Vol 60, No 2 (2018)

Mixed-cation salts of the general composition NaM₂[NpO₄(OH)₂]·4H₂O, where M = Rb (I, II) and Cs (III), were synthesized and structurally characterized. The compounds differ from each other in the structural organization. The Np central atom in [NpO₄(OH)₂]^3– anions has oxygen surrounding in the form of a tetragonal bipyramid with the O atoms of hydroxide ions in the apical positions. The hydrated Na⁺ cations have oxygen surrounding in the form of a distorted octahedron. In the structure of I, there are two independent Rb cations with 10- and 12-vertex coordination polyhedra, and in the structures of II and III the framework of large cations is built of 12-vertex Rb and Cs polyhedra. The coordination polyhedra of the Np and Na atoms, sharing a common edge (I, III), or chains of the coordination polyhedra of the Np and Na atoms, sharing common vertices (II), are accommodated in the channels of the frameworks. Hydrogen bonds influence the crystal packing and the geometric characteristics of the [NpO₄(OH)₂]^3– anions.

Qualitative studies were performed, and the feasibility of ethanol fluorination by its reactions with anhydrous HF and UF₆ was demonstrated. The reaction occurs at temperatures of up to 150°С via replacement of OH groups with probable formation of Freon 161 and substitution of СH groups with the most probable formation of Freon 152. The Freons were identified by IR spectroscopy. The solid reaction products mainly consist of intermediate uranium fluorides. The formation of uranyl fluoride is not proved unambiguously.

The ability of sodium nitrate/urea mixture in the presence of tetrahydrofuran to enhance the purity of uranium produced from crude yellowcake with the subsequent preparation of different forms of highly pure uranium oxides (UO₄·4H₂O, U₃O₈, UO₃) was examined. The methods of X-ray fluorescence, X-ray diffraction, and energy-dispersive X-ray analysis and inductively coupled plasma optical emission spectrometry were used. The highest uranium purity was reached using 1 M NaNO₃ + 1 or 2 M urea. The uranium loss from the crude yellowcake was insignificant.

Problems of choosing a model for describing empirical sorption data in a system consisting of an energetically nonuniform sorbent and a chemically uniform sorbate in the case when the distribution of energetically nonuniform sorption sites in the material is unknown a priori are considered. The advantages and drawbacks of choosing a sorption model adequate to the experimental data on the basis of analysis of variance are analyzed taking into account the estimated boundaries of the minimum necessary accuracy of the primary experimental data. Statistical methods do not always allow unambiguous choice of an adequate model because of limited accuracy of the experimental data. In such cases, the check of the physicochemical consequences of the model is the best argument in favor of its adequacy.

The ability of a chelating sorbent based on maleic anhydride–styrene copolymer to take up uranium was studied. The sorbent was prepared by modification of the copolymer with Norsulfazolum in the presence of formaldehyde. The dependence of the sorption capacity on the solution acidity was studied. At pH 5, the degree of sorption passes through a maximum. As the uranium concentration in the solution is increased, the amount of the sorbed metal increases, reaching a maximum at a concentration of 8 × 10^–3 M (SC = 1253 mg g^–1). The influence of the solution ionic strength on the uranium sorption was examined. The ionic strength of up to 0.4 M does not affect the sorption, but as the ionic strength is increased further, the sorption decreases, first gradually and then sharply. The desorption of the sorbed uranium ions was studied. The effect of mineral and organic acids on the uranium desorption was examined. The desorption is maximal with HClO₄.

A method for preparing ^99mTc-Dacarbazine, a potential cancer diagnostic agent, was developed. The method is based on direct labeling of Dacarbazine with ^99mTc in the presence of stannous chloride as reducing agent. The reaction conditions were optimized to obtain the radiochemical yield of ^99mTc-Dacarbazine higher than 90%. The biodistribution of ^99mTc-Dacarbazine in normal and tumor-bearing Albino Swiss mice was studied. ^99mTc-Dacarbazine has a high tumor affinity and shows promise for cancer imaging. Quantitative relationship between the optimized structures and computed molecular properties related to Dacarbazine binding sites was analyzed using molecular modeling.