Beschreibung: A series of impregnated sorbents based on di- tert -butyldicyclohexyl-18-crown-6 (DTBDCH18C6), various diluents (1-octanol, nitrobenzene, telomeric alcohol n3), and supports (Porolas-Т, LPS-500, hydrophobized silica gel) for removing tracer and weighable amounts of Sr ions from nitric acid solutions were prepared. The distribution coefficient of tracer amounts of 90 Sr on all the synthesized sorbents increases with an increase in the HNO 3 concentration in the range 1–7 M. The most pronounced increase in the sorption occurs with an increase in the HNO 3 concentration to 3 M. The maximal distribution coefficient of 90 Sr ( K d = 158 cm 3 g –1 ) is reached for the sorbent based on DTBDCH18C6 and 1-octanol in 7 M HNO 3 . Experiments on sorption of weighable amounts of Sr 2+ ions show that the static capacity of all the prepared sorbents for Sr in nitric acid solutions amounts to 4.3, 9.2, and 8.4 mg g –1 for the sorbents based on 1-octanol, nitrobenzene, and telomeric alcohol n3, respectively. The synthesized sorbents are suitable for radioanalytical determination of Sr radionuclides in liquid radioactive waste and in radioactively contaminated natural objects.

Beschreibung: Distribution of 210 Po in thalli of soil and wood (epiphytic) lichens was studied. Four fractions containing the corresponding 210 Ро forms were obtained by sequential extraction: (1) intercellular, (2) extracellular, (3) intracellular, and (4) insoluble thallus residue. The 210 Ро uptake by lichens is mainly passive, as the total content of the radionuclide in fractions 1, 2, and 4 reaches 88–97%. From 3 to 12% of 210 Ро is taken up actively (fraction 3), and for soil lichens this parameter is approximately 2.75 times higher than for epiphytic lichens. Presumably, 210 Ро is supplied into soil and epiphytic lichens in the form of different chemical compounds and is therefore characterized by different bioavailability.

Beschreibung: The effect of a series of halogenated diluents [bis(octafluoroamyloxy)methane, phenyl trifluoromethyl sulfone, methyl dodecafluoroheptyl ether, m -nitrobenzotrifluoride, hexachlorobutadiene, CHCl 3 , CCl 4 ] on the extraction of spent nuclear fuel solution components [HNO 3 , U(VI), An(IV), Zr, and Tc] into 30% TBP was studied and mathematically described using improved A.M. Rozen’s model. Comparison with the TBP–paraffins extraction system was made.

Beschreibung: A new mesoporous adsorbent for uranium removal from waste effluents was prepared, characterized, and impregnated with trioctylamine. The adsorption efficiency was investigated as a function of pH, contact time, initial uranium concentration, competing ions, solid/liquid ratio, and temperature using batch sorption techniques. The maximum adsorption capacity was 21.9 mg g –1 at pH 5. The equilibrium data fit well with the Langmuir adsorption isotherm. Kinetic study showed that the process was fast and reached equilibrium within 60 min. The kinetic data fit well with the pseudo-second-order law. Thermodynamic data show that the process is spontaneous and exothermic.

Beschreibung: The structure and properties of the needle-like phase of crystalline compounds of the general composition Co(NH 3 ) 6 NpO 5 · n H 2 O, precipitated from alkaline Np(VII) solutions with [Co(NH 3 ) 6 ] 3+ ions, were studied. The needle-like phase under the layer of the mother liquor is unstable and transforms into a platelike phase identified as [Co(NH 3 ) 6 ][NpO 4 (OH) 2 ]·2H 2 O ( 1 ). In the structure of 1 , all the Np atoms are equivalent, but the Mössbauer spectrum recorded at a liquid helium temperature revealed the presence of two nonequivalent Np atoms. The isolated needle-like phase, according to single crystal X-ray diffraction data, at 100 K has the composition [Co(NH 3 ) 6 ] 3 [NpO 4 (OH) 2 ] 3 ·4H 2 O ( 2 ). In the structure of 2 , there are two crystallographically independent Np(VII) atoms. The Np(1) atom is in the inversion center, and the Np(2) atom occupies a general position. The structure of 1 was additionally refined, and the structures of 1 and 2 were compared. Both compounds have a similar structure, but the structure of 2 is less ordered, and the formation of both structures is influenced by hydrogen bonds involving water molecules and [NpO 4 (OH) 2 ] 3– ions. In the structure of 1 , hydrogen bonds of type O–H···O form a three-dimensional network. In the structure of 2 , the O–H···O hydrogen bonds are weaker and form a two-dimensional network. In the structure of 1 , there are two water molecules per [NpO 4 (OH) 2 ] 3– anion, and in the structure of 2 , 4/3 water molecules. Needle-like phase 2 in contact with solutions transforms into stable platelike phase 1 with dense packing and a three-dimensional system of hydrogen bonds. The size of needle-like crystals increases, and the rate of their transformation into platelike crystals decreases with increasing alkali concentration and decreasing temperature. The influence of the experiment conditions on the interaction of Np(VII) with [Co(NH 3 ) 6 ] 3+ ions in weakly alkaline (0.05–0.15 M) solutions was also studied. The precipitates formed are characterized by the ratio [NpO 4 (OH) 2 ] 3– : [Co(NH 3 ) 6 ] 3+ = 2: 1 and are identified as the known compound LiCo(NH 3 ) 6 Np 2 O 8 (OH) 2 ·2H 2 O.

Beschreibung: An asymmetric model of virial expansion of the Gibbs free energy of solution, VD-AS, was suggested. Partial and molar thermodynamic functions of UO 2 (ClO 4 ) 2 –H 2 O, UO 2 Cl 2 –H 2 O, and UO 2 (NO 3 ) 2 –H 2 O binary solutions at 25°C were calculated using this model. The calculations show that the solutions are characterized by different, sometimes extremely large, deviations from ideality. The suggested model is considerably more accurate and stable than the most widely used Pitzer’s model of electrolyte solutions.

Beschreibung: Published data on the reaction of H 2 O 2 with nitrogen oxides and HNO 2 were analyzed and summarized as applied to the problems of trapping nitrogen oxides from off-gases. H 2 O 2 reacts only with NO and HNO 2 dissolved in aqueous solution, and the NO solubility increases with increasing HNO 3 concentration. Examples of enhancing the efficiency of trapping nitrogen oxides by using Н 2 О 2 are presented.

Beschreibung: Uranyl malonate monohydrate [UO 2 (mal)(H 2 O)], where mal 2– is malonate ion, was synthesized and studied by single crystal X-ray diffraction. The main structural units are electrically neutral [UO 2 (mal)(H 2 O)] layers belonging to crystal-chemical group AQ 21 М 1 (A = UO 2 2+ , Q 21 = mal 2– , M 1 = H 2 O) of uranyl complexes. Specific features of the packing of the uranium-containing complexes are discussed on the basis of Voronoi–Dirichlet tessellation. The structural differences between the monohydrate synthesized and the known uranyl malonate trihydrate are considered.

Beschreibung: A method was developed for immobilization of prepared human chorionic gonadotropin (β-hCG) antisera on fresh plastic beads through a covalent immune bridge. Such covalent immune-coated antisera on plastic beads were used in the development of a noncentrifugation radioimmunoassay. 125 I-β-hCG was prepared using different oxidizing agents. The solid-phase RIA system developed was found to well compete with the conventional method.

Beschreibung: Previously unknown arsenates of hexavalent U, Np, and Pu, (H 3 O)[(UO 2 )(AsO 4 )]·3H 2 O ( I ), (H 3 O)· [(NpO 2 )(AsO 4 )]·3H 2 O ( II ), and (H 3 O)[(PuO 2 )(AsO 4 )]·3H 2 O ( III ), were synthesized under hydrothermal conditions. The crystal structure of the compounds was determined, and their absorption spectra were measured. The compounds crystallize in tetragonal space group P 4/ nmm .