Extractions, Application

Spray Towers These are simple gravity extractors, consisting of empty towers with provisions for introducing and removing liquids at the ends (see Fig. 15-32). The interface can be run above the top distributor, below the bottom distributor, or in the middle, depending on where the best performance is achieved. Because of severe axial back mixing, it is difficult to achieve the equivalent of more than one or two theoretical stages or transfer units on one side of the interface. For this reason they have only rarely been applied in extraction applications. 

Extraction (discussed in Chapter 5) uses the selective adsorption of a component in a liquid to separate specific molecules from a stream. In application extraction may be coupled with its cousins, extractive distillation and azeotropic distillation, to improve extraction efficiency. Typical refinery extraction applications involve aromatics recovery (UDEX) and lubricants processing (furfural, NMP). Extractive distillation and azeotropic distillation are rarely employed in a refinery. The only... 

The actual stage can be a mixing vessel, as in a mixer-settler used for solvent extraction applications, or a plate of a distillation or gas absorption column. In order to allow for non-ideal conditions in which the compositions of the two exit streams do not achieve full equilibrium, an actual number of stages can be related to the number of theoretical stages, via the use of a stage-efficiency factor. 

A wide variety of extraction column forms are used in solvent extraction applications and many of these, such as rotary-disc contactors (RDC), Oldshue-Rushton columns, and sieve-plate column extractors, have rather distinct compartments and a geometry, which lends itself to an analysis of column performance in terms of a stagewise model. As the compositions of the phases do not come to equilibrium at any stage, however, the behaviour of the column is therefore basically differential in nature. 

P.D. McDonald and E.S.P. Bouvier, Solid Phase Extraction Applications Guide and Bibliography, A Resource for Sample Preparation Methods Development, Waters, Milford, MA... 

In the deformulation of PE/additive systems by mass spectrometry, much less fragmentation was observed with DCI-MS/MS using ammonia as a reagent gas, than with FAB-MS [69]. FAB did not detect all the additives in the extracts. The softness and the lack of matrix effect make ammonia DCI a better ionisation technique than FAB for the analysis of additives directly from the extracts. Applications of hyphenated FAB-MS techniques are described elsewhere low-flow LC-MS (Section 7.3.3.2) and CE-MS (Section 7.3.6.1) for polar nonvolatile organics, and TLC-MS (Section 7.3.5.4). 

Efficiency of Extraction. Selectivity of Extraction. Extraction Systems. Extraction of Uncharged Metal Chelates. Methods of Extraction. Applications of Solvent Extraction. 

Taylor R.L., Grebe S.K., and Singh R., High throughput analysis of 25-hydroxyvitamins D2 and D3 by LC-MS/ MS using automated online extraction. Application poster, Mayo Clinic and Cohesive Technologies. 

Remaud GS, Martin YK, Giles G, Martin GJ (1997) Detection of natural vanilla flavors and extracts Application of the SNIF-NMR to vanillin and p-hydroxybenzaldehyde. J Agric Food Chem 45 859-866... 

Solid phase extraction applicable to extracts of carrot, orange juice, peach, tomato, vegetable soup. Load hexane extracts onto alumina N Sep-Pak cartridge. Elute a- and /3-carotene with hexane/acetone, 96.5 3.5 and /3-cryp-toxanthin with acetone... 

Erlinger, C.V. 1998. Towards a physical interpretation of third phase formation in liquid-liquid extraction. Application to the DIAMEX process for the treatment of high radioactive nuclear wastes. Thesis. University Paris XI, Paris. 

Still, in most liquid—liquid distribution systems one of the liquid phases is more aqueous while the other is mainly non-aqueous. Therefore, a major consideration of the choice of the solvent for solvent extraction is its immiscibility with water and the expected losses of the solvent to the aqueous phase. In many solvent extraction applications the solvent is used as a diluent for an active extractant, which may be either a solid or a liquid when neat. In these cases, where a separate active extractant is used, the chemical processes taking place in the selective extraction of the desired solute or solutes and their recovery in the stripping stage are of prime importance, but a discussion of which is outside the... 

The ability of the centrifugal extractor to solve difficult liquid-liquid separation problems, as illustrated in the previous examples, has allowed its use in a wide range of extraction applications. The long history of use has given it a general acceptance in chemical manufacturing—an acceptance not shared by the broader application of gas-liquid interactions. 

In the absence of a solvent-recovery method, entrainment is expected to be the major solvent-loss factor in all solvent-extraction applications [94], including CSSX [89], potentially amounting to several hundred ppm of the aqueous effluent. Solvent loss is known to be the economic determinant in most commercial solvent-extraction systems... 

The table below lists the value of dielectric constants of methanol-water mixtures as a function of their respective mass/mass% composition at various temperatures.1 This information is useful for a variety of chromatographic and extractive applications. 

Remaud, C.S., Martin, Y.-L., Martin, C.C. and Martin, C.J. (1997) Detection of sophisticated adulterations of natural vanilla flavors and extracts application of the SNIF-NMR method to vanillin and p-hydroxyben-zaldehyde. Journal of Agricultural and Food Chemistry 45, 859-866. 

In recent years, supercritical fluid extraction has received widespread attention for the removal of non- or low-volatile organic components from liquid and solid matrices. This process has many potential applications like analytical extractions, applications in the food and drug industry, activated carbon regeneration or soil remediation. 

Efficiency of extraction. Selectivity of extraction. Extraction systems. Extraction of uncharged metal chelates. Methods of extraction. Applications of solvent extraction. 

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