Decontamination of radioactive cesium from natural NaCl by amide-type open-chain crown ethers

An attempt has been made to develop a radiochemical methodology for the decontamination of a trace amount of radioactive cesium from a bulk amount of natural NaCl by liquid-liquid extraction (LLX). Open chain crown ethers, of amide type, namely, N,N,N",N"-tetraphenyl-3,6-dioxaoctanediamide (TDD), N,N,N",N"-tetraphenyl-3,6,9-trioxaundecanediamide and N,N"-dinaphthyl-N,N"-diphenyl-3,6-dioxaoctanediamide (DDD) have been chosen for this purpose. The separation factor between Cs and Na is the highest when 10^-4M TDD dissolved in nitrobenzene is used as extractant and 0.4M picric acid at pH 5.0 is used as aqueous phase. About 60% Cs is extracted in this condition in a single run.     

Decontamination of radioactive cesium in natural NaCl by amide-type open-chain crown ethers(II)

A series of UO₂ ²⁺ complex with monoamide ligand was isolated. The complexes have been characterized with the aid of ¹³C and ¹HNMR spectroscopic studies. The result shows that the amide ligand directly coordinates to the uranyl(VI) ion through its carbonyl group. The change of the value of the chemical shift due to the complexation has been discussed.     

Decontamination of spent ion-exchange resins contaminated with cesium radionuclides

Possible causes of the occurrence of radioactive contamination irremovable by acid–base regeneration of ion-exchange resins used in treatment of process media and liquid radioactive waste have been studied. It has been found that most of the irremovable cesium radionuclides are bound to inorganic deposits on the surface and in the bulk of ion-exchange resin granules. The nature of inorganic inclusions has been investigated on real and model spent ion-exchange resins (SIER). A method has been proposed for decontaminating SIER using resorcinol–formaldehyde resins selective to cesium radionuclides. Such an approach has been shown to be promising for deep decontamination of SIER.     

Calculation of dose conversion coefficients for radioactive cesium in contaminated soil by depth and density

Journal of Radioanalytical and Nuclear Chemistry - Radiation dose to personnel on the ground contaminated with radioactive cesium after nuclear power plant accident depends on cesium activity,...     

Dietary intakes of radioactive cesium for Ukrainians

Daily intakes of ¹³⁴Cs and ¹³⁷Cs in Ukrainians were estimated in relation to the health effects on habitants after the Chernobyl accident. Two hundred and sixty-eight diet samples were collected from 25 oblasts (regions) using a duplicate portion method. For Ukrainians, the range and median daily intakes of ¹³⁷Cs were 0.53–571 and 8.8 Bq per person, respectively. Intakes of ¹³⁴Cs were also detected in highly ¹³⁷Cs contaminated areas. Daily intakes of ¹³⁴Cs were in the range of not detected to 3.6 Bq per person. Using the highest radiocesium intakes, annual effective doses for ¹³⁴Cs and ¹³⁷Cs were estimated to be 2.5·10⁻² and 2.7 mSv, respectively.     

Decontamination of radioactive liquid wastes by hydrophytic vegetal organisms

This paper deals with the bioaccumulation of some radioactive ions from contaminated waste solutions, on hydrophytic vegetal organisms. In order to follow the distribution of radioactive ions ¹³⁷Cs⁺, ⁶⁰Co²⁺ and ⁵¹Cr³⁺ in various cell components extracted from Spirulina platensis, Porphiridium cruentum, Scenedesmus quadricauda, Lemna minor,Elodea canadensis, Pistia stratiotes and Riccia fluitans, the plants were cultivated in radioactive solutions. The resulting complexes were extracted with acetone or acetic acid and separated chromatographically. The results show an intense activity of the polysaccharide and lipoid fractions in the bioaccumulation process. The bioaccumulation varies in the series: Spirulina>Scenedesmus>Porphiridium>Riccia>Pistia> Lemna ³ Elodea for ¹³⁷Cs⁺ and ⁶⁰Co²⁺; Spirulina>Porphiridium>Scenedesmus>Riccia>Pistia>Lemna>Elodea for ⁵¹Cr³⁺.     

Decontamination of some radioactive effluents by means of ceramic filters

The paper deals with the use of some ceramic materials for the removal of⁵⁵⁺⁵⁹Fe³⁺ and⁶⁰Co²⁺ ions from residual waters. For this purpose, chamotte powder has been used both by itself or in a mixture with aluminium oxide. The pastes obtained by wetting these materials have been shaped in the form of crucibles. The radioactive ions which exist in residual effluents, have been retained to a large extent on these filters. Separately, the leaching of radioactive ions previously retained on the filtering mass, has been studied under the influence of water and of diluted solutions of hydrochloric acid or sodium chloride.     

Recovery of cesium from intermediate level liquid radioactive waste

The antioxidant Lowinox 22M46 (Naftonox 22M46) were used for the extraction of cesium from intermediate level liquid radioactive wastes.     

Decontamination of radioactive waste fission products by treated natural clays

The removal of carrier free long living fission products as iodine-131, strontium-90 and cesium-137 by treated local clays is successfully achieved with large capacity. Iodine-131 which is difficultly adsorbed has been removed completely by silver treated phosphate clay. Strontium-90 and cesium-137 by adequately heat treating the clays have been almost removed. Results of column experiments agree well with our batch experiments.     

Composite CFC-PU foam ion exchanger in the removal of radioactive cesium

The LabSOCS software performs mathematical efficiency calibration of Ge detectors. Extensive tests have been conducted comparing the LabSOCS efficiency calibration with those from traditional radioactive sources for typical laboratory geometries. For this study, 4 NIST-traceable standards containing 13 different energy lines were counted in 7 different geometries that are typical of laboratory samples. The results from the first 13 detectors produced using this process show that efficiency calibrations generated with LabSOCS have an accuracy of 5.1% SD at low energies and 4.2% SD at high energies.     

Decontamination of oil-polluted soil by cloud point extraction

An extraction procedure based on cloud point phase separation of nonionic surfactants was used to remove oil contamination from soils. The detergent employed was Triton X-114, and its clouding behavior was monitored by means of a fluorescence probe. Changes in the I (1)I (3) ratio of pyrene indicated gradual dehydration of the detergent micelles upon heating. The rate of phase separation, and the volume and water content of the micellar phase were determined. In the practical clean-up, 85-98% of the oil present in the soil was found to enter the micellar phase of the separated washing liquid. A 15-min washing time with 3-5% detergent was found to be sufficient for this degree of contaminant removal from soil containing 0.009-0.017% oil, using a liquid:solid ratio of 5:2. The extraction efficiency decreased with increasing carbon content of the soil. The process holds promise for large-scale treatment of oil-polluted soils.     

Uptake of cesium and strontium by crystalline silicotitanates from radioactive wastes

Crystalline silicotitanate inorganic ion exchanger, with a sitinakite structure is candidate material for remediation of aqueous nuclear waste streams. The syntheses of crystalline silicotitanate (CST) and Nb-substituted crystalline silcotitanate (Nb-CST) were carried out under hydrothermal conditions and the products were characterized using techniques viz., XRD, SEM/EDS, DTA/TGA, surface area respectively. Batch experiments were carried out to study the kinetics of uptake of ¹³⁷Cs and ⁹⁰Sr, to estimate the decontamination factor (DF) values and distribution coefficients (K _d) for the above synthesized CST and Nb-CST samples from actual radioactive waste solutions. The DF values for uptake of Cs and Sr by Nb-CST after 24 h of equilibration was 355 and 136 whereas for CST it was found to be 40 and 176 respectively. The K _d values for uptake of Cs and Sr for Nb-CST after 24 h of equilibration was found to be 35,490 and 13,500 mL/g respectively whereas the K _d values for uptake of Cs and Sr for CST was found to be 4,025 and 17,525 mL/g respectively. The ion exchange capacity of Nb-CST towards ⁹⁰Sr and ¹³⁷Cs was estimated to be 11.8 and 3.2 meq/g respectively whereas the ion exchange capacity of CST towards ⁹⁰Sr and ¹³⁷Cs was estimated to be 14.6 and 4.4 meq/g respectively.     

Sorption of phenol and radioactive cesium onto surfactant modified insolubilized humic acid

In this study, the sorption behavior of two important contaminants, phenol and radioactive cesium (¹³⁷Cs), onto surfactant modified insolubilized humic acid (SMIA) were investigated as a function of time, sorbate concentration utilizing the radiotracer method and UV–Vis spectroscopy. Phenol sorption process was well described by both Freundlich and Tempkin type isotherms, and cesium sorption was described by Freundlich and Dubinin–Radushkevich isotherms. It was found that SMIA adsorbs both cations and phenolic substances. Kinetic studies indicated that adsorption behavior of phenol obey the pseudo second order rate law. FTIR spectroscopic technique was used to understand the structural changes during modification process with surfactants.     

Simulation of radioactive decay by barium substitution for cesium in sodium aluminum-iron phosphate glass

Simulation of ¹³⁷Cs radioactive decay to ¹³⁷Ba by an equiatomic substitution of Cs with Ba in a 30 Na₂O, 10 Cs₂O, 10 Al₂O₃, 10 Fe₂O₃, 40 P₂O₅ (mol%) glass was studied by X-ray diffraction, scanning electron microscopy, Fourier Transform Infrared spectroscopy, Mössbauer spectroscopy, and measurement of hydrolytic durability. Gradual Ba substitution for Cs yielded minor changes in the structural network but did not offer appreciable effect on phase composition and hydrolytic durability of the glasses.

     

Sorption of heavy-metal ions and radioactive cesium by “Ultrasorb” composite sorbent

Data are given on the sorption of heavy-metal ions (Fe³⁺, Co²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cu²⁺ and Ni²⁺) and radioactive isotope¹³⁷Cs from Ringer salt solution by Ultrasorb composite sorbent, which has two components: the modified clay mineral palygorskite (palygorskite-M) and a modified fibrous carbon sorbent of AUT-M type (UVM-Ts). Selectivity series have been determined for the sorption of these toxic metals on the basis of the calculated distribution coefficients K_d under standard conditions. It is shown that the properties of the components combine well in the material, and it is proposed for use as a treatment agent (enterosorbent) having a selective action in the treatment of diseases due to the accumulation of heavy metals and radionuclides in the body. Institute for Sorption and Endoecological Problems, National Academy of Sciences of Ukraine, 13 ul. Generala Naumova, Kiev 03164, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 1, pp. 53–57, January–February, 2000.     

Synthesis and characterization of hollandite-type material intended for the specific containment of radioactive cesium

The hollandite Ba₁Cs_0.28Fe_0.82Al_1.46Ti_5.72O₁₆, which has been proposed for the cesium-specific conditioning, can be synthesized either by an alcoxyde or a dry route. In both cases, a two-step protocol is applied, i.e., a calcination at 1000 °C followed by a sintering at 1200 °C. After sintering, both synthetic processes lead to a tetragonal form. According to the X-ray diffraction (XRD) patterns collected at the barium and the cesium K absorption edges, the different positions of these two elements have been evidenced with a more centered position in the oxygen cubic site of the tunnel for Ba than for Cs. On the contrary, after calcination, the two synthetic routes yield different products. The alcoxyde route gives rise to a mixture of the aforementioned Cs- and Ba-containing tetragonal I4/m hollandite, a Cs-only-containing monoclinic I2/m hollandite and an unidentified phase with a weak coherence length containing only Ba. The dry route yields a single tetragonal hollandite material containing Ba and Cs slightly different in composition from the targeted compound.     

放射性废水中铯的去除方法研究进展

随着核工业的发展,放射性废液的去除越来越受到重视。本文介绍了离子交换法、溶剂萃取法、吸附法、膜分离法和化学沉淀法以及组合工艺等放射性废水中铯的去除方法,对每种方法的原理、特点及应用情况进行了评述,对放射性铯去除方法的研究方向和发展趋势进行了展望。本文对于针对不同情况的放射性污染科学选用放射性铯的去除方法具有较大参考价值。