CO2 supercritical fluid

There is a potential for the commercial application of supercritical CO2 fluid extraction for fractionation of milk fat. However, the differences between the melting properties are not as pronounced as with melt crystallization, thereby limiting the application range of these fractions. Moreover, this process is more expensive than melt crystallization (Bhaskar et al., 1998). Nevertheless, niche applications could be developed if fractions rich... 

Process Fraction Fractionation by melt crystallization2 Supercritical CO2 fluid fractionation ... 

Adsorption equilibrium and adsorption dynamics on MSC were evaluated for each organics in supercritical CO2 fluid mixed with adsorbate by chromatographic measurement. The dependencies of adsorption equilibrium constants, K, and micropore diffiisivity, D, of toluene, benzene and m-xylene, on molarity of toluene with each parameters of temperature or pressure were obtained. It was found that the values of K and D for an organic substance depended on the amount adsorbed of other organics strongly. The state of the molecule could be observed by the molecular simulation. As for the amount adsorbed, the simulation is small, in comparison with the experiment. 

Supercritical CO2 is used to remove caffeine from coffee beans. First, the green coffee beans are soaked in water. The beans are then placed in the top of a column that is 70 ft high. Supercritical CO2 fluid at about 93 °C and 250 atm enters at the bottom of the column. 

The role of water as entrainer in the extraction of nicotine by supercritical CO2 fluid was studied by MD simulation. The following three systems were studied in detail ... 

Akao K, Okubo Y, Inoue Y, Sakurai M. Supercritical CO2 fluid extraction of crystal water from trehalose dihydrate. Efficient production of form II T ) phase. Carbohydr Res 2002 337 1729-1735. 

The Fermi resonance absorption bands, which obviously are IR active, increase in intensity with density of the supercritical CO2 fluid (11). This absorption becomes the limiting factor in selecting the pathlength for the flow-through analysis cell. In order to use this region of the IR spectrum, there must be enough analytical radiation remaining after the supercritical fluid absorbance to obtain adequate sensitivity for a particular application. 

INO Inomata, H., Honma, Y., Imahori, M., and Aral, K., Fundamental study of de-solventing polymer solutions with supercritical CO2, Fluid Phase Equil, 158-160, 857,1999. 

LEP Lepilleur, C., Beckman, E.J., Schonemann, H., and Krrrkonis, V.J., Effect of molecular architecture on the phase behavior of fluoroether-functional graft copolymers in supercritical CO2, Fluid Phase Equil, 134, 285, 1997. 

A versatile solvent, carbon dioxide is used as liquid CO2 or supercritical CO2 fluid (the states of CO2 most commonly used for solvent use). A gas is normally converted to a liquid state by increasing the pressure exerted upon it. However, if the substance is placed at a temperature above its critical temperature (31 C for CO2) and critical pressure (72.8 atm for CO2), a supercritical fluid is obtained. The of a substance is the temperature above which a distinct liquid phase of the substance cannot exist, regardless of the pressure applied. is the pressure at which a substance can no longer exist in gaseous state. In a supercritical liquid, the individual molecules are pressed so close together (due to high pressure) that they are almost in liquid state. Supercritical liquids have density close to that of the liquid state and viscosity close to that of gaseous state. 

Beier, M., Tsivintzelis, I., Grunwaldt, J., cf a/. (2011). Experimental determination and modeling of the phase behavior for the selective oxidation of benzyl alcohol in supercritical CO2, Fluid Phase Equilibr, 302, pp. 83-92. 

Edward Tayton, M. Purcell, A. Aarvold, J. O. Smith, S. Kalra, A. Briscoe, K. Shakesheff, S. M. Howdle, D. G. Dunlop, R. O. C. Oreffo, Supercritical CO2 fluid-foaming of polymers to increase porosity A method to improve the mechanical and biocompatibility characteristics for use as a potential alternative to allografts in impaction bone gUdiimgl, Acta Biomaterialia 8 (2012), p. 1918-1927. 

In the unfortunate events of water present in the supercritical CO2 fluid stream, CO2 hydrate and/or dry ice may briefly form as a result of Joule-Thomson cooling. The CO2 packing procedure may need to be revisited and modified to prevent the undesired circumstances from happening. 

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