Browsing by Author "del Valle, Jose M."
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- ItemCorrelation 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.
- ItemEffect 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.
- ItemMatrix 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
- ItemSolubilities 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.
- ItemSupercritical 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.