Solution-solvent extraction

Other Organic Processes. Solvent extraction has found appHcation in the coal-tar industry for many years, as for example in the recovery of phenols from coal-tar distillates by washing with caustic soda solution. Solvent extraction of fatty and resimic acid from tall oil has been reported (250). Dissociation extraction is used to separate y -cresol fromT -cresol (251) and 2,4-x5lenol from 2,5-x5lenol (252). Solvent extraction can play a role in the direct manufacture of chemicals from coal (253) (see Eeedstocks, coal chemicals). 

The future will bring further increase in concern over the environmental impact of chemical operations. The liquid effluents must not only be controlled, they must also be rendered harmless to the environment. This requires removal of the hazardous substances. For many of the dilute waste solutions, solvent extraction has proved to be an effective process. This is even more true for recycling of mixed metals from various industries. Nevertheless, the increasing amounts of wastes from human activities require much more to be done in this field. 

Benzoylphenylhydroxylamine (17 R1 = R2 = Ph) forms complexes with V, Sn, Ti and Zr in 5 to 9 M HC1 but only that of vanadium is extractable into chloroform, permitting a selective determination of that element in chrome ores. A-Cinnamoyl-V-phenylhydroxylamine is even more sensitive. In less acid solutions solvent extractable complexes are formed with a number of other cations and, for example, an orange-red complex of uranium(VI) is extracted by V-benzoyl-iV-phenylhydroxylamine into chloroform.52... 

In the case of the Canadian yttrium-heavy rare earth concentrate, this is leached with HN03, causing all rare earths to go into solution. Solvent extraction separates yttrium from the other heavy rare earths, each of which can eventually be separated by further solvent extraction. In the case of xenotime, this is leached with hot H2S04 and separation of yttrium and the heavy rare earths completed in ion-exchange columns. The liquid-liquid organic solvent extraction cycle is complete within 5-10 days and is a continuous process. The resin ion-exchange cycle requires 60—90 days and is a batch process. Both processes result in pure rare earth oxides and chemicals. 

Tachimori, S., Suzuki, S., Sasaki, Y., Apichaibukol, A. 2003. Solvent extraction of alkaline earth metal ions by diglycolic amides from nitric acid solutions. Solvent Extraction and Ion Exchange 21(5) 707-715. 

Solvent extraction processes have been devised for treating etchants, removing impurities from bleed streams in primary metallurgical processes, and treating similar solutions. Solvent extraction has also been tested for treating mine walers. Unfortunately, the liquid extractants and diluents invariably have finite solubilities in water, which may be high enough to deteriorate water quality. 

Raut, D.R., Evaluation of two calix-crown-6 ligands for the recovery of radio cesium from nuclear waste solutions Solvent extraction and liquid membrane studies, J. Membr. Sci. 429, 197, 2013. 

Product Solids Solute Solvent Extraction Time (min)... 

Riddle,C.L., J.D. Baker, J.D. Law, C.A. McGrath, D.H. Meikrantz, B.J. Mincher, D.R. Peterman, and T.A. Todd. 2005. Fission product extraction (FPEX) Development of a novel solvent for the simultaneous separation of strontium and cesium from acidic solutions. Solvent Extraction and Ion Exchange 23 449-461. 

Solvent extraction is frequently used in the organic laboratory to separate or isolate a desired compound from a mixture or from impurities. Solvent extraction methods are readily adapted to microscale work because small quantities are easily manipulated in solution. Solvent extraction methods are based on the solubOity characteristics of organic substances in the solvents used in a particular separation procedure. Liquid-liquid and solid-liquid extractions are the two major types of extractions used in the organic laboratory. 

Chemical reactions occur in many commonly practiced separation processes. By chemical reactions, we mean those molecular interactions in which a new species results (Prausnitz et al, 1986). In a few processes, there will he hardly any separation without a chemical reaction (e.g. isotope exchange processes). In some other processes, chemical reactions enhance the extent of separation considerably (e.g. scrubbing of acid gases with alkaline absorbent solutions, solvent extraction with complexing agents). In still others, chemical reactions happen whether intended or unintended estimation of the extent of separation requires consideration of the reaction. For example, in solvent extraction of organic acids, the extent of acid dissociation in the aqueous phase at a given pH should be taken into account (Treybal, 1963, pp. 38-41). Chemical equilibrium has a secondary role here, yet sometimes it is crucial to separation. 

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