卷 66, 编号 3 (2024)

The properties of H₂O₂ and its reactions with lanthanide and actinide ions are considered. The potential values of pairs involving H₂O₂ in acidic and alkaline solutions are given. Depending on the oxidative potential of the f-element ion and pH, H₂O₂ exhibits oxidizing or reducing properties. The kinetics and mechanisms of reactions of H₂O₂ with lanthanides(II–IV) and with actinides(III–VII) in acidic, carbonate, and alkaline media have been analyzed. Ions of f-elements(III–VI) form peroxide complexes. The peroxo group occupies either one (OOH) or two (OO) coordination sites. U(VI), Np(IV) binds up to 3 peroxo groups. Oxidation or reduction reactions occur intramolecularly. In the case of Yb²⁺, Sm²⁺, U³⁺, Ce⁴⁺ (in an acid solution), Pr(IV) and Am(IV) (in a weakly acidic medium), the bimolecular rate constants are 10⁵–n × 10⁶ L/(mol s), which exceeds the rate of ligand exchange in the coordination sphere of the f-element ion. Therefore, charge transfer occurs in the outer sphere. Coordination spheres of Ce(IV) oxalate, Tb(IV) with $P_2{W}_{17}{O}_{61}^{10-}$, and Np(VI) with Nslow down the charge transfer between H₂O₂ and the f-element ion. H₂O₂ arising during the radiolysis of aqueous solutions is in an excited state and is more active than H₂O₂ introduced from the outside. Of particular interest are the reactions of H₂O₂ with ions of f-elements in strongly complexing or nonaqueous (organic) media, as well as structural studies of solid compounds of peroxides of f-elements.

Two new complex Np(VI) nitrates with carbamoylurea (biuret) and with a derivative of terpyridine (Ph-Terpy) of the composition [(NpO₂)(biuret)(NO₃)₂] (I) and [H₂(Ph-terpy)(NO₃)]₂[NpO₂(NO₃)₄] (II) have been synthesized and structurally characterized. The coordination environment of Np atoms in compounds are distorted hexagonal bipyramids with “yl” oxygen atoms in apical positions. The equatorial plane of the bipyramid in complex I is formed by oxygen atoms of two bidentate NO ₃^– anions and an electroneutral ligand. The equatorial plane of the bipyramid in II is formed by oxygen atoms of two bidentate and two monodentate NO ₃^– anions. The twice protonated Ph-terpy is the basis of the complex cation [H₂(Ph-terpy)(NO₃)]⁺.

The effect of irradiation of a strongly basic vinylpyridine anion exchange resin of the VP–1AP grade in nitrate form on the onset temperatures of exothermic reactions, thermal effects and the composition of gaseous thermolysis products of VP–1AP was studied. It was established that the onset temperatures of exothermic reactions for an irradiated anion exchange resin are reduced by 59–100°C. The total thermal effect of thermolysis of the irradiated sorbent is 67% less than that of the non-irradiated one. An analysis of the composition of the gaseous thermolysis products of the VP–1AP irradiated anion exchange resin showed that at the first stage of thermolysis, the functional groups of the sorbent are predominantly decomposed. At higher temperatures, the process of degradation of the styrene-divinylbenzene anion exchange resin matrix was detected. The significant influence of irradiation on the conditions for the safe use of anion exchange resins during separation of radionuclides from nitric acid solutions was demonstrated.

The results of the sorption of ¹³⁷Cs from the clarified phase of accumulated high-level alkaline radioactive waste from the Mayak Production Association using sorbents based on modified nickel ferrocyanide (Fersal) and resorcinol–formaldehyde resin (RFS-I) in batch and flow conditions are presented. In batch conditions, the distribution coefficient of ¹³⁷Cs on Fersal and RFS-I sorbents is 2300 and 730 cm³/g, respectively. In flow conditions, the volume of the passed solution before the ¹³⁷Cs breakthrough for Fersal and RFS-I sorbents is 140 and 85 column volumes, and the maximum purification factor is 10⁴ and 10³, respectively. To desorb cesium from the Fersal and the RFS-I, 8 mol/dm³ HNO₃ and 1 mol/dm³ HNO₃ solutions, respectively, were used. A decrease in the sorption characteristics of the RFS-I sorbent during the sorption of cesium from high-level alkaline radioactive waste was discovered. A conclusion about the possibility of using the Fersal sorbent for the recovery of ¹³⁷Cs from high-level alkaline radioactive waste from the Mayak Production Association has been made.

¹⁰⁵Rh is one of the promising beta-emitters for therapeutic purposes for nuclear medicine, but its use is limited, among other things, by its low availability, which necessitates the search for new effective ways to obtain it. In this work, the radionuclide composition of a PdCl₂ target irradiated by bremsstrahlung photons is determined and a method is proposed for recovery ¹⁰⁵Rh from it without a carrier using a commercial DGA sorbent, which ensures a high degree of purification of the target isotope. The studies carried out in the future may contribute to the practical use of ¹⁰⁵Rh for nuclear medicine.

Various methods of introducing deuterium into dopamine using isotope exchange are considered. The best result is achieved by isotope exchange with deuterated water at 190°C for 30 min using (a) trifluoroacetic acid as a catalyst and (b) 5% Pd/Al₂O₃ catalyst presaturated with deuterium gas. In the first case, the yield of deuterated dopamine was 65–70%, and the average deuterium content was 2.4–2.5 at./molecule. In the second case, the yield decreased to 35–40%, but the deuterium content increased to 3.50–3.60 at./molecule. The obtained result highlights the effectiveness of an integrated approach to introducing hydrogen isotopes into organic molecules, when activated hydrogen isotope species are formed on the catalyst and the substance deposited on it, which contribute to increasing the efficiency of isotope exchange with deuterated water when heated.