N. A. Konovalova

Sorption of radioiodine from aqueous solutions on layered double magnesium aluminum hydroxides at 300 K

Sorption of 131I− and 131IO3− from aqueous solutions at 300 K on solid layered double magnesium aluminum hydroxides (Mg-Al-LDH) in the carbonate (Mg-Al-LDH-CO3) and nitrate (Mg-Al-LDH-NO3) forms was studied. The distribution coefficients of 131I− and 131IO3− between solid Mg-Al-LDH-CO3 and an aqueous solution after contact of these phases for 60 min are 38 and 34 ml g−1, respectively. The distribution coefficients of 131I− and 131IO3− between solid Mg-Al-LDH-NO3 and an aqueous solution, measured under the similar conditions, are about 5 ml g−1. After contact of the solid and liquid phases for 14 h, the distribution coefficients of 131I− and 131IO3− between an aqueous phase and solid layered double magnesium aluminum oxides (Mg-Al-LDO) prepared by thermolysis of Mg-Al-LDH are 7999 and 7068 ml g−1, respectively.

Chemistry of radioactive iodine in aqueous media: Basic and applied aspects

The results of studies on chemistry of radioactive iodine in aqueous media of various compositions, performed in the world in the past decade, are systematized and analyzed. Prospects for using the data obtained in various fields of nuclear power engineering are assessed.

Gas-phase conversion of the U, Sr, Mo, and Zr oxides into water-soluble compounds in the NO x –H2O (vapor)–air atmosphere

The gas-phase conversion of U3O8, MoO3, SrO, and their mechanical mixtures, and also of ZrO2 into water-soluble compounds in the NOx–H2O (vapor)–air atmosphere was studied. In the course of gas-phase conversion, U3O8 and SrO transform into water-soluble compounds (nitrates, hydroxonitrates), whereas MoO3 and ZrO2 undergo no changes. The principal possibility of separating U from Mo and Zr by gas-phase conversion of the oxides in the NOx–H2O (vapor)–air atmosphere was demonstrated.

Absorption of molecular radioiodine from the water vapor-air flow

Sorption of 131I2 from the water vapor-air medium on inorganic nanocomposite materials was studied. All the nanocomposite materials synthesized, containing 1, 2, 4, and 8 wt % Ag in various chemical forms, remove 131I2 from the water vapor-air flow with more than 99% efficiency.

Synthesis of sorbents based on coarsely dispersed silica gel, containing nanoparticles of Ag compounds, for localization of volatile radioactive iodine compounds from the water vapor-air medium

The paper deals with the synthesis and physicochemical properties of sorbents based on coarsely dispersed silica gel, containing 1, 2, 4, and 8 wt % nanoparticles of Ag compounds, intended for localization of volatile radioactive iodine compounds from the water vapor-air medium.

Effect of complexing anions on sorption of U(VI), 90Sr, and 90Y from aqueous solutions on layered double hydroxides of Mg, Al, and Nd

Sorption of 90Sr and 90Y from aqueous solutions on Mg-Al and Mg-Nd layered double hydroxides (LDHs) in various forms was studied. The distribution coefficients Kd of U(VI) and 90Sr on LDH-Mg-Al-EDTA are 100–120 ml g−1 in 15 min of contact of the solid and liquid phases at V/m = 50 ml g−1. At the same time, under similar conditions, U(VI) and 90Sr are not sorbed from aqueous solutions on LDH-Mg-Al-C2O4. The sorption of U(VI) from aqueous solutions containing H2EDTA2−, C2O42−, and CO32− on LDH-Mg-Nd-CO3 and LDH-Mg-Al-CO3 strongly depends on the concentration of the complexing anions in the solution. In particular, for 10−3 M aqueous UO22+ solutions, with an increase in [C2O42−] from 10−3 to 5 × 10−2 M, Kd of U(VI) decreases from >5 × 103 to 70 ml g−1 for LDH-Mg-Al-CO3 and from 170 to ∼0 ml g−1 for LDH-Mg-Nd-CO3. In the presence of 10−3 to 5 × 10−2 M CO32− in aqueous solution, U(VI) is not noticeably sorbed on LDH-Mg-Nd-CO3 (Kd does not exceed 16 ml g−1 at V/m = 50 ml g−1), and on LDH-Mg-Al-CO3 the sorption sharply decreases (Kd decreases from >5 × 103 to ∼0 ml g−1 at V/m = 50 ml g−1). The presence of complexing anions in the solution does not appreciably affect the 90Sr sorption, but noticeably affects the 90Y sorption. With an increase in their concentration, Kd of 90Y appreciably decreases. The effect exerted by Sr2+ ions on the sorption of microamounts of U(VI) and by UO22+ ions on the sorption of microamounts of 90Sr and 90Y from aqueous solutions on LDH-Mg-Nd-CO3 was also examined.

Physicochemical properties of uranium in lower oxidation states

Data on the properties of U in lower oxidation states, published between 1988 to 2005, are summarized. In this period, the interest in the chemistry of trivalent and bivalent uranium, especially in its coordination and organometallic chemistry, considerably increased. Possible applications of trivalent uranium are outlined.

Gas-phase conversion of U, Sr, Mo, and Zr oxides into water-soluble compounds in an HNO3 (vapor)–air atmosphere

Gas-phase conversion of U3O8, MoO3, SrO, ZrO2, and their mechanical mixtures into water-soluble compounds in an HNO3 (vapor)–air atmosphere was studied. In the course of the gas-phase conversion, U3O8 and SrO transform into water-soluble compounds (nitrates, hydroxynitrates), whereas MoO3 and ZrO2 undergo no changes. The principal possibility of separating U from Mo and Zr by gas-phase conversion of the oxides in the HNO3 (vapor)–air atmosphere was demonstrated.

Sorption of CH3131I from the water vapor-air medium onto nanocomposite materials

Sorption of CH3131I from the water vapor-air medium onto inorganic nanocomposite materials containing 1, 2, 4, and 8 wt % Ag in various chemical forms was studied. Despite high ability of the synthesized nanocomposite materials containing 1, 2, and 4 wt % Ag in various chemical forms to take up 131I2 (>99%), they cannot be used for localizing CH3131I from the gas flow. The material containing 8 wt % Ag, namely, the SiO2-8% Ag nanocomposite prepared by treatment of the precursor with a 0.01 M hydroxylamine solution, is the most suitable for this purpose.

Lower Oxidation States of f Elements: III. Properties of Low-Valence Lanthanide and Actinide Compounds in the Solid State and in Various Solvents

Properties of low-valence f-element compounds in the solid state and in protic, aprotic, and mixed solvents are discussed, including the solubility of low-valence f-element compounds, hydration of Ln2+ and An2+, and their complexation in aqueous and organic solutions with various anions (I−, Br−, Cl−, ClO4−, BF4−, BPh4− and polycyclic crown ethers.