Sohd-hquid extractions

Supercritical Extraction. The use of a supercritical fluid such as carbon dioxide as extractant is growing in industrial importance, particularly in the food-related industries. The advantages of supercritical fluids (qv) as extractants include favorable solubiHty and transport properties, and the abiHty to complete an extraction rapidly at moderate temperature. Whereas most of the supercritical extraction processes are soHd—Hquid extractions, some Hquid—Hquid extractions are of commercial interest also. For example, the removal of ethanol from dilute aqueous solutions using Hquid carbon dioxide... 

Fincan, M., DeVito, F., and Dejmek, P., Pulsed electric field treatment for sohd-hquid extraction of red beetroot pigment, J. Food Eng., 64, 381, 2004. 

Centrifugation to aid an operation has found considerable use in the General Medical Science/Atomic Energy Commission approach to automation pioneered hy Anderson [S], and was also used hy Bartels et al. [6], in the design of a sohd-hquid extraction system. 

Production Technology. Processes for extraction of P2O3 from phosphate rock by sulfuric acid vary widely, but all produce a phosphoric acid—calcium sulfate slurry that requires soHds-Hquid separation (usually by filtration (qv)), countercurrent washing of the soHds to improve P2O3 recovery, and concentration of the acid. Volatilized fluorine compounds are scmbbed and calcium sulfate is disposed of in a variety of ways. 

In order to make a multipurpose plant even more versatile than module IV, equipment for unit operations such as soHd materials handling, high temperature/high pressure reaction, fractional distillation (qv), Hquid—Hquid extraction (see Extraction, liquid-liquid), soHd—Hquid separation, thin-film evaporation (qv), dryiag (qv), size reduction (qv) of soHds, and adsorption (qv) and absorption (qv), maybe iastalled. 

Uranium Purification. Subsequent uranium cycles provide additional separation from residual plutonium and fission products, particularly zirconium— niobium and mthenium (30). This is accompHshed by repeating the extraction/stripping cycle. Decontamination factors greater than 10 at losses of less than 0.1 wt % are routinely attainable. However, mthenium can exist in several valence states simultaneously and can form several nitrosyl—nitrate complexes, some for which are extracted readily by TBP. Under certain conditions, the nitrates of zirconium and niobium form soluble compounds or hydrous coUoids that compHcate the Hquid—Hquid extraction. SiUca-gel adsorption or one of the similar Hquid—soHd techniques may also be used to further purify the product streams. 

After epoxidation a distillation is performed to remove the propylene, propylene oxide, and a portion of the TBHP and TBA overhead. The bottoms of the distillation contains TBA, TBHP, some impurities such as formic and acetic acid, and the catalyst residue. Concentration of this catalyst residue for recycle or disposal is accompHshed by evaporation of the majority of the TBA and other organics (141,143,144), addition of various compounds to yield a metal precipitate that is filtered from the organics (145—148), or Hquid extraction with water (149). Low (<500 ppm) levels of soluble catalyst can be removed by adsorption on soHd magnesium siUcate (150). The recovered catalyst can be treated for recycle to the epoxidation reaction (151). 

Sedimentation is also used for other purposes. For example, relative motion of particles and Hquid iacreases the mass-transfer coefficient. This motion is particularly useful ia solvent extraction ia immiscible Hquid—Hquid systems (see Extraction, liquid-liquid). An important commercial use of sedimentation is ia continuous countercurrent washing, where a series of continuous thickeners is used ia a countercurrent mode ia conjunction with reslurrying to remove mother liquor or to wash soluble substances from the soHds. Most appHcations of sedimentation are, however, ia straight sohd—Hquid separation. 

The hquid vehicle in a slurry should have a low vapor pressure for Hquid extraction and drying be compatible with the soHds and casting mold be inexpensive and be capable of dissolving and dispersing deflocculants and other additives. Distilled or deionized water is generally used as the Hquid vehicle, however, organic Hquids must be used for such moisture sensitive oxide powders as CaO and MgO, and for oxidation sensitive nonoxide powders, eg, AIN. 

By-Products. The biomass from the fungal fermentation process is called mycellium and can be used as a supplement for animal feed since it contains digestable nutrients (25,26). The lime-sulfuric purification and recovery process results in large quantities of calcium sulfate cake, which is usually disposed of into a landfill but can find limited use in making plaster, cement, waUboard, or as an agricultural soil conditioner. The Hquid extraction purification and recovery process has the advantage of Htde soHd by-products. 

Carrot oil—The Hquid or the soHd portion of the mixture, or the mixture itself obtained by the hexane extraction of edible carrots (Daucus carota L.) with subsequent removal of the hexane by vacuum distillation. The resultant mixture of soHd and Hquid extractives consists chiefly of oils, fats, waxes, and carotenoids naturally occurring in carrots. 

Various methods ofachieving preconcentration have been applied, including Hquid -hquid extraction, precipitation, immobihzation and electrodeposition. Most of these have been adapted to a flow-injection format for which retention on an immobihzed reagent appears attractive. Sohd, sihca-based preconcentration media are easily handled [30-37], whereas resin-based materials tend to swell and may break up. Resins can be modified [38] by adsorption of a chelating agent to prevent this. Sohds are easily incorporated into flow-injection manifolds as small columns [33, 34, 36, 39, 40] 8-quinolinol immobilized on porous glass has often been used [33, 34, 36]. The flow-injection technique provides reproducible and easy sample handhng, and the manifolds are easily interfaced with flame atomic absorption spectrometers. 

Kiimmerer K., A. Eitel, U. Braun, P. Hubner, E. Daschner, G. Mascart, M. Milandri, E. Reinthaler, and J. Verhoef (1997a). Analysis of benzalkonium chloride in the effluent from European hospitals by sohd-phase extraction and high-performance hquid chromatography with post-colunm ion-pairing and fluorescence detection. Journal of Chromatography A 774 281-286. 

D. Barron, J. Barbosa, J. A. Pascual and J. Segura, Direct determination of anabolic steroids in human urine by onhne sohd-phase extraction/hquid chromatography/mass spectrometry , J. Mass Spectrom. 31 309-319 (1996). 

J. Huwyler, S. Rufer, E. Kusters and J. Drewe, Rapid and highly automated determination of morphine and morphine glucuronides in plasma by on-hne sohd-phase extraction and column hquid chromatography , J. Chromatogr. B 674 57-63 (1995). 

S. Bompadre, L. Ferrante, F. P. Alo and L. Leone, On-line sohd-phase extraction of ceftazidime in serum and determination by high-performance hquid chromatography , J. Chromatogr. B 669 265 -269 (1995). 

H. Zehender, J. Denouel, M. Roy, L. Le Saux and P. Schaub, Simultaneous determination of terbinahne (Lamisil) and five metabolites in human plasma and urine by high-performance hquid chromatography using on-hne sohd-phase extraction , J. Chromatogr. B 664 347-355 (1995). 

O. V. Olesen and B. Poulsen, On-hne fuhy automated determination of clozapine and desmethylclozapine in human serum by sohd-phase extraction on exchangeable cartridges and hquid chromatography using a methanol buffer mobile phase on unmodified silica , J. Chromatogr. 622 39-46 (1993). 

V. Ascalone, P. Guinebault and A. Rouchouse, Determination of mizolastine, a new antihistaminic drug, in human plasma by liquid-liquid extraction, sohd-phase extraction and column-switching tecniques in combination with high-performance hquid chromatography , J. Chromatogr. 619 275-284(1993). 

G. Garcfa-Encina, R. Farran, S. Puig and L. Martinez, Validation of an automated hquid chromatographic method for omeprazole in human plasma using on-hne sohd-phase extraction , J. Pharm. Biomed. Anal. 21 371-382 (1999). 

M. Jemal, D. Teitz, Z. Ouyang and S. Khan, Comparison of plasma sample purification by manual liquid-liquid extraction, automated 96-well liquid-liquid extraction and automated 96-well sohd-phase extraction for analysis by high-performance hquid chromatography with tandem mass spectrometry , J. Chromatogr. B 732 501-508 (1999). 

Lerch, R. and W. Donald (1994). Analysis of hydroxylated atrazine degradation products in water using sohd-phase extraction and high-performance hquid chromatography. J. Agric. Food Chem., 42 922-927. 

Zhou, Q., Y. Ding, and J. Xiao. 2006. Sensitive determination of thiamethoxam, imidacloprid and acet-amiprid in environmental water samples with sohd-phase extraction packed with multiwalled carbon nanotubes prior to high-performance hquid chromatography. Anal. Bioanal. Chem. 386 1520-1525. 

Lopez-Jimenez, F.J., S. Rubio, and D. Perez-Bendito. 2005. Determination of phthalate esters in sewage by hemimicelles-based sohd-phase extraction and hquid chromatography-mass spectrometry. Anal. Chim. Acta 551 142-149. 

Fuh, M.R., Wu, T.Y., and Lin, T.Y. Determination of amphetamine and methamphet-amine in urine by sohd phase extraction and ion-pair hquid chromatography-electro-spray-tandem mass spectrometry. Talanta 2006, 68,987-991. 

Soils, sediments, and biosolids are complex matrices and extraction of organic contaminants and their TPs has been more challenging than in aqueous media since co-extracted material present in these samples can severely reduce the efficiency of extraction. Therefore, it is essential to develop effective methods for extraction and purification. Due to the thermolabile properties and polar nature of many TPs, traditional extraction methods such as Soxhlet are not appropriate and other techniques such as pressurized Hquid extraction (PLE), microwave-assisted extraction (MAE), microwave-assisted Soxhlet extraction (MASE), and ultrasonic solvent extraction are more suitable. A summary of extraction methods applicable to the determination of pesticide TPs in soHd matrices (soil) is presented in Table 4. 

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