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Topic: Supercritical

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	LGCG Supercritical Fluids
		Supercritical fluids can be used as solvents, which enable reactions to be carried out without the use of harsh reagents or other toxic solvents.
		It is possible to reuse the supercritical solvent due to excellent post reaction recovery.
		In the supercritical state the solvents were found to have polarisability/polarity parameters that are comparable to diethyl ether under ambient conditions and close to the critical temperature the ratio of local to bulk density was found to be independent of the solvent studied.
	www.le.ac.uk /ch/greenchem/supercritical_fluids.html (1046 words)

	Supercritical Fluids – Fundamentals and Applications
		Supercritical fluids such as water and carbon dioxide are substances that are compatible with the earth's environment.
		Supercritical fluids are used as the extracting solvents for the removal of polyaromatic hydrocarbons from soil.
		Supercritical carbon dioxide extraction is used as a replacement for hexane in extracting soybean-oil and has been tested for extraction from corn, sunflower and peanuts.
	chemeng.iisc.ernet.in /giridhar/rect.html (3334 words)

	Supercritical fluid - Wikipedia, the free encyclopedia
		Carbon dioxide and water are the most commonly used supercritical fluids.
		In a practical sense, the area of interest in supercritical fluids for processing and separation purposes is limited to temperatures in the vicinity of the critical point, where large gradients in the physical properties are observed.
		In the case of supercritical carbon dioxide, the viscosity is in the range of 20–100 µPa·s (0.02-0.1 cP), where liquids have viscosities of approximately 500–1000 µPa·s (0.5-1.0 cP) and gases approximately 10 µPa·s (0.01 cP), respectively.
	en.wikipedia.org /wiki/Supercritical_fluid (693 words)

	Dyeing in supercritical carbon dioxide
		A German patent was granted in 1994 for a process in which a dye, free of additives is dissolved in a supercritical fluid and the substrate to be dyed is suffused with this.
		Table II compare a number of properties of gas, liquid and supercritical fluid which significantly affect dyeing processes: As will be noted from table II, the density and thus the dissolvability of the supercritical fluid is more or less similar to relative properties of liquids,whereas the viscosity is similar to that of a gas.
		Spectrophotometric measurements in a supercritical medium during stepwise reduction of the density have shown that short-time over saturated solutions will be formed which accelerate the absorption of the dyestuff molecules lack other condensation nuclei during the gaseous phase.
	www.geocities.com /nitiz_sood/dye.html (2799 words)

	Supercritical Antioxidants
		Supercritical antioxidants, from New Chapter, is a blend of 7 antioxidant herbs/spices.
		Supercritical extraction uses pressurized carbon dioxide to extract both the water-soluble and fat-soluble components of the herb or spice — resulting in a more “holistic” or complete extract.
		Supercritical Antioxidants sells for $25.95 for a one-month supply (60 softgel capsules) — which represents a very reasonable daily cost of about 86 cents for a very well-balanced blend of standardized herbs that all have promising research in the area of cancer prevention and treatment.
	www.supplementwatch.com /reviews/doc.asp?DocId=2381 (880 words)

	A.G.Kalinichev: Supercritical fluids
		Supercritical fluids are highly compressed gases at temperatures and pressures above the critical point.
		Due to the high compressibility of supercritical fluids, small changes in pressure can produce substantial changes in density which, in turn, affect diffusivity, viscosity, dielectric, and solvation properties of these fluids, thus dramatically influencing the kinetics and mechanisms of chemical reactions.
		A.G.Kalinichev (1998) Supercritical water as a medium for a new generation of environmentally friendly and energy efficient technologies of the XXI century.
	www.geology.uiuc.edu /~kalinich/scf.html (905 words)

	Method and apparatus to remove additives and contaminants from a supercritical processing solution - Patent 6805801
		However, such methods require large amounts of solvent because the supercritical solution containing the precursor, reactant, cleaning agent, or contaminant must either be completely displaced from the reactor or diluted to a level sufficient to avoid precipitation or deposition of the used or unwanted chemicals on the wafer.
		Near supercritical fluids or solutions exist when the temperature and pressure of a solution are both greater than 80% of their critical point, but the solution is not yet in the supercritical phase.
		That is, a supercritical solution (containing one or more solutes) enters recirculation loop 120, at least a portion of the one or more solutes are removed from the supercritical solution by contaminant removal mechanism 122, and then a purified solvent exits the contaminant removal system and reenters process vessel 106.
	www.freepatentsonline.com /6805801.html (7627 words)

	Frequently Asked Questions about Supercritical Fluid Technologies
		Supercritical carbon dioxide is also desirable for extraction of compounds that are sensitive to extreme conditions because it has a relatively low critical temperature (31°C).
		Supercritical fluids are especially attractive as reaction medium for diffusion-controlled reactions involving gaseous reagents such as hydrogen or oxygen.
		An example of using supercritical fluids as a reaction medium is the hydrogenation of pharmaceuticals to promote enantio selective hydrogenation to favor a cis or trans version of a molecule during hydrogenation.
	www.supercriticalfluids.com /faqs.htm (2018 words)

	CHP - Supercritical Fluid Extraction (Site not responding. Last check: 2007-10-23)
		Supercritical fluids can be used to extract analytes from samples.
		The main advantages of using supercritical fluids for extractions is that they are inexpensive, contaminant free, and less costly to dispose safely than organic solvents.
		For these reasons supercritical fluid CO is the reagent used to extract caffeine from coffee.
	www.chem.vt.edu /chem-ed/sep/sf/sfe.html (271 words)

	Supercritical Fluids - Product Lines > Specialty Gases & Chemicals > Analytical & Environmental \| Linde ... (Site not responding. Last check: 2007-10-23)
		Supercritical fluids have densities, viscosities and other properties that are intermediate between those of the substance in its gaseous and in its liquid state.
		Supercritical fluid chromatography (SFC) is a hybrid of gas and liquid chromatography.
		Supercritical fluid extraction (SFE) is based on the principle that solubilities in a supercritical fluid increase dramatically with increasing density, and that different solutes have different solubilities at the same conditions.
	www.us.lindegas.com /international/web/lg/us/likelgus30.nsf/docbyalias/nav_spec_super (903 words)

	Supercritical fluids: realising potential
		Supercritical fluids can be difficult to handle, but they have found numerous roles in experimental and commercial chemistry.
		They reported that the precipitate from supercritical fluids ‘is crystalline, and may be brought down as a “snow” in the gas, or on the glass as a “frost”’.
		Chemists continued to experiment with supercritical fluids for almost a century, although they remained something of a curiosity until the 1970s, when rising energy costs led chemists to consider supercritical fluids as a cheaper alternative to liquid extraction and distillation.
	www.rsc.org /chemistryworld/Issues/2005/February/supercriticalfluids.asp (2006 words)

	Supercritical Fluid Chromatography (SFC)
		In Supercritical Fluid Chromatography (SFC), the sample is carried through a separating column by a supercritical fluid (typically carbon dioxide) where the mixture is divided into unique bands based on the amount of interaction between the individual analytes and the stationary phase in the coumn.
		Supercritical fluid chromatography can most easily be described as an adaptation of either high performance liquid chromatography (HPLC) or gas chromatography (GC) where the major modification is the replacement of either the liquid or gas mobile phase with a supercritical fluid mobile phase.
		It is maintained supercritical as it passes through the column and into the detector by a pressure restrictor placed either after the detector or at the end of the column.
	ewr.cee.vt.edu /environmental/teach/smprimer/sfc/sfc.html (1123 words)

	Preliminary Evaluation of Supercritical Water Gasification of Biomass
		At supercritical conditions, a fluid does not meet the definition of a liquid because it can't be made to boil by decreasing the pressure at constant temperature.
		Under supercritical conditions, solid solubility often is enhanced greatly with respect to solubility in the gas or liquid solvent.
		Supercritical water in particular has the ability to dissolve materials not normally soluble in liquid water or steam and also seems to promote some types of chemical reactions.
	www.energy.iastate.edu /renewable/biomass/cs-water.html (903 words)

	Supercritical Airfoil
		The unique design of the supercritical wing reduces the effect of shock waves on the upper surface near Mach 1, which in turn reduces drag.
		Whitcomb was already famous for developing the "Area Rule" of supersonic flight which won him the Collier Trophy and which resulted in some fighters of the mid 1950s having a pinch midway along their fuselage, like an hourglass.
		By the mid-1970s, supercritical wings were being incorporated into a whole range of aircraft, from subsonic transports to business jets.
	www.centennialofflight.gov /essay/Evolution_of_Technology/supercritical/Tech12.htm (1176 words)

	SF News - Aug. 1, 1996 - Supercritical Water (Site not responding. Last check: 2007-10-23)
		To create supercritical water, Percival employs the same principle that applies to a pressure cooker in the kitchen: pressure increases when normal water is heated in a closed vessel.
		Despite the potential practical benefits of supercritical water, he argues vigorously that his research is driven only by curiosity and the need to better understand this unusual substance.
		The cylinder containing supercritical water has to be very strong to withstand the high pressures inside it, but it also acts as a barrier to light beams and other probing techniques.
	www.sfu.ca /mediapr/sfnews/1996/Aug1/superh20.html (581 words)

	Supercritical Airfoils (Site not responding. Last check: 2007-10-23)
		Supercritical airfoils are designed to delay and reduce the transonic drag rise, due to both strong normal shock and shock-induced boundary layer separation.
		As compared with a conventional airfoil a supercritical airfoil has reduced amount of camber, an increased leading edge radius, small surface curvature on the suction side, and a concavity in the rear part of the pressure side.
		Design of supercritical airfoils has been made easier in recent years, due to the progress in theoretical methods for inverse design at transonic speeds.
	www.aerodyn.org /HighSpeed/supercritical.html (206 words)

	SUPERCRITICAL CO2 EXTRACTION
		Although a supercritical fluid (SCF) is at single phase, it exhibits properties of both a liquid and a gas.
		Fluids in their supercritical states, having a high rate of absorbtion, are widely used in organic contaminant extraction from soil, water and precipitates.
		Supercritical CO2's uses continue to be explored and expanded due to its many benefits.
	www.calpoly.edu /~ceenve/enve/supercrit.html (1487 words)

	New Chapter - Supercritical Extraction
		New Chapter’s supercritical extracts are super potent, super pure, and broad spectrum with a representative composition very near to the botanical raw material.
		The supercritical process, then, uses a harmless, natural gas, heats it to some temperature over 31 degrees C (the lower the better to avoid any temperature stress), and the gas is then highly compressed.
		Our Supercritical Therapy™ line of products is patent-pending and often uses both supercritical and other extraction processes on the same herb, which we call a “Dual Extract.” Our Supercrital Therapy™ products thus represent not only the finest formulas and ingredients, but also extraction methodologies based on the unsurpassed values of a supercritical extract.
	www.new-chapter.com /research/supercritical.html (1474 words)

	Critical mass - Wikipedia, the free encyclopedia
		Supercritical redirects here; for supercritical fluid, see supercritical fluid.
		A re-creation of a 1945 criticality accident to measure the radiation produced when an extra block was added, making the mass supercritical.
		The critical mass of fissile material is the amount needed for a sustained nuclear chain reaction.
	en.wikipedia.org /wiki/Supercritical (1414 words)

	Untitled
		They are called "supercritical fluids" as opposed to liquids or gases, because the latter terms lose their meaning under these conditions.
		Under supercritical conditions, it has a density similar to that of a liquid (roughly half that of water), but its mobility and its ability to flow are similar to those of a gas.
		It has been discovered that caffeine is very soluble in supercritical carbon dioxide at about 300 atmospheres pressure and 40 to 50 degrees C. In a process being used since 1978 in West Germany, the coffee beans are extracted with the supercritical carbon dioxide.
	www.physics.uoguelph.ca /summer/scor/articles/scor110.htm (697 words)

	CHP - Supercritical Fluid Chromatography (Site not responding. Last check: 2007-10-23)
		Supercritical fluids can be used as the mobile phase to separate analytes with chromatographic columns.
		As in supercritical-fluid extraction (SFE), supercritical fluids can have solvating powers similar to organic solvents, but with higher diffusivities, lower viscosity, and lower surface tension.
		A supercritical fluid chromatograph consists of a gas supply, usually CO, a pump, the column in a thermostat-controlled oven, a restrictor to maintain the high pressure in the column, and a detector.
	www.chem.vt.edu /chem-ed/sep/sf/sfc.html (199 words)

	Supercritical Fluid Extraction (Site not responding. Last check: 2007-10-23)
		Supercritical fluids can be used to extract analytes from samples.
		The main advantages of using supercritical fluids for extractions is that they are inexpensive, contaminant free, and less costly to dispose safely than organic solvents.
		For these reasons supercritical fluid CO is the reagent used to extract caffeine from coffee.
	www.chemistry.adelaide.edu.au /external/soc-rel/content/sfe.htm (261 words)

	A Technology now being Deployed in Developing Countries (Site not responding. Last check: 2007-10-23)
		"supercritical" is a thermodynamic expression describing the state of a substance where there is no clear distinction between the liquid and the gaseous phase (i.e.
		In supercritical cycles there is a trend to increase the temperature of the reheat steam that enters the IP turbine section in order to raise the cycle efficiency.
		supercritical steam conditions, single reheat, operation in sliding-pressure mode with main steam conditions at 638 kg/s, 25,3 MPa, 544 °C and reheat steam conditions at 5,2 MPa, 562 °C. Seven-stage regenerative feed heating with a final temperature of 270 °C and turbine-driven boiler feed pump.
	www.worldbank.org /html/fpd/em/supercritical/supercritical.htm (2469 words)

	Supercritical Carbon-dioxide Cleaning Technology Review
		Supercritical fluids are by definition at a temperature and pressure greater than or equal to the critical temperature and pressure of the fluid.
		Supercritical fluids are able to spread out along a surface more easily than a true liquid because they have lower surface tensions than liquids.
		At the same time, a supercritical fluid maintains a liquid’s ability to dissolve substances that are soluble in the compound, which a gas cannot do.
	www.pprc.org /pubs/techreviews/co2/co2intro.html (637 words)

	Supercritical and Subcritical Extraction Technologies Center
		The EERC is a world leader in understanding the chemistry of water and CO under pressurized and heated (supercritical and subcritical) conditions for the extraction and separation of organic compounds that are not efficiently extracted without the use of hazardous organic solvents.
		Supercritical fluids have lower viscosities and higher solute diffusivities than liquid solvents, thus enhancing mass transfer.
		Supercritical water (temperature >374ºC, pressure >221 atm) is an excellent solvent for such pollutants but is extremely corrosive.
	www.undeerc.org /centersofexcellence/extraction.asp (534 words)

	Introduction to Supercritical Fluids
		Supercritical fluids are highly compressed gases which combine properties of gases and liquids in an intriguing manner.
		In addition, supercritical fluids can lead to reactions which are difficult or even impossible to achieve in conventional solvents.
		The definition of a supercritical fluid usually begins with a phase diagram, which defines the critical temperature and pressure of a substance.
	www.nottingham.ac.uk /supercritical/scintro.html (344 words)

	Use of supercritical fluids as environmentally benign solvents (Site not responding. Last check: 2007-10-23)
		Supercritical fluids, especially carbon dioxide and water, are viable replacement solvents for a variety of hazardous organic solvents.
		In fact, supercritical CO is used commercially for the decaffeination of coffee and tea and the extraction of a wide variety of natural oils, spices, flavors and fragrances.
		Recently, it has been shown that supercritical CO can be used with chelating agents to replace organic solvents for 1) the extraction of uranium from aqueous solutions produced in the processing of the ore and 2) the removal of heavy metals from soils and sludges.
	www.nd.edu /~enviro/supercritical.html (413 words)

	Supercritical dry: Page 1 of 1
		The supercritical release system dries wafers or dies after wet processing (such as release) without any surface tension (thus preventing stiction).
		The supercritical CO2 has extremely low surface tension, and as a result does not pull structures down as it transitions from liquid to gas.
		It is also an excellent cleaning fluid as the supercritical state retains the ability of liquid CO2 to dissolve organic compounds and oils, while the lowered surface tension makes it easier for the fluid to penetrate complex geometries and small cracks.
	www.mems-exchange.org /catalog/supercritical_dry (117 words)

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