Browsing by Author "del Valle, Jose M."

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    Correlation for the variations with temperature of solute solubilities in high temperature water
    (ELSEVIER, 2011) del Valle, Jose M.; de la Fuente, Juan C.; Srinivas, Keerthi; King, Jerry W.
    Methods for estimating solute solubilities in high temperature water both below and above its boiling point (under pressure) are needed for applications of this medium in processing applications such as sub-critical water extraction, reaction chemistry in heated water, and in the material sciences. There is a paucity of data and correlative methods for estimating solute solubilities under these conditions; the limited existing methods are based on a limited solubility data base, and in some cases predicted solubility values are in quite serious disagreement with experimentally derived data. Here available solute solubility data both above and below the boiling point of water has been correlated for diverse solute types consisting of hydrocarbons, essential oil components, pesticides, polyphenolic compounds, as well as solutes exhibiting high solubility in water under the stated conditions. Utilizing solubility data from diverse sources, appropriate conversions and equations have been derived for converting all solubility data to a mole fraction basis, while the other required physicochemical parameters, such as melting point, boiling point, critical properties, have been estimated, when necessary, largely by group contribution-based methods. A solubility model based on such physicochemical parameters and critical properties of the solutes was derived. An excellent correlation is obtained for x(c)(estimated) versus x(c) using this approach and the prediction of solute solubility in water as a function of temperature was found to be excellent for 431 data points representing the solubility of 34 solutes in the temperature range between 298 and 573 K. (C) 2010 Elsevier B.V. All rights reserved.
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    Effect of heat transfer on the pressurization, extraction, and depressurization stages of a supercritical CO2 2 extraction process. 2. Simulation of a two-vessel industrial plant
    (2024) Toledo, Felipe R.; del Valle, Jose M.
    In this work, we simulated the heat transfer in a two-vessel (1-m3, 3 , length-to-diameter ratio of 4) industrial plant to assess the effect of the temperature gradients formed during the reconditioning stage on the extraction curves. We simulated the extraction of 1-mm particles using 5 mm/s of CO2 2 at 48 MPa and 40 degrees C (case with an imposed temperature gradient) or 60 degrees C (case with temperature gradients from the reconditioning stage), with the service fluid at 60 degrees C. The results of these non-isothermal extractions were compared with those obtained in representative isothermal cases. The temperature gradients slightly affected the cumulative extraction curves in non- isothermal cases. We considered the presence of a basket containing the solid substrate. We also changed the superficial CO2 2 velocity to 3 or 10 mm/s and the particle size to 0.50 or 1.25 mm to compare the extraction curves. The effects of the basket and the changes in superficial CO2 2 velocity and particle size were minor. We simulated a limit case with higher temperature and pressure (80 degrees C and 70 MPa), where the extraction time was extremely short (10 min) and more significant temperature gradients were formed during the reconditioning stage. We observed more significant differences at this extreme extraction condition than when using an isothermal process at the required extraction temperature.
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    Effect of triolein addition on the solubility of capsanthin in supercritical carbon dioxide
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2012) Araus, Karina A.; del Valle, Jose M.; Robert, Paz S.; de la Fuente, Juan C.
    This manuscript presents new phase equilibrium data for capsanthin in pure and triolein-entrained Supercritical (SC) carbon dioxide (CO2). The aim of the work was to determine the cosolvent effect of triolein on capsanthin by comparing solubility results in a ternary (CO2 + triolein + capsanthin) system and binary (CO2 + capsanthin) system at (313 or 333) K and (19 to 34) MPa. For this, authors isolated capsanthin from red pepper (Capsicum annuum L.) and tested it using a dynamic-analytical method in an apparatus with recirculation and online analysis of the CO2-rich phase. Within the experimental region, the solubility of capsanthin in pure SC-CO2 increased with system temperature at isobaric conditions and also increased with pressure at isothermal conditions. Solubilities ranged from a minimal of 0.65 mu mol/mol at 313 K and 19 MPa to a maximal of 1.97 mu mol/mol at 333 K and 32 MPa. The concentration of triolein in the ternary system was equivalent to that its solubility in pure SC-CO2 depending on system temperature and pressure conditions. Crossover pressure was determined experimentally at 29.6 MPa, below which solubility of triolein decreased with temperature (effect of density). Above the crossover pressure, solubility of triolein increased with temperature (vapor pressure effect). Values of solubility within this range were 0.16 mmol/mol at 19 MPa and 313 K to 0.41 mmol/mol at 33 MPa and 333 K. Independent of system temperature and pressure, capsanthin solubility in triolein-entrained SC-CO2 increased by a factor of about 3 (triolein-induced enhancement factor) as compared to its solubility in pure CO2, under similar conditions of pressure and temperature. The maximal solubility of capsanthin in SC-CO2 experimentally observed in this study was 5.27 mu mol/mol at 333 K and 33 MPa in the presence of 4.10 mmol/mol triolein. (C) 2012 Elsevier Ltd. All rights reserved.
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    Experimental measurement and modeling of the solubility of fluorinated compounds derived from dichlone in supercritical carbon dioxide
    (2024) Arevalo, Vicente D.; Cabrera, Adolfo L.; Zacconi, Flavia C.; Morales-Guerrero, Sebastian; del Valle, Jose M.; Taborga, Lautaro; de la Fuente, Juan C.
    Dichlone, also known as 2,3-dichloronaphthalene-1,4-dione, is a solid organic substance employed in the field of agriculture for its fungicidal properties and as a retardant for vegetable decomposition. The bioactive properties of dichlone can be enhanced by modifying its structure, specifically through the synthesis of new derivatives achieved by replacing the functional groups within its molecular structure. Two new solid dichlone derivatives were synthesized in this work, namely 2-chloro-3-((4-fluorobenzyl)amino)naphthalene-1,4-dione (dCl-2B-F) and 2-chloro-3-((4-fluorophenethyl)amino)naphthalene-1,4-dione (dCl-3 P -F) and measured their solubility in supercritical carbon dioxide at (313, 323, and 333) K and pressures between (9. to 32) MPa. The results indicated that solubility ranged between 30.5 and 47.9 mu mol of solute/mol of CO 2 for dCl-2B-F, and from 2.2 to 243.5 mu mol of solute/mol of CO 2 for dCl-3 P -F. The solubility data of dichlone and its synthesized derivatives (dCl-2B-F, dCl3 P -F, 2-chloro-3-((4-chlorobenzyl)amino)naphthalene-1,4-dione (dCl-2B-Cl), 2-chloro-3-((4-chlorophenethyl) amino)naphthalene-1,4-dione (dCl-3 P -Cl), 2-(benzylamino)-3-chloronaphthalene-1,4-dione (dCl-2B) and 2chloro-3-(phenethylamino)naphthalene-1,4-dione (dCl-3 P)) was compared using the density-based correlation of Chrastil and the Statistical Associating Fluid Theory of Variable Range Mie-potential (SAFT-VR Mie) equation of state (EoS), to better comprehend the effects of the structural differences on the solubility. As a result, for the Chrastil model, a root mean square deviation ( rmsd ) of 3% was obtained for dCl-2B-F and 16% for dCl-3 P -F, whereas for the SAFT-VR Mie equation, it averaged 24% for dCl-2B-F and 28% for dCl-3 P -F. It was found that the solubility of the homologous compounds, differing only in one methylene group, increased with solute size (-2B derivatives were less soluble in CO 2 than the -3 P ones), contrary to the expected trend, which could be attributed to the increased probability of ring -to -ring interactions as the chain length connecting the rings decreases. This demonstrates that geometric factors, along with the pressure and temperature, affect the behavior of the solubility and these should be accurately represented in the predictive models.
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    Extrusion affects supercritical CO2 extraction of red pepper (Capsicum annuum L.) oleoresin
    (2022) Uquiche, Edgar; Millao, Sonia; del Valle, Jose M.
    Carotenoids provide red colour and antioxidant properties in formulated foods. High-value, carotenoid-rich oleoresin can be extracted from red pepper using SuperCritical (SC) carbon dioxide (CO2). Densifying the solid substrate can overcome process limitations of batchwise operation to increase the extraction vessel load of red pepper. However, there is no information in literature on the effect of densifying treatments on the bioactive components of vegetable matrices. This work evaluated the effect of extrusion as a densification process on the yield and quality of SC-CO2-extracted red pepper oleoresin. A 23-factorial experimental design was used to study the effects of substrate pretreatment (control or extruded) and extraction temperature (40 or 60 degrees C) and pressure (30 or 50 MPa) on SC-CO2 extraction yield, and the extractable colour (ASTA units), carotenoid content, antioxidant activity (inhibition of a DPPH radical), and oxidative index (p-anisidine value) of the extracts. Extrusion had a significant (p <= 0.01) but negative effect on all responses. Independent of substrate pretreatment, SC-CO2 extraction yield and carotenoid yield where maximized at the extreme conditions of 60 degrees C and 50 MPa. The extractable colour and antioxidant activity correlated positively (p <= 0.05), and their oxidative index correlated negatively (p = 0.05) with the carotenoid content of the SC-CO2 extracts.
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    Mathematical simulation of heat and mass transfer during controlled depressurization of supercritical CO2 in extraction vessels
    (2017) Soledad Murias, M.; del Valle, Jose M.; Nunez, Gonzalo A.
    Even after almost forty years of industrial application, companies are still reluctant to use supercritical (sc) CO2 as a solvent for extractions due to the perceived high production costs. Literature on the matter suggests that, because extraction at high pressure needs to be done in batches, using multiple extraction vessels with simulated-countercurrent flow could reduce operational costs. However, the more extraction vessels used, the less time there is to recondition them in order to have a semi-continuous operation; and if the reconditioning, and particularly the depressurization, is done too fast, the vessel could become brittle and permanently damaged. With the goal of optimizing the depressurization process in mind, numerical simulation of temperature and mass was carried considering a 1-dm(3) vessel filled with a packed bed made with model materials using a mass flow function that depends on the chocked mass flux and a valve opening area. The correlation Nu = 0.0777 Da(-0.373) Ra-0.397 was obtained for convective heat transfer at the vessel wall, and temperature, pressure, and vented mass flow were simulated with about 20% improvement in predictions in comparison to our previous correlation. To explore the use of the model for practical purposes, it was used to simulate depressurization processes with volumes up to 1 m(3) and with different initial conditions and vessel geometries so as to have a first approach on the effect of these parameters on the depressurization time. Simulated depressurization times reached a maximum value of 54.5 min for depressurizations of a 1-m(3) extraction vessel starting at 60 degrees C and 70 MPa, which are very plausible extraction conditions. This model can be used to determine optimal reconditioning time in industrial plants for cost minimization. (C) 2016 Published by Elsevier B.V.
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    Matrix effects in supercritical CO2 extraction of essential oils from plant material
    (ELSEVIER SCI LTD, 2009) Araus, Karina; Uquiche, Edgar; del Valle, Jose M.
    In this work, we reviewed the effect of the solid matrix in the supercritical CO2 (SC-CO2) 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-CO2 phases is constant. The model was fitted to literature data from several plant materials (relevant solute identified between parenthesis): chamomile flowers (alpha-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 best-fit values of effective diffusivity of the Solute in the solid matrix (D-e) we estimated the value of the so-called 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. (c) 2009 Elsevier Ltd. All rights reserved
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    Simulation of a supercritical carbon dioxide extraction plant with three extraction vessels
    (PERGAMON-ELSEVIER SCIENCE LTD, 2011) Nunez, Gonzalo A.; Gelmi, Claudio A.; del Valle, Jose M.
    Although SuperCritical (SC) Fluid Extraction (SCFE) has been successfully applied commercially the last three decades, there is no systematic procedure or computational tool in the literature to scale-up and optimize it. This work proposes an algorithm to simulate dynamics in a multi-vessel (>= 3) high-pressure SCFE plant where extraction vessels operate in batches, and is thus forced to use simulated-countercurrent flow configuration to improve efficiency. The algorithm is applied to a three-vessel SCFE plant using a shrinking-core model to describe inner mass transfer in the substrate. As example, the extraction of oil from pre-pressed seeds using SC CO(2) at 313 K and 30 MPa is simulated. After three cycles the process reaches a pseudo-steady-state condition that simplifies the estimation of plant productivity. Use of a three-instead of two-vessel SCFE plant increases oil concentration in the stream exiting the plant and decreases CO(2) usage at the expense of increasing extraction time. (C) 2011 Published by Elsevier Ltd.
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    Solubilities in Supercritical Carbon Dioxide of (2E,6E)-3,7,11-Trimethyldodeca-2,6,10-trien-1-ol (Farnesol) and (2S)-5,7-Dihydroxy-2-(4-hydroxyphenyl)chroman-4-one (Naringenin)
    (AMER CHEMICAL SOC, 2010) Nunez, Gonzalo A.; del Valle, Jose M.; de la Fuente, Juan C.
    We measured the solubility in supercritical carbon dioxide (CO2) of farnesol [(2E,6E)-3,7,11-trimethyldodeca-2,6,10-trien-1-ol] and naringenin [(2S)-5,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one] using a static-analytic method (a high-pressure static equilibrium cell coupled to an HPLC). The molar fraction of farnesol in the saturated CO2-rich phase increased between y(2) = 0.13.10(-3) at 333 K and 11.4 MPa to y(2) = 1.91.10(-5) at 333 K and 26.0 MPa for farnesol and from y(2) = 0.49.10(-5) at 313 K and 10.3 MPa to y(2) = 1.65.10(-5) at 333 K and 44.5 MPa for naringenin. The average error of our measurements was about 25 To. Farnesol had an end-temperature crossover point at approximately 17 MPa, whereas naringenin exhibited a monotonous increase in solubility with both temperature and pressure. The differences in solubility between farnesol, naringenin, and other sesquisterpenes or flavonoids reported in the literature were partially explained by differences in molecular weight and polarity between solutes. We correlated experimental data as a function of the system temperature and pressure and the density of the solvent using a literature model that also showed the autoconsistency of the data for CO2 densities above 412 kg.m(-3) for naringenin.
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    Solubility in supercritical carbon dioxide of two novel amine derivatives of 2,3-dichloronaphthalene-1,4-dione (dichlone)
    (2023) Schulz, Alex C.; Zacconi, Flavia C.; Cabrera, Adolfo L.; del Valle, Jose M.; Espinoza, Luis; de la Fuente, Juan C.
    Dichlone (2,3-dichloronaphthalene-1,4-dione) is an important antimicrobial agent for agriculture, which effectiveness could be improved by modifying its structure, while the recovery of high-purity synthesized derivatives from a reaction mixture could be accomplished by extracting them with supercritical carbon dioxide. Two new amine derivatives, 2-chloro-3-((4-chlorobenzyl)amino)naphthalene-1,4-dione (dCl-2B-Cl) and 2-chloro-3-((4-chlorophenethyl)amino)naphthalene-1,4-dione (dCl-3P-Cl), were synthesized from dichlone, and their solubility in supercritical carbon dioxide was measured afterwards at (313, 323 and 333) K and a pressure range from (8-33) MPa. Experimental solubilities spanned from (10.3 center dot 10(-6) to 22.1 center dot 10(-6)) mol center dot mol(-1) for dCl-2B-Cl, and from (32.7 center dot 10(-6) to 131 center dot 10(-6)) mol center dot mol(-1) for dCl-3P-Cl. The solubility data of the dichlone family (dichlone, dCl-2B-Cl, dCl-3P-Cl, 2-(benzylamino)-3-chloronaphthalene-1,4-dione (dCl-2B) and 2-chloro-3-(phenethylamino)naphthalene-1,4-dione (dCl-3P)) was compared using three models, i.e., the Chrastil equation, the Molecular Connectivity Indices model, and the Statistical Associating Fluid Theory of Variable Range and Mie Potential equation of state, to identify the quantitative structure-property relationship between them. Solubility had an inverse relation with solute size and polarity, but there were some exceptions that could be explained by performing a stereochemical analysis, which showed that steric effects involved in the folding of dCl-3P and dCl-3P-Cl provided them a better geometry for solvation than dCl-2B and dCl-2B-Cl, respectively, making them more soluble. This demonstrates that the solute geometry is an important factor in the solvation process, and it must be represented accurately to develop better predictive models.
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    Solubility of 1,3-Dimethyl-7H-purine-2,6-dione (Theophylline) in Supercritical Carbon Dioxide
    (AMER CHEMICAL SOC, 2009) de la Fuente, Juan C.; Nunez, Gonzalo; del Valle, Jose M.
    This contribution provides complementary experimental data of solubility (y(2), molar fraction) of solid 1,3-dimethyl-7H-purine-2,6-dione (theophylline) in supercritical CO2 as a function of temperature (313 K <= T <= 333 K) and pressure (10 MPa <= P <= 44 MPa). A static-analytic methodology was used with standard deviations from average solubility measurements of <= 38% and with estimated inherit errors <= 25%. The solubility of theophylline increased with the CO2 density from 0.33.10(-5) mol.mol(-1) at 797.2 kg.m(-3) (313 K, 16 MPa) to 3.3.10(-5) mol.mol(-1) at 890.2 kg.m(-3) (333 K, 40 MPa). The solubility increased with pressure and temperature. Experimental solubilities were correlated with a density-based model with three adjustable parameters, which was valid for solvent densities in the range of (400 to 950) kg.m(-3).
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    Solubility of beta-carotene in ethanol- and triolein-modified CO2
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2011) Araus, Karina A.; Canales, Roberto I.; del Valle, Jose M.; de la Fuente, Juan C.
    Modification of an experimental device and methodology improved speed and reproducibility of measurement of solubility of beta-carotene in pure and modified SuperCritical (SC) CO2 at (313 to 333) K. Solubilities of beta-carotene in pure CO2 at (17 to 34) MPa ranged (0.17 to 1.06) mu mol/mol and agreed with values reported in literature. The solubility of beta-carotene in CO2 modified with (1.2 to 1.6) % mol ethanol increased by a factor of 1.7 to 3.0 as compared to its solubility in pure CO2 under equivalent conditions. The concentration of triolein in equilibrated ternary (CO2 + beta-carotene + triolein) mixtures having excess triolein reached values (0.01 to 0.39) mmol/mol corresponding to its solubility in pure SC CO2 under equivalent conditions. Under these conditions, the solubility of beta-carotene in triolein-modified CO2 increased by a factor of up to 4.0 in relation with its solubility in pure CO2 at comparable system temperature and pressure, reaching an uppermost value of 3.3 mu mol/mol at 333 K and 32 MPa. Unlike in the case of ethanol, where enhancements in solubility where relatively independent on system conditions, solubility enhancements using triolein as co-solvent increased markedly with system pressure, being larger than using (1.2 to 1.6)% mol ethanol at about (24 to 28) MPa, depending on system temperature. The increase in the solubility beta-carotene in SC CO2 as a result of using ethanol or triolein as co-solvent apparently does not depend on the increase in density associated with the dissolution of the co-solvent in CO2. Enhancements may be due to an increase in the polarizability of SC CO2, which possibly growths markedly as triolein dissolves in it when the system pressure becomes higher. (C) 2011 Elsevier Ltd. All rights reserved.
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    Solubility of carotenoid pigments (lycopene and astaxanthin) in supercritical carbon dioxide
    (ELSEVIER SCIENCE BV, 2006) de la Fuente, Juan C.; Oyarzun, Bernardo; Quezada, Nathalie; del Valle, Jose M.
    This contribution provides basic data for developing an extraction process for carotenoid compounds in terrestrial and marine plants with supercritical CO2 (SC-CO2). Specifically, the solubility (y(2), molar fraction) of lycopene and astaxanthin was measured in SC-CO2 as a function of temperature (313 K <= T <= 333 K) and pressure (10 MPa <= P <= 42 MPa). Experimental data were correlated using a density-based model valid for a solvent density above 330kg/m3. Based on this model and the best-fit model parameters, the solubility of lycopene in SC-CO2 at 313 K and 30 MPa (y(2) = 0.40 x 10(-6)) was within a wide range of experimental values for the solubility of beta-carotene in CO2 under same conditions (0.20 x 10(-6) <= y(2) <= 0.50 x 10-6). The interpolated solubility of astaxanthin in SC-CO2 at 313 K and 30 MPa was slightly smaller (y(2) = 0.19 x 10(-6)) than the one of lycopene, as expected for a slightly heavier and more polar solute. There was a larger increase in solubility of both lycopene and astaxanthin by increasing the temperature from 313 to 333 K at a constant pressure of 30 MPa (2.8-5.1 times) than by increasing the pressure from 30 to 50 MPa at a constant temperature of 313 K (1.3-1.6 times), which was consistent with the trend in literature for the solubility of beta-carotene in SC-CO2. (c) 2006 Elsevier B.V. All rights reserved.
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    Supercritical CO2 oilseed extraction in multi-vessel plants. 2. Effect of number and geometry of extractors on production cost
    (ELSEVIER SCIENCE BV, 2014) Nunez, Gonzalo A.; del Valle, Jose M.
    The objective of this work was to study production costs for the supercritical CO2 extraction of a pre-pressed oilseed (packed bed with 2-mm particles) in a 2-m(3) industrial multi-vessel plant operating at 40 degrees C and 30 MPa, using a fully predictive mass transfer model to simulate the process. We modified the inner diameter (473 <= D <= 65.6 cm) and number (n = 2, 3, or 4) of extraction vessels, and the mass flow rate of CO2 (Q = 3000 or 6000 kg/h), thus changing the aspect ratio of the extraction vessels (3 <= L/D <= 8), and superficial velocity (2.71 <= U <= 10.8 mm/s) and specific mass flow rate (6 <= q <= 24 kg/h per kg substrate) of CO2. Production cost decreased when increasing the mass flow rate of CO2 or the number of extraction vessels (or when increasing q). Production cost did not depend on the geometry of extraction vessel for a constant specific mass flow rate of CO2, but it decreased with a decreasing of the L/D ratio of the vessel for a constant superficial velocity of CO2. For any given plant, the contribution of fixed cost items (capital, labor) to the production cost increased with extraction time, unlike that of variable cost items (substrate, CO2, energy), which decreased. Thus, there was an optimal extraction time that minimized production cost for each plant. This work proposes an expression for capital cost of an industrial multi-vessel plant as a function of the mass flow rate of CO2 (which defines the cost of the solvent cycle of the plant), and the volume of the extraction vessels (which together with number of extraction vessels define the cost of extraction section of the plant), with a scaling factor of 0.48 for both items. Under optimal conditions, capital cost represented 30-40% of the production cost, but uncertainties in capital cost estimates (about +/- 50% using the proposed expression) may largely affect these estimates. The lowest production cost estimated in this work was USD 7.8/kg oil for the extraction of prepressed oilseed in a four-vessel plant using 6000 kg/h of CO2. The mass flow rate of CO2 and number of extraction vessels also affected annual productivity that was about 360 ton oil for the same plant operating 7200 h per year. Oil yields were above 90% for both three- and four-vessel plants. (C) 2014 Elsevier B.V. All rights reserved.
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    Supercritical CO2 extraction of aqueous suspensions of disrupted Haematococcus pluvialis cysts
    (2022) Aravena, Raul, I; del Valle, Jose M.; de la Fuente, Juan C.
    This contribution compares the supercritical (SC) CO2 extraction of astaxanthin from disrupted Haematococcus pluvialis cysts in either an aqueous suspension or packed bed of dry powder at 40 or 70 degrees C and 35-55 MPa. The initial stage of the process for aqueous suspensions consisted of a solubility-controlled removal of water that delays oleoresin extraction in comparison to the dry substrate. In addition, residual water in the partially dried suspension made oleoresin extraction slower than from the dry substrate. However, the presence of water in an aqueous suspension surprisingly made the oleoresin extraction more sensitive to temperature in comparison to dry powder, affecting the selectivity of the extraction for astaxanthin in a large extend.
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    Supercritical CO2 extraction of pinocembrin from Lippia origanoides distillation residues. 1. Multicomponent solubility and equilibrium partition
    (2022) Arias, Julian; Martinez, Jairo; Stashenko, Elena; del Valle, Jose M.; de la Fuente, Juan C.
    Steam-distilled oregano (Lippia origanoides) distillation process was analyzed and described as a model binary mixture. The most abundant identified and selected compounds were pinocembrin, a high-value flavonoid, as representative of the minor fraction, and octacosane, a cuticular wax, of the major fraction. Thermodynamic solubility of the solid multicomponent mixture in supercritical CO2 was measured at 313 K and 323 K, and pressures from 8.6 to 32.1 MPa, using a dynamic-analytical method with on-line HPLC analysis. The molar fraction of pinocembrin in CO2-rich phase was assessed from 4.8.10(-6) to 33.10(-6) mol/mol. The solid + fluid equilibrium for the ternary model system was modeled with the Peng-Robinson equation of state and the classical van der Waals mixing rules. Extraction experiments of the solid multicomponent mixture with supercritical CO2 modified with 2-9% w/w ethanol, were carried out in a one-pass pilot scale apparatus at 308 K, 323 K and 338 K, and pressures of 18 MPa, 26 MPa, and 34 MPa. For each sample, the pinocembrin content was assessed. The extraction curves for oleoresin and pinocembrin were represented with empirical models from which the oleoresin partition constants were estimated, that were in range from 0.03 to 0.13 kg/kg substrate/CO2 depending on extraction conditions. However, the partition constant remained virtually invariant, independently of changes in the extraction temperature and pressure conditions, and the ethanol content in CO2, with an average value of 0.08 kg/kg substrate/CO2. These results will facilitate using a simplified mass transfer model to describe oleoresin extraction from steam-distilled L. origanoides.
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    Supercritical CO2 extraction of pinocembrin from Lippia origanoides distillation residues. 2. Mathematical modeling of mass transfer kinetics as a function of substrate pretreatment
    (2022) Arias, Julian; Martinez, Jairo; Stashenko, Elena; del Valle, Jose M.; Nunez, Gonzalo A.
    Lippia origanoides and L. graveolens are natural sources of essential oils and compounds with bioactivity (e.g., flavonoids). The objective of this work was to model the extraction of L. graveolens and carvacrol-, thymol-, and phellandrene-rich chemotypes of L. origanoides using ethanol-modified supercritical CO2 as the solvent using the Broken-and-Intact Cells (BIC) and Shrinking Core (SC) models. We studied the effects of the substrate and its pretreatment (grinding versus pelletization) and extraction conditions on extraction rate and yield. Model parameters for the BIC (fraction of broken cells, partition coefficient, and microstructural factor) and SC (micro structural factor) models were best-fitted to experimental cumulative extraction curves. Pelletizing favored rupture of inner cells, but made part of the oleoresin unavailable for extraction, partially due to thermal damage. SC was appropriate only for pelletized substrate, because it hypothesizes an interconnected porous space filled with condensed oleoresin, whereas that BIC was much better for the extraction of ground substrates.
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    Time Fractionation of Minor Lipids from Cold-Pressed Rapeseed Cake Using Supercritical CO2
    (WILEY, 2012) Uquiche, Edgar; Fica, Ximena; Salazar, Katherine; del Valle, Jose M.
    This work explored the possibility of using supercritical carbon dioxide (SC-CO2) to achieve fractionation of pre-pressed rapeseed (Brassica napus) cake oil at 30-50 MPa, at 40 or 80 degrees C, and increase the concentration of minor lipids (sterols, tocopherols, carotenoids) in the oil. Minor lipids are partially responsible for desirable antioxidant effects that protect against degradation and impart functional value to the oil. The weight and concentration of minor lipids in oil fractions collected during the first 60 min were analyzed. Cumulative oil yield increased with pressure, and with temperature at >= 40 MPa, but was lower at 80 degrees C than at 40 degrees C when working at pressure <= 35 MPa. Differences in solubility between the oil and minor lipids explained fractionation effects that were small for tocopherols. Unlike tocopherols, which are more soluble in SC-CO2 than the oil, sterols and carotenoids are less soluble than the oil, and their concentration increased in the later stages of extraction, particularly at >= 40 MPa, when there was not enough oil to saturate the CO2 phase. Because of the fractionating effects on rapeseed oil composition, there was an increase in the antioxidant activity of the oil in the second half as compared to the first half of the extraction. Consequently, this study suggests that SC-CO2 extraction could be used to isolate vegetable oil fractions with increased functional value.