Macrocyclic extractables

Dozol, J.F., Bohmer, V., McKervey, A. et al. 1997. New macrocyclic extractants for radioactive waste treatment Ionizable crown ethers and functionalized calixarenes. Report EUR-17615. 

J.-F. Dozol, V. Bohmer, M. A. McKervey, F. Lopez-Calahorra, D. N. Reinhoudt, M. J. Schwing, R. Ungaro and G. Wipff, New macrocyclic extractants for radioactive waste treatment Ionizable crown ethers and functionalized calixarenes, EUR-OP Reference CG-NA-17615-EN-C (EUR-17615), European Commission, Nuclear Science and Technology, Luxembourg, 1997. 

The most stable are the macrocyclic extractants, with radiolytic degradation yields lower than 1 molecule/100 eV (7), and especially the calix-arenes G(-calixarene) <0.1 (72) ... 

Figure 4. The pre-assembly of bis-salicylaldoxime 14-membered pseudo-macrocyclic extractant in non-polar solvents.

Gas Chromatography of Macrocyclic Extractables. Analyses of the various macrocyclic extractable fractions by GLC were performed using an F M Model 810 Research Chromatograph, equipped with a flame ionization detector, a 20-ft. silicone Hi-Pak column and using helium gas as carrier. The analyses were conducted at a carrier gas rate of 50 cc./min., injection port temperature of 280°C., and programmed at 20°C./min. in the 60-300°C. range and holding isothermally at 300°C. for an additional 8 minutes. 

Low Voltage Mass Spectrometry of Macrocyclic Extractables. Nominal parent mass analyses of the macrocyclic extractables, obtained from typical polymerization products of cyclooctene and 1,5-cyclooctadiene, were performed on a Model MS-9 double focusing mass spectrometer (Associated Electrical Industries, England) at a resolution of 1/1000 and an emission of 7.0 e.v. Samples were introduced directly into the source chamber by the direct-probe technique. The temperature range during the experiment was 125°-200°C., and the source pressure was maintained in the 0.1-3 X 10-6 torr range. In addition, a high resolution measurement was carried out on the mass number 220 to identify the two components present at that mass number. 

Composition of Macrocyclic Extractables. The quantitative procedure used in this work to separate and determine the level of the low molecular weight oily fraction is based on using a solvent mixture (hex-... 

Usually the description of the phase transfer behavior is presented in a simplified form based on the overall extraction equilibrium. This is illustrated schematically for a simple ion-pair extraction of a metal ion by a neutral macrocyclic extractant in Fig. 4.4. 

CEA Cadarache and seven European universities were involved in a research programme to synthesize and test new macrocyclic extractants (crown-ethers and calixarenes). The main aim of this study was to selectively remove caesium, strontium and actinides from medium level liquid waste (MLLW) to decontaminate them to the extent that they can be disposed of in a near surface site. A new calixarene has been synthesized by the University of Parma, which has a cesium/sodium selectivity 100 times higher than that of the best current extractant for cesium. The large selectivity of this molecule has been explained theoretically. The results obtained for cesium extraction from simulated MLLW have been confirmed with real HLLW. Finally, new functionalized calixarenes have been also synthesized, which are more selective to actinides and lanthanides than the best extractant available on the market. 

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