Sorption of <Superscript>90</Superscript>Sr and <Superscript>90</Superscript>Y with stable and metastable modifications of calcium carbonate

A comparative study of sorption of ⁹⁰Sr²⁺ and ⁹⁰Y³⁺ cations from aqueous solutions saturated with respect to calcium carbonate on the metastable CaCO₃ modifications (aragonite and vaterite) and also on the stable CaCO₃ modification (calcite) was carried out at 20°C. The sorption of these radionuclides from the solutions containing Sr(NO₃)₂ carrier and without it was studied. Aragonite shows the highest sorption capacity for ⁹⁰Sr²⁺, and these parameters are the lowest for calcite. All the CaCO₃ metastable modifications irreversibly sorb ⁹⁰Sr²⁺ and ⁹⁰Y³⁺ cations and therefore show promise for sorptive decontamination of water from ⁹⁰Sr.     

Cocrystallization of microamounts of <Superscript>137</Superscript>Cs, <Superscript>90</Superscript>Sr,and <Superscript>90</Superscript>Y from aqueous solutions with the solid phase of mixed potassium neodymium ferrocyanide

Cocrystallization of microamounts of ¹³⁷Cs, ⁹⁰Sr, and ⁹⁰Y with the solid phase of mixed potassium neodymium ferrocyanide was studied in relation to the K₄[Fe(CN)₆]: Nd(NO₃)₃ ratio in aqueous solution. At the K₄[Fe(CN)₆]: Nd(NO₃)₃ ratio higher than 2, all the radionuclides studied virtually quantitatively (to 96–99%) cocrystallize with the KNd[Fe(CN)₆]·4H₂O solid matrix. The cocrystallization coefficients D calculated by the Henderson-Krechek equation exceed 10³. Leaching of ¹³⁷Cs and ¹⁵²Eu from the K(¹³⁷Cs)Nd(¹⁵²Eu)· [Fe(CN)₆]·4H₂O solid matrix with water and with aqueous solutions of HNO₃ (0.1 and 1.0 M) and KOH (4.0 M) was studied.     

Application of FIBAN fibrous sorbents to concentrating <Superscript>90</Superscript>Sr from wastewater

Sorption of ⁹⁰Sr on FIBAN fibrous sorbents from wastewaters is studied. The performance of sorbents depends on pH: chelating sorbent FIBAN Kh-1 efficiently sorbs ⁹⁰Sr at pH 5–8, and strongly acidic sorbent FIBAN K-1, at pH 1–3. Strontium is readily desorbed from the sorbents with 2 M HCl. Conditions of sorption of strontium from various acidic wastewaters are optimized. FIBAN K-1 exhibits high sorption efficiency for ⁹⁰Sr and good kinetic characteristics. With this sorbent, about 90% of radiostrontium is recovered in a convenient form from wastewaters of various compositions. Original Russian Text A.A. Shunkevich, V.I. Grachek, I.I. Ugolev, S.V. Matveichuk, 2007, published in Radiokhimiya, 2007, Vol. 49, No. 6, pp. 554–556.     

Coprecipitation of <Superscript>137</Superscript>Cs, <Superscript>90</Superscript>Sr,and <Superscript>90</Superscript>Y from aqueous and organic solutions with triethylenediamine complexes of <Emphasis Type="Italic">d</Emphasis>-element nitrates

Coprecipitation of ¹³⁷Cs, ⁹⁰Sr, and ⁹⁰Y with low-soluble complexes of nitrates of d elements (Cu²⁺, Ni²⁺, Zn²⁺) with triethylenediamine [(CH₂-CH₂)₃N₂] from aqueous and aqueous-organic solutions was studied. ¹³⁷Cs and ⁹⁰Sr do not noticeably coprecipitate with precipitates of complexes of Cu²⁺, Ni²⁺, and Zn²⁺ with (CH₂-CH₂)₃N₂ in water; in the process, the radionuclide recovery into the precipitate phase does not exceed 10%. At the same time, the degree of recovery of ⁹⁰Y reaches 65% depending on the experimental conditions. In C₂H₅OH and CH₃CN containing 9 and 5% H₂O, respectively, ¹³⁷Cs, ⁹⁰Sr, and ⁹⁰Y coprecipitate with the complexes to a greater extent, with the degree of recovery varying from 30 to 97% at the molar ratio M²⁺: (CH₂-CH₂)₃N₂ = 1 : 1.     

Recovery of <Superscript>137</Superscript>Cs and <Superscript>90</Superscript>Sr from wastewater by sorption on finely dispersed minerals under static conditions

The natural minerals clinoptilolite and tripoli were used for sorption treatment of liquid radioactive waste (LRW) to remove ¹³⁷Cs and ⁹⁰Sr. The efficiency of sorption recovery of these radionuclides with finely dispersed mineral sorbents under static conditions was studied in relation to the sorption time, pH, size of mineral granules, sorbent amount, salt content and chemical composition of solutions, and number of successive sorption steps. The distribution coefficient of radionuclides between the sorbent and aqueous phase and the sorption capacity of sorbents for radionuclides were determined. It was found that treatment of real salt-containing LRW from the Leipunskii Institute of Energy Physics, State Scientific Center of the Russian Federation, with the natural sorbents decreased their activity by 2–3 orders of magnitude owing to recovery of ¹³⁷Cs and ⁹⁰Sr.     

Distribution of <Superscript>137</Superscript>Cs, <Superscript>90</Superscript>Sr, <Superscript>239 + 240</Superscript>Pu, <Superscript>241</Superscript>Am,and <Superscript>244</Superscript>Cm among Components of Organic Matter of Soils in Near Exclusion Zone of the Chernobyl NPP

Distribution of Chernobyl-derived ¹³⁷Cs, ⁹⁰Sr, ^{239 + 240}Pu, ²⁴¹Am, and ²⁴⁴Cm among organic fractions of soddy-podzolic, sandy, soddy-meadow, and peat soils collected from the Chernobyl Exclusion Zone along the North-Western radioactive fallout track was determined. Regardless of the soil type, 80–85% of ¹³⁷Cs is tightly fixed on the mineral fraction of the soil. Depending on the soil type, 50–70% of ⁹⁰Sr and 15– 45% of ²⁴¹Am are associated with fulvic acid fractions. ²⁴¹Am and ²⁴⁴Cu are similarly distributed among the organic acid fractions. In all the soil types studied, ^{239 + 240}Pu is associated essentially with humic acid fractions. Natural ^{230, 232}Th and technogenic ^{239 + 240}Pu are similarly distributed among the organic fractions.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 91–96.Original Russian Text Copyright © 2005 by Odintsov, Pazukhin, Sazhenyuk.     

Sorption treatment of radioactively contaminated natural waters to remove <Superscript>90</Superscript>Sr and <Superscript>137</Superscript>Cs using bauxites and products of their processing

Sorption treatment of radioactively contaminated natural waters to remove ⁹⁰Sr and ¹³⁷Cs using an alumina production waste, red bauxite slimes, is considered. In radiostrontium sorption, they surpass both the initial bauxite ore (Boksitogorsk deposit) and adjoin rocks (limestone, dolomite, bentonite clay), and owing to porous structure they act as efficient filtering material.     

Isolation of <Superscript>58</Superscript>Co, <Superscript>54</Superscript>Mn,and <Superscript>86</Superscript>Rb from <Superscript>89</Superscript>Sr production wastes

Procedures for isolation of ⁵⁸Co, ⁵⁴Mn, and ⁸⁶Rb from ⁸⁹Sr production wastes are described. The production of ⁸⁹Sr was based on irradiation of natural Y in the form of oxide, placed in 1Cr18Ni10Ti stainless steel ampules, on a BR-10 fast reactor. ⁵⁸Co and ⁵⁴Mn were isolated from the casings of stainless steel ampules, and ⁸⁶Rb, from the tail solution after the isolation of ⁸⁹Sr.     

Intricacies of the Determination of the Radiochemical Purity of <Superscript>68</Superscript>Ga Preparations: Possibility of Sorption of Ionic <Superscript>68</Superscript>Ga Species on Reversed-Phase Columns

The results of studying ⁶⁸Ga radiopharmaceuticals using various TLC and HPLC procedures are compared. The data obtained reliably show that a part of ⁶⁸Ga ionic species are irreversibly (under definite conditions) sorbed onto chromatographic columns packed with С18 reversed phase. The loss of ⁶⁸Ga ionic species in the analysis can reach 90%. The ⁶⁸Ga loss increases with an increase in pH of the preparation. At pH 2.5–3.0, the total loss of ⁶⁸Ga ionic species on the chromatographic column does not exceed 15%. At pH 4.0, it is 65 ± 7% on the average, and at pH 6.0 it reaches 87 ± 8%. This effect should be taken into account in analysis of any ⁶⁸Ga radiopharmaceuticals.     

Effect of complexing anions on sorption of U(VI), <Superscript>90</Superscript>Sr,and <Superscript>90</Superscript>Y 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 K _d 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, K _d 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 (K _d does not exceed 16 ml g⁻¹ at V/m = 50 ml g⁻¹), and on LDH-Mg-Al-CO₃ the sorption sharply decreases (K _d 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, K _d 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.     

Behavior of Microamounts of <Superscript>22</Superscript>Na, <Superscript>85</Superscript>Sr, <Superscript>137</Superscript>Cs,and <Superscript>152</Superscript>Eu in Sorption and Coprecipitation on Mixed Potassium Neodymium Ferrocyanide from Solutions

Sorption of ⁸⁵Sr, ¹³⁷Cs, ²²Na, and ¹⁵²Eu on solid mixed potassium neodymium ferrocyanide KNd[Fe(CN)₆]·4H₂O from neutral, acidic, and alkaline media and also coprecipitation of these radionuclides with KNd[Fe(CN)₆]·4H₂O in its formation from a homogeneous solution were studied. It was found that ⁸⁵Sr and ²²Na do not noticeably coprecipitate with solid KNd[Fe(CN)₆]·4H₂O and are not sorbed by this substance. In aqueous medium, depending on the cesium concentration in solution, from 80 to 98% of ¹³⁷Cs coprecipitates with solid KNd[Fe(CN)₆]·4H₂O. In this case, the distribution coefficient K_d depends on both the cesium concentration in solution and solution pH. Within 30 min of contact of the solid and liquid phases, the degree of recovery of ¹³⁷Cs from aqueous solution with KNd[Fe(CN)₆]·4H₂O is approximately 95.0% of the initial amount. ¹⁵²Eu coprecipitates with solid KNd[Fe(CN)₆]·4H₂O during its formation from a homogeneous solution to 98–99.9%. The degree of recovery of ¹⁵²Eu from aqueous solution with KNd[Fe(CN)₆]·4H₂O precipitate within 60 min of contact of the solid and liquid phases is 70.3% of the initial amount.     

Retrospective estimation of the contamination of Lake Onega with global <Superscript>90</Superscript>Sr and of natural decontamination of its water

The dynamics of the concentration of global ⁹⁰Sr in Lake Onega water for a 40-year period was reconstructed. The natural decontamination of Lake Onega water was characterized by a decrease in the ⁹⁰Sr content with the half-clearance time T = 16.5 years. By the end of formation of the major part of cumulative ⁹⁰Sr inventory in the lake ecosystem (1965), the ⁹⁰Sr inventories in water and bottom media were in 1: 1.2 ratio. By that time, only 55% of the ⁹⁰Sr ingress passed from the lake water to bottom sediments. The water exchange in the lake occurred two times faster than the ⁹⁰Sr clearance. Decelerated natural decontamination of the lake water from ⁹⁰Sr was attributed to buffer properties of the system catchment area-deep lake-river drainage. The annual removal of ⁹⁰Sr from the lake with water of the Svir River was partially compensated by the ⁹⁰Sr supply to the lake from the catchment areas of rivers flowing into the lake. The cumulative inventory of global ⁹⁰Sr in the volume of Lake Onega water during the period from 1964 to 2005 decreased by a factor of ∼5, from 10 to 1.9 TBq.     

Clinoptilolite/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>: a magnetic sorbent for removing <Superscript>90</Superscript>Sr from aqueous media

The ability of a magnetic sorbent prepared by modification of clinoptilolite with magnetite to take up ⁹⁰Sr was studied. ⁹⁰Sr is sorbed most efficiently at pH in the range 6–9. At the sorbent dosage of 5 g dm^–3 and sorption time of 24 h, the degree of ⁹⁰Sr sorption from aqueous solution is as high as 99.8%.     

Determination of the Parameters of Selective <Superscript>137</Superscript>Cs Sorption onto Natural and Ferrocyanide-Modified Glauconite and Clinoptilolite

The effect exerted by surface modification of natural aluminosilicates, glauconite and clinoptilolite, with ferrocyanides on the parameters of selective ¹³⁷Cs sorption was studied. The modification leads to an increase in the specific sorption and in the radiocesium interception potential in the presence of potassium, RIP(K). RIP(K) of the modified sorbents NPF-Gl and NPF-Cl was 6.1 × 10⁵ and 5.0 × 10⁶ mmol kg^–1, and the specific sorption capacity, 138 ± 14 and 136 ± 12 mg g^–1, respectively. The regular trends in variation of the ¹³⁷Cs distribution coefficients in sorption onto the natural and modified sorbents at K⁺ and Са²⁺ concentrations ranging from 10^–4 to 2.0 M were found. The modified sorbents exhibit high specificity to ¹³⁷Cs in a wide range of Ca and K concentrations in the solutions.     

Determination of the content of <Superscript>85</Superscript>Kr and <Superscript>133</Superscript>Xe in air using a krypton-xenon mixture

A procedure was developed for determining radioactive isotopes of Kr and Xe in air using a krypton-xenon mixture (KXM) produced at air separation plants. The procedure allows determination of background volume concentrations of Kr and Xe at long distances from sites of their injection using common spectrometric apparatus. The results of monitoring volume concentrations of ⁸⁵Kr and ¹³³Xe in Cherepovets in 2006–2008 are presented.     

Radiochemical and biological characterization of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc-oxiracetam as a model for brain imaging

^99mTc-oxiracetam was prepared. It can be used as a radiotracer for brain imaging. Under the optimum conditions (0.5 mg of oxiracetam, 50 μg of SnCl₂·2H₂O, pH 7, room temperature, 30 min), the radio-chemical yield determined by chromatographic methods reached 96%. Biodistribution studies with mice showed that the brain uptake of the complex was 5.1% injected dose per gram (% ID/g) at 5 min post injection. In this parameter, the complex surpasses the commercially available ^99mTc-ECD (4.7% ID/g) and ^99mTc-HMPAO (2.25% ID/g).     

Coprecipitation of Trace Amounts of <Superscript>137</Superscript>Cs and <Superscript>85</Superscript>Sr with [Na(18-Crown-6]BPh<Subscript>4</Subscript> from Neutral and Alkaline Solutions

Coprecipitation of ¹³⁷Cs and ⁸⁵Sr with [Na(18-crown-6]BPh₄ solid phase from aqueous, aqueous-ethanolic, and alkaline solutions is studied. ¹³⁷Cs and ⁸⁵Sr cocrystallize with [Na(18-crown-6]BPh₄ from aqueous and aqueous-ethanolic solutions. The cocrystallization coefficients D of ¹³⁷Cs and ⁸⁵Sr from aqueous solutions are 2.6±0.5 and 3.3±0.3, respectively. For aqueous-ethanolic solutions, the corresponding values are 4.4±0.5 and 3.4±0.4. In the alkaline solutions (0.1 and 1 M NaOH), 54–74% of ¹³⁷Cs and 37–51% of ⁸⁵Sr pass into the [Na(18-crown-6]BPh₄ solid phase, depending on the crown ether concentration in the system.__________Translated from Radiokhimiya, Vol. 47, No. 3, 2005, pp. 257–260.Original Russian Text Copyright © 2005 by Kulyukhin, Konovalova, Rumer, Kamenskaya, Mikheev.     

Determination of radiochemical and radionuclide purity of a <Superscript>131</Superscript>I preparation

The radiochemical purity of a ¹³¹I preparation (the iodide fraction) was determined by ascending paper chromatography using a mixture of sodium iodide, sodium iodate, and sodium carbonate as a carrier and aqueous methanol as an eluent. The chromatogram was developed with a scanning β-ray spectrometer. The radiochemical purity of ¹³¹I determined by this procedure was 99.98%. The radionuclide purity of the ¹³¹I preparation was measured on a γ-ray spectrometer with an ultrapure Ge detector. The content of radionuclide impurities estimated from their detection limits in the ¹³¹I preparation isolated from TeO₂ in 3–4 days after its irradiation in a reactor was no more than 0.03%. The ⁷⁵Se content in the preparation aged for 6–7 months (which corresponds to a decrease in the ¹³¹I activity by a factor of 10⁶–10⁷ owing to decay) corresponds to 2 × 10^?6% of the activity by the end of irradiation.     

Development of Diffusion-Thermal Methods for Preparing <Superscript>67</Superscript>Cu and <Superscript>124</Superscript>I for Radionuclide Therapy and Positron Emission Tomography

Diffusion-thermal procedures for preparing ⁶⁷Cu and ¹²⁴I for radionuclide therapy and positron emission tomography are suggested. For these procedures, new cyclotron targets of metallic tantalum were developed, which, when exposed to high irradiation doses, ensure the absence of physicochemical interaction (diffusion, alloying) of materials being activated and final products with the support at high temperatures. The thermal, hydrodynamic, and strength characteristics of zinc and tellurium (elemental Te) cyclotron targets were evaluated. For commercial target assembly of the COSTIS system, the operation parameters of the process for preparing ¹²⁴I from elemental tellurium using the derived beams of IBA Cyclone 18/9 or MGTs- 20 accelerators were determined.     

Removal of <Superscript>90</Superscript>Sr from nitric acid solutions with sorbents based on di-<Emphasis Type="Italic">tert</Emphasis>-butyldicyclohexyl-18-crown-6

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 ⁹⁰Sr on all the synthesized sorbents increases with an increase in the HNO₃ concentration in the range 1–7 M. The most pronounced increase in the sorption occurs with an increase in the HNO₃ concentration to 3 M. The maximal distribution coefficient of ⁹⁰Sr (K _d = 158 cm³ g^–1) is reached for the sorbent based on DTBDCH18C6 and 1-octanol in 7 M HNO₃. Experiments on sorption of weighable amounts of Sr²⁺ 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.