarding the correlations describing the Nernst diffusion layer and diffusivity.
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| 7. |
- Abrahamsson, Victor, et al.
(författare)
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Multicomponent inverse modeling of supercritical fluid extraction of carotenoids, chlorophyll A, ergosterol and lipids from microalgae
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 139, s. 53-61
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Tidskriftsartikel (refereegranskat)abstract
- The fundamentals of analyte extractable fraction, solubility, partitioning and mass transfer resistance in supercritical fluid extraction were studied using inverse modeling. These phenomena are essential for understanding, predicting and optimizing the supercritical fluid extraction process. Carotenoids, chlorophyll A, ergosterol and total lipids were extracted from the microalgae Chlorella sp. The analytes were measured continuously in-line and on-line using UV/Vis absorption spectroscopy measurements and by evaporative light scattering detection. Various pressures, temperatures, flow rates and fractions of ethanol as a co-solvent were evaluated. The extractable fraction of carotenoids, chlorophyll A and total lipids were dependent on the co-solvent fraction in the extraction phase. The additional amount that could be extracted by using more co-solvent followed a normal distribution, indicating that analytes should not simply be categorized into weakly or strongly bound. The characteristics of diminishing extraction rates over time was accounted for by analyte partitioning rather than intra-particle diffusion limitations.
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| 8. |
- Andersson, Martin, et al.
(författare)
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Dynamic pH determination at high pressure of aqueous additive mixtures in contact with dense CO2
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 136, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- A system consisting of a high-pressure tolerant microfluidic glass chip, high-speed absorbance imaging, and image processing has been developed to study rapid dynamic events like pH change in a multiphase flow. The system gives both kinetic and quantitative equilibrated information. By tracking the interactions of aqueous additive mixtures and liquid CO2, at 80 bar and 24 °C, under flow, measurement at a given P, T condition is done in 0.25 s. The acidification rate to steady state was found to be mass transport limited, occurring in less than 1 s. For 30 mM of the additives ammonium acetate and ammonium formate, equilibrium pH of 4.5 and 4.1, respectively, was seen. These additives are of key importance in common mobile phases used in SFC.
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| 9. |
- Cui, Jingwen, et al.
(författare)
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Measurement of relative static permittivity and solvatochromic parameters of binary and ternary CO2-expanded green solvents
- 2021
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 171
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Tidskriftsartikel (refereegranskat)abstract
- CO2-expanded liquids (CXLs) is a class of solvent systems giving relatively low viscosity in comparison to neat organic solvents. The challenge is to achieve a high overall polarity of the CXL, despite the presence of compressed liquid CO2. In this study, the relative static permittivity (εr) was measured for binary and ternary one-phase mixtures of CO2 + green solvent using an in-line microfluidic device. In addition, Kamlet-Taft solvatochromic parameters were experimentally determined, allowing the characterization of the polarizability, acidity, and basicity. Novel data is shown for binary and ternary systems of CO2 expanded ethanol and ethyl lactate, with or without glycerol or water added, at moderate conditions of pressure and temperature (8 MPa and 35 °C). One-phase CXLs systems of a wide relative permittivity range (7.7–75.3) at lowered viscosity were enabled, by mixing different green solvents with CO2.
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| 10. |
- Cunico, Larissa P., et al.
(författare)
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Enhanced distribution kinetics in liquid-liquid extraction by CO2-expanded solvents
- 2020
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 163
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Tidskriftsartikel (refereegranskat)abstract
- Liquid-liquid extraction (LLE) is a useful extraction technique for highly complex samples, however, it suffers from being slow due to mass transfer limitations. Carbon dioxide expanded liquids (CXL) is a good replacement of traditional organic solvents for extraction, and for the first time, the use of CXL in LLE was evaluated. An equipment consisting of a high-pressure view cell with on-line gas chromatography analysis was built and validated, and thereafter used to obtain novel phase equilibria data of the CO2/n-octanol/water system. The system was connected on-line to HPLC to study the potential of CO2-expanded liquid-liquid extraction (CXLLE) of pharmaceutical contaminants in water. In comparison with traditional LLE performed under similar experimental conditions, the addition of CO2 as a viscosity-lowering entrainer significantly increased the speed of mass transfer. Changes in compound log D (octanol-water distribution ratio) values brought by the CO2 expansion also proved the possibility of selectivity-tuning in CXLLE.
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