نتایج جستجو برای: supercritical
تعداد نتایج: 10552 فیلتر نتایج به سال:
Wheat germ oil was obtained by mechanical pressing using a small-scale screw press and by supercritical extraction in a pilot plant. With this last method, different pressures and temperatures were tested and the tocopherol concentration in the extract was monitored during extraction. Then supercritical extracted oil as well as commercial pressed oil were deacidified in a countercurrent column ...
Extraction and chromatographic separation of fat-soluble vitamins is a challenging task, due to the sensitivity of these compounds towards light, oxygen, heat and pH. In light of this, supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) are attractive techniques as they function at considerably milder conditions than conventional solvent-based analytical techniques...
Conversion of glycerol from biodiesel production to glycerol carbonate was studied by esterification with dimethyl carbonate in a non-catalytic supercritical condition. It was found that in a non-catalytic supercritical condition, glycerol at higher purity gave higher yield of glycerol carbonate at 98 wt% after reaction at 300 °C/20-40 MPa/15 min. The yield of glycerol carbonate was observed to...
The purpose of this evaluation was to provide an objective evaluation of the use of supercritical carbon dioxide (CO,) as an alternative technology for spray applied in wood finishing processes using reduced solvent formulations. Union Carbide has pioneered this technology under the UNICARBTM trademark. In the UNICARBTM process, the solvent-like properties of supercritical CO, are employed to r...
Supercritical fluid extraction was used to extract the alkaloid N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl]pyrrolidine from leaves of Piper amalago L. A three-level orthogonal array design matrix, OAD OA9(34), was used for optimization of the parameters of supercritical extraction of the alkaloid, employing supercritical carbon dioxide: extraction time (20, 40, and 60 min), temper...
BACKGROUND Caryocar brasiliense Camb (Pequi) is a typical Brazilian Cerrado fruit tree. Its fruit is used as a vitamin source for culinary purposes and as a source of oil for the manufacture of cosmetics. C. brasiliense supercritical CO2 extracts exhibit antimicrobial activity against the bacteria Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and also possess antioxidant a...
We examine the structure of the hydrated Ti(IV) complex under both ambient and supercritical conditions using first-principles molecular dynamics. We find that an unanticipated fivefold coordination of Ti(IV) is favoured under ambient conditions, with rapid interconversions between square pyramidal and trigonal bipyramidal structures. At supercritical conditions the Ti coordination increases fr...
The use of supercritical fluids as chromatographic mobile phases provides rapid separations with high efficiency, favoring their use in enantioselective separations. Supercritical fluid technology (SFC) is a versatile tool in the purification, enantioseparation and large-scale production of enantiomers of pharmaceuticals over comparable liquid chromatographic methods and is gaining popularity i...
The paper aims to study the whole process mathematical model for a supercritical coal-fired power plant. The modeling procedure is based on thermodynamic and engineering principles and the previously published literatures. Model unknown parameters are identified using Genetic Algorithms (GAs) with 600MW supercritical power plant on-site measurement data. The identified parameters are verified w...
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