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CO2 Flow Rate (co2 + flow_rate)
Selected AbstractsMicronization of the officinal component baicalin by SEDS-PA processCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2007Wen Zhi He Abstract Application of micronizing technologies in processing Chinese herbal medicines is very important to improve the forms of prepared Chinese herbal medicines and promote their therapeutic efficacy. Baicalin, a major active component of the typical Chinese herb medicine Scullateria baicallensis Georgi, was micronized using the Solution Enhanced Dispersion by Supercritical fluids though Prefilming Atomization (SEDS-PA) process with the aim of evaluating the efficiency of applying supercritical fluid precipitation technologies in Chinese herb medicine. This study has shown that acicula or rod-like baicalin crystals with Particle Size (PS) of about 20×100 ,m were successfully micronized by the SEDS-PA process to long rod-like, twisted fiber-like or fibrous net-like microparticles with PS of 0.1-2.2 ,m in width within the range of experiments performed. It was found that a substantial reduction of baicalin microparticles' sizes could lead to a marked increase of adhesions among them and subsequent microparticles agglomeration. With the increase of supercritical CO2 flow rate and the decrease of solution concentration and solution flow rate, smaller and much more agglomerated microparticles were obtained. Increasing pressure led to formation of smaller microparticles. A larger tendency of particles agglomeration was produced at a higher temperature. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Supercritical carbon dioxide extraction of volatiles from Satureja fruticosa BéguinotFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2007J. A. Coelho Abstract Dried flowers and leaves of Satureja fruticosa Béguinot were submitted to supercritical CO2 extraction (SFE), followed by a two-stage fractional separation. The extraction was carried out at 40 °C in a flow apparatus, provided with a 1 l extraction vessel and two separators of 0.27 l each. Conditions of extraction, such as pressure, particle size of plant material and CO2 flow rate, were studied in order to assess their influence on the yield and composition of the volatiles. The best conditions of extraction were 90 bar pressure at 1.32 kg/h CO2 flow rate and a plant material particle size of 0.5 mm. The SFE volatiles obtained and the essential oil isolated by hydrodistillation (HD) were analysed and compared by GC and GC,MS. The oxygen-containing monoterpenes, pulegone (33,36% for SFE and 40,41% for HD), isomenthone (14,18% for SFE and 21% for HD), piperitenone (11,12% for SFE and 9,11% for HD) and piperitenone oxide (11,13% for SFE and 7,9% for HD) were the dominant components in all samples. Copyright © 2007 John Wiley & Sons, Ltd. [source] Analysis of supersaturation and nucleation in a moving solution droplet with flowing supercritical carbon dioxideJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2005Mamata Mukhopadhyay Abstract A supercritical antisolvent (SAS) process is employed for production of solid nanoparticles from atomized droplets of dilute solution in a flowing supercritical carbon dioxide (SC CO2) stream by attaining extremely high, very rapid, and uniform supersaturation. This is facilitated by a two-way mass transfer of CO2 and solvent, to and from the droplet respectively, rendering rapid reduction in equilibrium solubility of the solid solute in the ternary solution. The present work analyses the degree of supersaturation and nucleation kinetics in a single droplet of cholesterol solution in acetone during its flight in a flowing SC CO2 stream. Both temperature and composition are assumed to be uniform within the droplet, and their variations with time are calculated by balancing the heat and mass transfer fluxes to and from the droplet. The equilibrium solubility of cholesterol with CO2 dissolution has been predicted as being directly proportional to the Partial Molar Volume Fraction (PMVF) of acetone in the binary (CO2,acetone) system. The degree of supersaturation has been simulated up to the time required to attain almost zero cholesterol solubility in the droplet for evaluating the rate of nucleation and the size of the stable critical nuclei formed. The effects of process parameters have been analysed in the pressure range of 7.1,35.0 MPa, temperature range of 313,333 K, SC CO2 flow rate of 0.1136,1.136 mol s,1, the ratio of the volumetric flow rates of CO2 -to-solution in the range of 100,1000, and the initial mole fraction of cholesterol in acetone solution in the range of 0.0025,0.010. The results confirm an extremely high and rapid increase in degree of supersaturation, very high nucleation rates and stable critical nucleus diameter of the order of a nanometre. Copyright © 2005 Society of Chemical Industry [source] Supercritical CO2 extraction of accumulated capsidiol from biotic elicitor-activated Capsicum annuum L fruit tissuesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2005ur Salg Abstract This work investigates the supercritical CO2 extraction of capsidiol from pepper fruit tissues activated with Alternaria alternate (Fr) Keissler suspension culture as a biotic elicitor. Capsidiol production in the fruit tissue was markedly increased by the treatment with a biotic elicitor and reached its maximum level after 4 days of elicitation. The effects of separation parameters such as temperature, pressure, supercritical solvent flow rate, particle diameter and also initial capsidiol concentration were investigated on solubility, initial extraction rate and extraction yield. The optimal extraction conditions were obtained at the temperature of 40 °C, the pressure of 400 bar, the supercritical CO2 flow rate of 2 cm3 min,1, and the average particle diameter of 116 µm. The results showed that the ratio of the supercritical CO2 extraction yield to the organic solvent extraction yield was changed from 84 to 97 wt-% depending on the initial capsidiol concentration. Copyright © 2004 Society of Chemical Industry [source] Deodorization of Fish Sauce by Continuous-Flow Extraction with Microbubbles of Supercritical Carbon DioxideJOURNAL OF FOOD SCIENCE, Issue 8 2000M. Shimoda ABSTRACT: Volatiles were removed from fish sauce by continuous-flow extraction with microbubbles of supercritical carbon dioxide. The extraction was done at 35 °C and CO2/sample flow ratio of 0.14 and 0.29 under pressures of 10 to 30 MPa. After the treatment at a CO2/sample flow ratio, 0.29 at 10 MPa, remaining percentage ((the concentration in treated sample/that in untreated one) × 100) was 5.2% trimethylamine, 8.0% S-methyl ethanethioate, 30% dimethyldisulfide, 55 to 61% aliphatic aldehydes, and 25 to 42% carboxylic acids. The increase in CO2 flow rate improved the extraction efficiency significantly, but no effect of pressure was observed. The odor intensities of treated samples were between 1/4 and 1/8 of the untreated fish sauce. [source] Reactivation of spent Pd/AC catalyst by supercritical CO2 fluid extractionAICHE JOURNAL, Issue 9 2009Xiaoxin Zhang Abstract In this article, we reported a nondestructive and environmentally friendly method for the reactivation of a spent Pd/AC catalyst for the hydrogenation of benzoic acid by using supercritical CO2 (scCO2) fluid extraction. The effects of reactivation conditions, such as extraction temperature, pressure, CO2 flow rate, and time, on the activity of the reactivated Pd/AC catalyst, were presented. The catalyst was characterized by N2 physisorption, laser particle size analysis, and transmission electron spectroscopy, and the liquid extract was analyzed by GC-MS. It is found that scCO2 fluid extraction was very efficient in eliminating organic substances blocking the pores of the catalyst, while did not affect noticeably the granule size of the catalyst and the particle size of Pd. The reactivated Pd/AC catalyst regained more than 70% of the activity of the fresh 5.0 wt % Pd/AC catalyst, and has been successfully used in an industrial unit for the hydrogenation of benzoic acid. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Modeling of CO2 gasification of carbon for integration with solid oxide fuel cellsAICHE JOURNAL, Issue 4 2009Andrew C. Lee Abstract This modeling study focuses on gasification of carbon by CO2 in a minimally fluidized bed containing a solid oxide fuel cell (SOFC). Kinetic parameters for a five-step reaction mechanism characterizing the Boudouard reaction (C + CO2 , 2CO) were determined thermogravimetrically at 1 atm from 973 to 1273 K. Experimentally determined kinetic parameters are employed in a transport model that predicts velocities and gas concentration profiles established in the carbon bed as a consequence of convection, diffusion, and heterogeneous reaction. The model is used to simulate the effect of an imbedded SOFC, in contact with the carbon bed. Although the model does not assume particular I-V characteristics for the fuel cell, it indicates that current densities in the practical range of 100,1000 mA/cm2 can be supported. Results show that temperature strongly affects the current density, whereas CO2 flow rate has only a weak effect. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Enrichment of the thymoquinone content in volatile oil from Satureja montana using supercritical fluid extractionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2009Clara Grosso Abstract Supercritical fluid extraction (SFE) of the volatile oil from Satureja montana L. was performed under different conditions of pressure (90 and 100 bar), temperature (40 and 50°C), mean particle sizes (0.4, 0.6 and 0.8 mm) and CO2 flow rate (0.8, 1.1 and 1.3 kg/h) to understand the influence of these parameters on the composition and yield of this oil. The results were compared with those obtained for the essential oil isolated by hydrodistillation (HD). The volatile and the essential oil were analysed by GC and GC-MS. The main compounds are carvacrol (52.2,62.0% for HD vs. 41.7,64.5% for SFE), thymol (8.6,11.0% for HD vs. 6.0,11.3% for SFE), p -cymene (6.9,12.8% for HD vs. 6.0,17.8% for SFE), ,-terpinene (6.4,9.4% for HD vs. 2.3,6.0% for SFE) and ,-bisabolene (2.0,2.7% for HD vs. 2.2,3.5% for SFE). The major difference between SFE and HD was the relative amount of thymoquinone, an oxygenated monoterpene with important biological activities, which can be ten-fold higher in volatile oil (1.6,3.0 for SFE vs. 0.2% for HD). The morphology of the glandular trichomes of S. montana and the effect of the grinding process on them was also evaluated by SEM. [source] | ||||||||||