Ion exchangers extractants

Research should continue on traditional separation methods. For example, there is a continuing need for more selective extraction agents for liquid-liquid and ion-exchange extractions. High-temperature processes that use liquid metals or molten salts as extraction agents should have potential in nuclear fuel reprocessing and... 

Sulfate process streams are commonly used in metal recovery because they are readily derived by leaching with sulfuric acid or by oxidation of sulfidic ores. Metal recovery from such streams rarely involves the formation of metal sulfate complexes because the sulfate ion is a weak ligand for base metal cations and consequently acidic ion exchange extractants are commonly employed (see Section 9.17.5), which generate sulfuric acid which can be returned to the leaching stage,... 

Determination of Endothall in Drinking Water by Ion-Exchange Extraction, Acidic Methanol Methylation, and... 

Lan, Q., Bassi. A., Zhu, J.X. and Margaritis, A., Continuous protein recovery from whey using liquid-solid circulating fluidized bed ion-exchange extraction, Biotech. Bioeng., 78 (2002) 157-163. 

In this paper an overview of the developments in liquid membrane extraction of cephalosporin antibiotics has been presented. The principle of reactive extraction via the so-called liquid-liquid ion exchange extraction mechanism can be exploited to develop liquid membrane processes for extraction of cephalosporin antibiotics. The mathematical models that have been used to simulate experimental data have been discussed. Emulsion liquid membrane and supported liquid membrane could provide high extraction flux for cephalosporins, but stability problems need to be fully resolved for process application. Non-dispersive extraction in hollow fib er membrane is likely to offer an attractive alternative in this respect. The applicability of the liquid membrane process has been discussed from process engineering and design considerations. 

Schugerl 115] has recently furnished a detail analysis of the reactive extraction of penicdlin-G and V and precursors like phenyl and phenoxy acetic acids. Thirty different amines have been studied for reactive extraction of penicillins 116] in various solvents such as butyl acetate, chloroform, di-isopropyl ether, kerosene, dioctyl ether, etc. Tertiary amines in n-butyl acetate were found to be advantageous because of their low reactivity with solvent but the distribution coefficients of their complexes are significantly lower than those of secondary amines. While using quaternary ammonium salts for ion-exchange extraction, re-extraction is difficult and very large amounts of anion (e.g.. Cl ) are needed to recover penicillins. The basic relationship for distribution coefficient and extraction kinetics have now been fairly developed for amine-penicillin systems. 

Emulsion liquid membrane extraction of cephalosporins conform to the type II facilitated transport. Here the solute transport is either associated with a cotransport or counter-transport of an anionic species depending on whether ion-pair or ion-exchange extraction is exploited in the ELM system. 

Demonstration of facilitated sacrificial ion-exchange extraction processes to reduce the loss ofionk liquids and to increase extractive strength ofionk liquids... 

Physico-chemical treatment techniques, precipitation, sedimentation, air flotation, filtration, crystallization, chemical oxidation, wet air oxidation, super-critical water oxidation, chemical reduction, hydrolysis, nanofiltration, reserve osmosis, adsorption, ion exchange, extraction, distillation, rectification, evaporation, stripping, and incineration. 

N. J. K. Simpson, Ion exchange extraction, in N. J. K. Simpson, ed., Solid-Phase Extraction Principles, Techniques, and Applications, Marcel Dekker, New York, 2000, pp. 493-497. 

Sample preparation also includes certain matrix separation steps (e.g., by ion exchange, extraction chromatography and others), analyte enrichment (by co-precipitation and also ion exchange, e.g., Pu separation is performed using TEVA resin ) and preconcentration steps (e.g., by evaporation of solvent) off line or on line by high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) in order to improve the detection limits and avoid disturbing interference problems in ICP-MS. 

Np JRR-1 spent fuel Dowex 1 X-8 - HNO ion-exchange (Extraction of Np and Pu) TBP - HC1 solvent extraction 237 ( Np purification) a-ray spectrometry 1960 3... 

Elementary Practical Radiochemistry (Ladd and Lee 1964) contains 20 brief experiments that illustrate detection techniques such as measurement of ingrowth and decay, as well as ion exchange, extraction, and coprecipitation. The text Radioisotope Laboratory Techniques (Faires and Boswell 1981) primarily addresses nuclear physics, radionuclide production, and counting techniques. It briefly mentions laboratory apparatus but omits discussion of separation techniques. 

Transition-metal-containing polymers prepared by process I (Structure 10.1,1) are, as a rule, characterized by a low content of combined metal and are nsed primarily in ion-exchange extraction, preconcentration, and separation of metals by selective extraction [13-15],... 

Shahdeo, K. March, C. Kames, H.T. Postcolumn immunodetection following conditioning of the HPLC mobile phase by on-Hne ion-exchange extraction. Anal. Chem. 1997,69,4278. 

This part, on applications, covers the following unit operations 8. Evaporation 9. Drying of Process Materials 10. Stage and Continuous Gas-Liquid Separation Processes (humidification, absorption) 11. Vapor-Liquid Separation Processes (distillation) 12. Liquid—Liquid and Fluid-Solid Separation Processes (adsorption, ion exchange, extraction, leaching, crystallization) 13. Membrane Separation Processes (dialysis, gas separation, reverse osmosis, ultrafiltration) 14. Mechanical-Physical Separation Processes (filtration, settling, centrifugal separation, mechanical size reduction). 

Method and Application The precision requirement for 5Ca measurements (0.1 %o or better) is close to the limit of what is currently possible. For the analysis of bone, which contains about 40% Ca, the main interference, for ICP-MS (and PIMMS), is from Sr, and normal sample preparation therefore necessitates two ion-exchange extraction steps after dissolution of a few milligrams of bone in hydrochloric acid—one to extract Ca and the second to remove Sr. Mass-linear fractionation can be recognized by comparing 43/42 and 44/42 data from standards and references (Figure 35.5). 

A comprehensive overview of preconcentration techniques for uranium (VI) and thorium (IV) prior to analysis was published (Prasada Rao et al. 2006). The multitude of off-line techniques that were reviewed includes liquid-liquid extraction, liquid membranes, ion exchange, extraction chromatography, flotation, absorptive electrochemical accumulation, solid-phase extraction (SPE), and ion imprinting polymers. In addition, online preconcentration methods for uranium, thorium, and mixtures of the two are also briefly surveyed. This overview includes over 100 references and is a good source for finding a suitable preconcentration technique with regard to the enrichment factor, retention and sorption capacity, method validation, and types of real samples. The review article focused on samples in which the uranium was already in solution so that digestion procedures for solid samples were not discussed (Prasada Rao et al. 2006). 

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