Pressurized solvent extraction

With liquid feed solutions, however, it is possible to work in a manner analogous to traditional solvent extraction. Pressurized columns can be of the packed-bed type or agitated by magnetic stirrers. Because of the efforts of pilot plant tests, much of the scale-up work has to be carried out in laboratory extractors. From solubility measurements, it is possible to determine parameters in thermodynamic models (e.g., equations of state), which can be used for the simulation of large-scale applications. 

Accelerated solvent extraction (pressurized fluid extraction) Semi-volatiles and non-volatile organics from soils, relatively dry sludges and solid wastes Extraction under pressure using small volumes of organic solvent... 

See also Chromatography Overview Principles. Dioxins. Extraction Solvent Extraction Principles Microwave-Assisted Solvent Extraction Pressurized Fluid Extraction. Food and Nutritional Analysis Oven/iew. Forensic Sciences Oven/iew. Gas Chromatography Overview. Lipids Oven/iew. Liquid Chromatography Overview. Pesticides. Pharmaceutical Analysis... 

Microwave-Assisted Solvent Extraction Pressurized Fluid Extraction Supercritical Fluid Extraction Solid-Phase Extraction Solid-Phase Microextraction. Gas Chromatography Overview, Mass Spectrometry Environmental Applications. Immunoassays Overview. Liquid Chromatography Overview Reversed Phase Size-Exclusion Liquid Chromatography-Mass Spectrometry. Pesticides. Supercritical Fluid Chromatography Overview Applications. Thin-Layer Chromatography Overview. Water Analysis Organic Compounds. 

Brown coals yield, on solvent extraction, 10—15% of a material that contains 60—90% light yellow or brown waxy substances. The remainder is a mixture of deep brown resinous and asphaltic substances. The yield may be increased by increasing the pressure during extraction, but this also adds dark colored dispersion products, and the resultant brown coal caimot be briquetted. 

The chain-growth catalyst is prepared by dissolving two moles of nickel chloride per mole of bidentate ligand (BDL) (diphenylphosphinobenzoic acid in 1,4-butanediol). The mixture is pressurized with ethylene to 8.8 MPa (87 atm) at 40°C. Boron hydride, probably in the form of sodium borohydride, is added at a molar ratio of two borohydrides per one atom of nickel. The nickel concentration is 0.001—0.005%. The 1,4-butanediol is used to solvent-extract the nickel catalyst after the reaction. 

The mixture is kept for 3 hours at 105°C after the oxide addition is complete. By this time, the pressure should become constant. The mixture is then cooled to 50°C and discharged into a nitrogen-filled botde. The catalyst is removed by absorbent (magnesium siUcate) treatment followed by filtration or solvent extraction with hexane. In the laboratory, solvent extraction is convenient and effective, since polyethers with a molecular weight above about 700 are insoluble in water. Equal volumes of polyether, water, and hexane are combined and shaken in a separatory funnel. The top layer (polyether and hexane) is stripped free of hexane and residual water. The hydroxyl number, water, unsaturation value, and residual catalyst are determined by standard titration methods. 

Analytical Techniques. Sorbic acid and potassium sorbate are assayed titrimetricaHy (51). The quantitative analysis of sorbic acid in food or beverages, which may require solvent extraction or steam distillation (52,53), employs various techniques. The two classical methods are both spectrophotometric (54—56). In the ultraviolet method, the prepared sample is acidified and the sorbic acid is measured at 250 260 nm. In the colorimetric method, the sorbic acid in the prepared sample is oxidized and then reacts with thiobarbituric acid the complex is measured at - 530 nm. Chromatographic techniques are also used for the analysis of sorbic acid. High pressure Hquid chromatography with ultraviolet detection is used to separate and quantify sorbic acid from other ultraviolet-absorbing species (57—59). Sorbic acid in food extracts is deterrnined by gas chromatography with flame ionization detection (60—62). 

Codex has also defined the various types of cocoa butter ia commercial trade (10). Press cocoa butter is defined as fat obtained by pressure from cocoa nib or chocolate Hquor. In the United States, this is often referred to as prime pure cocoa butter. ExpeUer cocoa butter is defined as the fat prepared by the expeUer process. In this process, cocoa butter is obtained direcdy from whole beans by pressing ia a cage press. ExpeUer butter usuaUy has a stronger flavor and darker color than prime cocoa butter and is filtered with carbon or otherwise treated prior to use. Solvent extracted cocoa butter is cocoa butter obtained from beans, nibs, Hquor, cake, or fines by solvent extraction (qv), usuaUy with hexane. Refined cocoa butter is any of the above cocoa butters that has been treated to remove impurities or undesirable odors and flavors. 

The Pott-Broche process (101) was best known as an early industrial use of solvent extraction of coal but was ended owing to war damage. The coal was extracted at about 400°C for 1—1.5 h under a hydrogen pressure of 10—15 MPa (100—150 atm) using a coal-derived solvent. Plant capacity was only 5 t/h with an 80% yield of extract. The product contained less than 0.05% mineral matter and had limited use, mainly in electrodes. 

Temperature The temperature of the extraction should be chosen for the best balance of solubility, solvent-vapor pressure, solute diffusivity, solvent selectivity, and sensitivity of product. In some cases, temperature sensitivity of materials of construction to corrosion or erosion attack may be significant. 

Transition metal oxides or their combinations with metal oxides from the lower row 5 a elements were found to be effective catalysts for the oxidation of propene to acrolein. Examples of commercially used catalysts are supported CuO (used in the Shell process) and Bi203/Mo03 (used in the Sohio process). In both processes, the reaction is carried out at temperature and pressure ranges of 300-360°C and 1-2 atmospheres. In the Sohio process, a mixture of propylene, air, and steam is introduced to the reactor. The hot effluent is quenched to cool the product mixture and to remove the gases. Acrylic acid, a by-product from the oxidation reaction, is separated in a stripping tower where the acrolein-acetaldehyde mixture enters as an overhead stream. Acrolein is then separated from acetaldehyde in a solvent extraction tower. Finally, acrolein is distilled and the solvent recycled. 

General trends are focused on reduced-solvent extractions or adsorption-based methods — enviromnentaUy friendly solvents for both solid and liquid samples. In recent decades, advanced techniques like supercritical fluid extraction (SFE), ° pressurized liquid extraction (PLE)," microwave-assisted extraction (MAE), ultrasound-assisted extraction, countercurrent continued extraction (www.niroinc.com), solid... 

In the past decade, new sample extraction techniques have been introduced to meet stricter criteria in the areas of food and agriculture, for example, enviromnentally friendly, non-toxic, fast, automated, robust, and cost-efficient techniques. Accelerated solvent extraction (ASE) and pressurized liquid extraction (PEE) are two methods developed for the extraction of chemicals of interest " and provide high yields and efficiency from a wide range of botanical, - animal, and biological samples. ASE and PLE combine solvents at elevated temperatures (40 to 200°C)... 

Accelerated solvent extraction (ASE) is a technique which attempts to merge the beneficial solvation properties of SFE with traditional organic solvents. Specifically, the sample is placed in an extraction vessel which can withstand high pressures while being maintained at a constant temperature. Extraction is carried out by pumping the extraction solvent through the samples for a limited time. As an example of the use of ASE, Richter and Covino extracted PCBs from a 10-g fish tissue sample with hexane... 

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