<s docid="FBIS4-45803" num="16"> Dangerous Organic Solvents and Break Down Harmful Substances"] [Text] VDI-N, Duesseldorf, 6 May 94 - Nature possesses water and carbon dioxide in almost unlimited amounts.</s>

<s docid="FBIS4-45803" num="18"> In the "supercritical" state, for example, they can replace solvents that are harmful to the environment and can break down extremely stubborn ecological poisons.</s>

<s docid="FBIS4-45803" num="19"> Even chemically stable harmful substances can be broken down into CO[.sub]2[/] and water.</s>

<s docid="FBIS4-45803" num="23"> Dr. Helmut Schmieder of the Institute for Hot Chemistry at the Nuclear Research Center (KFZ) in Karlsruhe explained: "Water becomes a universal solvent for organic compounds under such conditions".</s>

<s docid="FBIS4-45803" num="26"> The best known such process introduced throughout the world is the removal of caffeine by means of supercritical carbon dioxide.</s>

<s docid="FBIS4-45803" num="28"> Carbon dioxide enjoys the greatest advantage as a supercritical extracting agent by virtue of the fact that it already achieves the solvent properties of a fluid at a temperature of 31ëC and a pressure of 74 bar.</s>

<s docid="FBIS4-45803" num="30"> In this way, the fat content of foods sold as dietary aids is reduced.</s>

<s docid="FBIS4-45803" num="31"> These processes are used to remove up to 80% of the cholesterol from powdered eggs and to derive aromatic substances from herbs.</s>

<s docid="FBIS4-45803" num="32"> The pharmaceutical industry is currently testing a supercritical carbon dioxide extraction process to purify vitamin E.</s>

<s docid="FBIS4-45803" num="34"> Carbon dioxide is nontoxic as a solvent, and it can be easily separated again from the dissolved substances after the reaction by means of "relaxation".</s>

<s docid="FBIS4-45803" num="35"> These supercritical processes are being increasingly used to separate organic toxins or oils out of sewage and contaminated solids.</s>

<s docid="FBIS4-45803" num="36"> In laboratory tests researchers in the Nuclear Research Center have now succeeded in almost completely separating the grinding oil from the sludges, which build up during glass processing, from the rubbed-off glass powder.</s>

<s docid="FBIS4-45803" num="41"> Reactions in supercritical water offer a new alternative for the destruction of highly toxic waste materials.</s>

<s docid="FBIS4-45803" num="43"> It not only becomes a good solvent for organic harmful substances, but is also mixes thoroughly with the air or oxygen.</s>

<s docid="FBIS4-45803" num="45"> Several laboratories in Germany and the United States are now studying "supercritical oxidation" as a means of disposing of harmful substances.</s>

<s docid="FBIS4-45803" num="51"> While in the subcritical state in wet oxidation the harmful substances are only partially decomposed, in the supercritical process up to 98% of stubborn waste materials like polychlorinated biphenyls (PCB), explosive materials, and chemical agents decompose.</s>

<s docid="FBIS4-45803" num="63"> Professor Michael Modell of Framingham, Massachusetts, believes that sewage sludges are an ideal object for supercritical water oxidation.</s>

<s docid="FBIS4-45803" num="68"> The attempt to clean heavily contaminated soil by means of supercritical water is being tackled by Professor Gustav Brunner in Hamburg-Harburg.</s>

<s docid="FR940318-0-00173" num="17"> Supercritical fluid cleaning, plasma cleaning, UV-ozone cleaning are all acceptable as substitutes for CFC-113 and MCF in electronics cleaning.</s>

<s docid="FR940318-0-00173" num="42"> Supercritical fluid cleaning, plasma cleaning, UV-ozone cleaning are all acceptable as substitutes for CFC-113 and MCF in precision cleaning.</s>

<s docid="FT932-7115" num="27"> The steam is said to be 'supercritical' above pressures of 221.2bar and temperatures of 5400C and higher.</s>

<s docid="FT932-7115" num="28"> Beyond this threshold, the transition from water to steam is continuous and the steam becomes a much more efficient carrier of heat.</s>

<s docid="FT932-7115" num="29"> The effect of such developments is to increase the thermal efficiency - the amount of energy produced per unit of fuel burnt - from the high 30s to the mid40s in percentage terms.</s>

<s docid="FT932-7115" num="31"> In the US, GE has developed what it calls an ultrasupercritical steam turbine, suitable for conditions of 300 bar and about 5950C, as part of a project funded by the Electric Power Research Institute.</s>

<s docid="FT932-7115" num="32"> According to GE, the design, in conjunction with an advanced boiler design, can deliver higher efficiency and reduced emissions per KW produced than turbines and plants employing conventional subcritical and supercritical steam cycles.</s>

<s docid="FR940318-0-00170" num="11"> Supercritical fluid cleaning, plasma cleaning and UV-ozone cleaning are all three high-technology methods of cleaning parts.</s>

<s docid="FR940318-0-00170" num="12"> These substitutes are mostly of interest for cleaning electronic parts or for precision cleaning, although supercritical carbon dioxide is being investigated for metal cleaning applications as well.</s>

<s docid="FBIS4-44747" num="21"> This new technique makes use of a supercritical fluid and is characterized as "supercritical drying".</s>

<s docid="FBIS4-44747" num="22"> It results in the ability to remove the fluid used to create the pores in the supercritical state without being able, in the process, to result in the development of addition-reaction films by the fluid with the silicon.</s>

<s docid="FBIS4-44747" num="23"> Additionally, no shrinkage phenomena surface, so that the size and structure of the pores remain fully intact.</s>

<s docid="FBIS4-44747" num="27"> Porous silicon is especially advantageous since it is considerably cheaper to produce than film-like gallium arsenide structures that have been used until now for experimental optoelectronic circuits.</s>

<s docid="FBIS4-66450" num="24"> Unlike ordinary water, supercritical water can break down plastics by being readily ionizable and miscible with oil.</s>

<s docid="FBIS4-66450" num="29"> The new ``hydrothermal reaction'' technology is said to be also capable of decomposing other plastic materials, such as polyester and polystyrene.</s>

<s docid="FBIS4-66450" num="30"> The reaction produces only oil and water, but essentially no harmful by-products.</s>

<s docid="FBIS4-66450" num="31"> Therefore, the technology is free of environmental problems, and the water can be re-used repeatedly in the process.</s>

<s docid="FT943-4354" num="6"> Scientists at the University of St Andrews have developed a process, called supercritical drying, to treat wooden objects after they are unearthed from an archaeological excavation.</s>

<s docid="FT943-4354" num="7"> It involves soaking the wood in methanol to replace the water, after which the wood is placed in a chamber containing carbon dioxide in the form of dry ice.</s>

<s docid="FT943-4354" num="8"> The methanol is then dissolved out of the wood by warming the carbon dioxide to the point when it becomes a 'supercritical fluid'.</s>

<s docid="FT943-4354" num="9"> In this state, the carbon dioxide is a high pressure gas, which has the advantage that the wood is not subjected to drying stresses when it is removed.</s>

<s docid="FT943-4354" num="10"> The university believes this system is an advance on conventional drying methods, which involve impregnating the wood with polyethylene glycol.</s>

<s docid="FR940318-0-00172" num="14"> Supercritical carbon dioxide is acceptable as a substitute for CFC-113 and MCF in the metals cleaning sector.</s>

<s docid="FR940318-0-00172" num="15"> The Agency's risk screen did not identify any environmental effects with significant concerns for this substitute.</s>

<s docid="FBIS4-44741" num="17"> [Text] Frankfurt--By means of supercritical liquid extraction, British scientists have extracted a highly porous form of silicon which emits visible light.</s>

<s docid="FBIS4-44741" num="18"> The aerocrystals are stable and should therefore be suitable as material for optical electronics.</s>

<s docid="FBIS4-44730" num="37"> An extraction and cleanup process using supercritical CO2 is under study.</s>

<s docid="FBIS4-44730" num="38"> The technique will enable oil companies to send drilling waste from which all traces of hydrocarbons have been removed to the bottom of the ocean.</s>

<s docid="FR940721-2-00028" num="11"> SUPPLEMENTARY INFORMATION: The objective of the project is continue tests to evaluate the supercritical water oxidation (SCWO) pilot plant developed under Cooperative Agreement DE-FC07-88ID12711.</s>

<s docid="FR940721-2-00028" num="12"> The pilot plant configuration was developed to treat corrosive wastes and waste with high solids content.</s>

<s docid="FR940721-2-00028" num="15"> DOE and commercial implementation of SCWO technology will reduce the volume of hazardous and mixed waste currently stored and generated in the United States.</s>

<s docid="FR940721-2-00028" num="16"> SCWO technology is recognized as a high potential alternative technology to incineration, providing cleaner effluents and with less institutional barriers than incineration.</s>

