V. A. Babain

Reprocessing of Spent Solvent of the UNEX Process

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.

Extraction of americium and europium from perchloric acid solutions with N,N′-dialkyl-and N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides

Extraction of americium and europium from perchloric acid solutions with pyridine-2,6-dicarboxamides was studied. The solvate numbers and Am/Eu separation factors were determined.

Extraction of microamounts of Eu and Am into nitrobenzene using a synergistic mixture of chlorinated hydrogen dicarbollylcobaltate and N,N′-diethyl-N,N′-diphenyl-2,6-dipicolinamide

Extraction of microamounts of Eu and Am with a nitrobenzene solution of chlorinated hydrogen dicarbollylcobaltate (H+B−) in the presence of N,N′-diethyl-N,N′-diphenyl-2,6-dipicolinamide (EtPhDPA, L) was studied. The equilibrium data were interpreted assuming that the complexes HL+, HL2+, ML23+, ML33+, and ML4/3+ (M3+ = Eu3+, Am3+) are extracted into the organic phase. The extraction and stability constants of the species in water-saturated nitrobenzene were determined. The stability constants of the related complexes EuLn3+ and AmLn3+, where n = 2, 3, 4, in this medium are comparable.

Various flowsheets of actinides recovery with diamides of heterocyclic dicarboxylic acids

Solvents on the base of diamides of heterocyclic dicarboxylic acids are promising alternatives for studied Grouped ActiNide EXtraction (GANEX) solvents. Advantage of these ligands is the possibility of simultaneous extraction not only of residual uranium and plutonium, but also minor actinides—neptunium, americium and curium. Two flowsheets on the base of diamides of heterocyclic dicarboxylic acids for separation of actinides form acidic solutions were developed, tested in laboratory scale and compared. Both flowsheets allow separation of more than 99.95% of actinides from raffinates with high content of lanthanides.

New polar fluorinated diluents for diamide extractants

The extraction properties of TODGA solutions in novel polar fluorinated diluents were investigated. The extraction of nitric acid, Am and lanthanides was studied. It was found that aromatic fluorinated diluents provide the highest loading capacity of organic phase comparing with aliphatic diluents. A new solvent on the base of TODGA in meta-nitrobenzotrifluoride is the most promising for technological purposes.

A novel dipicolinamide-dicarbollide synergistic solvent system for actinide extraction

Abstract Solvent extraction studies of several actinide ions such as Am(III), U(VI), Np(IV), Np(VI), Pu(IV) were carried out from nitric acid medium using a synergistic mixture of N, N′-diethyl-N, N′-di(para)fluorophenyl-2,6-dipicolinamide, (DEtD(p)FPhDPA, DPA), and hydrogen dicarbollylcobaltate (H+CCD−) dissolved in phenyltrifluoromethylsulphone (PTMS). The effects of different parameters such as aqueous phase acidity (0.01 – 3 M HNO3), oxidation states of metal ions, ligand concentration, nature of diluent and temperature on the extraction behavior of metal ions were studied. The extracted Am(III) species was determined as H+[Am(DPA)2(CCD)4]−. With increasing aqueous phase acidities, the extractability of both Am(III) and Eu(III) was found to decrease. The synergistic mixture showed better extraction in mM concentrations as compared to previously studied dipicolinamides. The thermodynamic studies were performed to calculate heat of extraction reaction and the extraction constants. The proposed synergistic mixture showed good extraction for all the metal ions, though lanthanide actinide separation results are not encouraging.

Determination of 99Tc in aqueous solutions of various cationic compositions using a varian 725-ES inductively coupled plasma optical emission spectrometer

A procedure was developed for determining the gravimetric concentration of 99Tc in aqueous solutions from spent nuclear fuel reprocessing without their preliminary separation, using an inductively coupled plasma optical emission spectrometer (ICP-OES). The optimal conditions for minimizing spectral and matrix interferences were determined. They allowed the lower limit of Tc determination in process salt solutions to be decreased from 1 to 0.25 mg l−1.