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Problems of the development of potentiometric sensors and multisensor systems for the determination of rare-earth elements in aqueous solutions are considered. The efficiency of the approach to the fabrication of sensors based on the application of substances and regularities used in solvent extraction is shown. Possibilities of multisensor systems for the selective determination of individual lanthanides in complex mixtures are demonstrated. [ABSTRACT FROM AUTHOR]

The concentration of molybdenum(VI) in dissolved spent nuclear fuel is comparable with the concentrations of Tc, and the minor actinides (Np, Am). Therefore it is of great interest to understand its behavior under conditions imposed by separation processes. The simultaneous extraction ability of ortho, meta, and para isomers of N,N′-diethyl- N,N′-ditolyl-dipicolinamide (EtTDPA) for molybdenum and technetium were investigated in a large range of nitric and hydrochloric acid conditions. Molybdenum shows no increase in extraction at higher concentrations of nitric acid giving a solvate number n=0 with all isomers of EtTDPA, while Mo shows great extractability from HCl. Technetium distribution ratios decrease with increasing concentrations of nitrate showing indication of ion exchange occurring between TcO4 − anions. Et(m)TDPA and Et(p)TDPA show the greatest extractability, with 60% of the total technetium extracted into the organic phase at 1M HNO3 − anions. Et(m)TDPA and Et(p)TDPA show the greatest extractability, with 60% of the total technetium extracted into the organic phase at 1M HNO3. [ABSTRACT FROM AUTHOR]

A procedure was developed for conversion of spent UNEX solvent into a solid infusible resin, insoluble in aqueous alkali and acid solutions and organic solvents, by condensation with phenol and paraform. Incorporation of phenyl trifluoromethyl sulfone into the resin was confirmed by physicochemical methods. Resistance of the cured resin to high temperatures was proved by thermogravimetry. The developed procedure can also be applied to other organic wastes containing weakly reactive aromatic compounds such as nitrobenzotrifluoride, 1,2-dichlorobenzene, and nitrobenzene. [ABSTRACT FROM AUTHOR]

Extraction of nitric acid, perchloric acid, americium, and europium with dialkyldiarylamides of 2,6-pyridinecarboxylic (dipicolinic) acid in polar fluorinated solvents (diluents) was analysed. Among the extractants studied N, N′-diethyl-N, N′-ditolylamide dipicolinate is characterized by the best extraction properties. On passing from nitric to perchloric acid solutions extraction of metals sharply increases. Extraction of americium from nitric acid solutions is significantly greater as compared with europium (separation coefficient reaches 6), whereas extraction of americium and europium from perchloric acid solutions is nearly similar. The effect of diluent on the extraction was analyzed; for different diluents the maximum of extraction from perchloric acid solutions shifts form 3 to 6 M. [ABSTRACT FROM AUTHOR]

Extraction of Am and Eu with N,N′-substituted pyridine-2,6-dicarboxamides in fluorinated diluents was studied. N,N′-Diethyl- N,N′-di( p-tolyl)pyridine-2,6-dicarboxamide (EtTPDA) is readily soluble in fluorinated diluents, and its solutions allow the extraction of TPE and REE from nitric acid solutions. The extraction ability of EtTPDA in fluorinated polar diluents is higher than in CHCl3. In the extraction with EtTPDA, the Am/Eu selectivity is independent of the extractant concentration and decreases with an increase in the acidity of the medium. Americium is extracted with EtTPDA better than Eu, which allows selective recovery of Am at moderate HNO3 concentrations. [ABSTRACT FROM AUTHOR]

The sorption ability of a solid-phase extractant with dipicolinic acid N,N′-diethyl-N,N′-di(p-tolyl) diamide groups on fibrous polyacrylonitrile (PAN) matrix was studied. The conditions for immobilization of the reagent on PAN disks were determined, and the possibility of sorption preconcentration and separation of U(VI), Pu(IV), Am(III), and Eu(III) from 2-6 M HNO3 solutions was examined. The solid-phase extractant obtained exhibits good kinetic properties and can be used for separation of Am(III) И Eu(III). [ABSTRACT FROM AUTHOR]

Extraction of Cs, Sr, Eu, U, Np, and Am with mixtures of dipicolinic acid diamides with chlorinated cobalt dicarbollide was studied. A synergistic effect was revealed. [ABSTRACT FROM AUTHOR]