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 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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    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 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 extraction of allicin from garlic flakes: Screening and kinetic studies
    (ELSEVIER SCIENCE BV, 2012) del Valle, Jose M.; Glatzel, Veronica; Martinez, Jose L.
    The nutraceutical industry is currently interested in obtaining garlic extracts using mild extraction processes to recover high levels of labile allicin. This work studied oleoresin yield and extraction selectivity for allicin in the supercritical CO2 extraction of freeze-dried aqueous garlic homogenate as a function of sample conditioning and process conditions. Agglomeration phenomena, which is responsible for substrate lumps in packed beds and flow channeling in the bed during extraction, was avoided by lowering sample moisture below 31 g kg(-1) water/substrate, and/or process temperature below 65 degrees C. Oleoresin yield increased slightly with extraction pressure (15-45 MPa) and dramatically with process temperature (35-65 degrees C), but the concentration of allicin in the extract decreased as the temperature increased. Thus, an optimal combination of intermediate temperature and pressure was selected that allowed reasonably large yields (>=-19 g kg(-1) oleoresin/substrate) and extraction selectivities (>= 75 mg kg(-1) allicin/oleoresin). Based on experimental results, a 4 h extraction process at 55 degrees C and 30 MPa using 55 kg kg(-1) CO2/substrate was recommended. Cumulative extraction plots for oleoresin and allicin were successfully adjusted using a linear driving force mass transfer model. (C) 2011 Elsevier Ltd. All rights reserved.
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    Supercritical CO2 oilseed extraction in multi-vessel plants. 1. Minimization of operational cost
    (ELSEVIER SCIENCE BV, 2014) del Valle, Jose M.; Nunez, Gonzalo A.; Aravena, Raul I.
    This work uses a fully predictive mass transfer model to simulate the supercritical CO2 extraction of vegetable oils from prepressed oilseeds in the 1-m(3) vessel of an industrial multi-vessel plant operating at 40 degrees C and 30 MPa with the purpose of minimizing the operational cost. The work analyses the effect of particle diameter (0.5, 1, 2, 3, and 4 mm), superficial CO2 velocity (2.76, 5.52, or 11.0 mm/s), and number of extraction vessels (2, 3, or 4) on optimal extraction time and minimal operational cost. Keeping other variables constants, cost diminishes as particle diameter decreases. Although the optimal superficial CO2 velocity increases as particle diameter decreases, in the case of small (<= 1 mm) particles, substrate fluidization may place an upper limit to the superficial velocity. Within the studied region, best superficial CO2 velocities are 11.0 mm/s for particles smaller than 1-2 mm, 2.76 mm/s for particles larger than 3-4 mm, and 5.52 mm/s for particles in between. Keeping other variables constant, the cost of extraction of medium-to-large (>= 2 mm) particles decreases as the number of extraction vessels increases, at the expense of an increase in extraction time. However, because of a sharp transition wave that develops when extracting small (<= 1 mm) particles that separates fully extracted (downstream) from virtually unextracted (upstream) substrate within extraction vessels, two-vessel plants are best for small particles. The lowest operational cost observed in this work was USD 4.08 kg(-1) oil for the extraction of 2-mm particles using 3.30 m(3)/h of CO2 (U=2.76 mm/s) in a four-vessel plant. (C) 2014 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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    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.