Separation of137Cs and90Sr from mineralizates of biological materials by dicarbolide of cobalt

The distribution of some radionuclides in the course of¹³⁷Cs and⁹⁰Sr extraction and scrubbing between organic and water phase was determined.¹³⁷Cs and⁹⁰Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate] was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique. Single and repeated extraction of⁹⁰Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO₃ were studied. The extraction of⁹⁰Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of¹³⁷Cs followed by the extraction of⁹⁰Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.     

Separation of polar compounds using carbon columns

The objective of this review with 122 references is to provide structure and retention mechanisms of porous graphitic carbon by chromatographic analysis and computational chemical analysis of retention mechanisms. Synthesis methods of porous graphitic carbon are described. Applications for use as matrix for dynamic coating on porous graphitic carbon and direct separation of polar compounds on porous graphitic carbon demonstrated that the physical and chemical stability of graphitic carbons performed in both chromatography and extraction, especially for polar compounds, those are difficult on both silica-based and organic polymer-based packing materials. The disadvantage is difficult desorption of non-polar compounds adsorbed on the surface. The development of 3.5-microm particles improves the separation power of graphitic carbon columns with the high theoretical plate number.     

The removal of Th,Cs and Sr ions from solution using granulated pumice stone

The removal of Sr, Cs, U and Th ions from aqueous solution by means of natural pumice stone was studied using energy dispersive X-ray fluorescence spectroscopy (EDXRF) as an analytical tool. The results indicate the usefulness of pumice powder and the removal efficiency was found to be in order of Th>Sr>Cs ions, which is altered by the pH of the solution.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995.     

Separation of related opiate compounds using capillary electrochromatography

Capillary electrophoretic separations have been investigated for six controlled narcotic analgesic compounds having related structures. Owing to the similar charge-to-mass ratios of these compounds, capillary zone electrophoresis failed to provide a satisfactory separation, whereas a baseline-resolved separation was achieved in 10 min using micellar electrokinetic chromatography. Column efficiencies of 40,000-150,000 plates/m were obtained with a 50 cm long, 50 microm inner diameter (ID) capillary using 50 mM sodium dodecyl sulfate (SDS) in a 50 mM borate solution containing 12% isopropanol. In contrast, separation of this mixture by capillary electrochromatography proved to be significantly superior. The capillary was 15 cm long, with an ID of 75 microm, and was packed with 1.5 microm nonporous octadecyl silica (ODS) particles. The mobile phase consisted of 80% 10 mM tris(hydroxymethyl)aminomethane (Tris) and 20% acetonitrile, and contained 5 mM SDS. A complete separation was obtained in 2.5 min with an efficiency of 250,000-500,000 plates/m.     

Radioanalytical determination of137Cs and89Sr in milk

Separation of Cs, Sr and Ca from their mixture was studied using solvent extraction and ion exchange techniques. More than 90% separation efficiency was achieved for Ca–Sr separation using ion exchange resin (Doulite C-20) while solvent extraction amounted to 88%. A proposed technique for determination of¹³⁷Cs and⁸⁹Sr in milk (after removal of organic matter) showed more than 80% accuracy for⁸⁹Sr determination and more than 90% for¹³⁷Cs determination.     

Migration of134Cs and85Sr in clay materials

Retardation mechanisms of¹³⁴Cs and⁸⁵Sr have been investigated. Batch determination of distribution coefficientK _d have been carried out for various values of factors affecting retardation such as solid-liquid ratio, particle size, composition of solid phase. Various types of bentonites and mixtures of bentonites with sand have been also studied.     

Separation of 137Cs from nuclear waste

Sodium zirconate is one member of a family of new inorganic ion exchange materials which have high affinity for all actinides and fission product cations except for Cs⁺. A combination of cold, tracer and high level liquid waste experiments with sodium zirconate has shown that 70–80 and 80–100% of the Cs⁺ in high level liquid waste remains in solution following batch or column equilibration, respectively. The fact that ¹³⁷Cs can be obtained in relatively pure form permits subsequent conversion directly to an insoluble radiation source. This is of prime importance in areas such as sewage sludge sterilization via γ-ray irradiation.     

Vitrification of Cs and Sr loaded Iranian natural and synthetic zeolites

Summary This study deals with the treatment of Cs⁺and Sr²⁺by using natural clinoptilolite from Ardakan region (Yazd province) of Iran and its relevant zeolite P as well as the vitrification process for immobilizing the Cs and Sr radionuclides in borosilicate glass matrices. The evaluation of various samples was carried out using X-ray techniques (XRF, XRD) as well as atomic absorption spectroscopy (AAS) for leaching experiments.     

Migration of85Sr and137Cs in vertical soil profiles

The vertical distribution of⁸⁵Sr and¹³⁷Cs in undisturbed single-contaminated agricultural soils have been studied during their irrigation with wet atmospheric precipitation in dependence on time under laboratory conditions for about one year. The soil samples were collected from several localities in the environment of nuclear power plants at Dukovany and Jaslovské Bohunice using a special auger. The samples were placed into polyethylene columns of 9 cm in diameter and 20 cm in height. The activity of radionuclides in soil profiles after their separation into single layers were counted by Ge(Li) semiconductor gamma-spectrometry. Based on the exponential depth distribution of radionuclides, the values of their migration parameters as relaxation depth, migration rate and retardation factor were calculated. The influence of the permanent grass cover and of the applied zeolite on the migration parameters of these radionuclides was also investigated. Presented at the Conference “Nukleonika '98”, Prague, Czech Republic, 9–10 September 1998, dedicated to late Professor František Běhounek in honour of his 100th birthday.     

Separation of 90Y from 90Sr using sequential multiple column extraction chromatography

The distribution coefficient measurements on Y(III) and Sr(II) were performed using ditertiarybutyl dicyclohexano 18-crown-6 (Sr-selective resin) and N,N,N′,N′-tetraoctyldiglycolamide (Y-selective resin) in HNO₃, HCl and HClO₄ media. Separation factors (⁹⁰Y/⁹⁰Sr) based on distribution coefficient data suggested that perchloric acid is distinctly better medium as compared to nitric acid/hydrochloric acid. The mechanism of extraction changes with the nature and concentration of acid and is responsible for the high selectivity in perchloric acid medium. Sequential column studies were carried out on tracers (radioactive/stable) employing Sr-selective/Y-selective extraction chromatographic resins as stationary phases. The final elution of ⁹⁰Y was done in 0.01 M EDTA at pH 4.0 which can be used for clinical applications after radiochemical processing.     

Removal of Cs,Sr, U and Pu species from simulated nuclear waste effluent using graphene oxide

This article reports the findings from a series of radioactive experimental trials which have examined the sorption properties of graphene oxide focused on four key radionuclides commonly linked to effluent challenges in the nuclear industry—Cs, Sr, U and Pu. Unlike previous experimental studies, simulated effluent waste solutions were utilised with compositions typical of those found at the Sellafield nuclear site, UK. Molecular dynamics simulations were performed in parallel to elucidate the functional groups to which radionuclides preferentially adsorb.     

Selectivity for Cs and Sr in Nb-substituted titanosilicate with sitinakite topology

The 25% niobium substituted crystalline titanosilicate with the composition Na_1.5Nb_0.5Ti_1.5O₃SiO₄·2H₂O (Nb-TS) was synthesized under hydrothermal conditions. Its selectivity for radioactive ¹³⁷Cs and ⁸⁹Sr was compared with the TS, Na₂Ti₂O₃SiO₄·2H₂O, having sitinakite topology. The Nb-TS shows significantly higher uptake value for ¹³⁷Cs but lower for ⁸⁹Sr than the TS. To investigate the origin of selectivity, the ion exchanged Cs⁺ and Sr²⁺ forms with the composition, Cs_xNaH_yNb_0.5Ti_1.5O₃SiO₄·zH₂O (x=0.1, 0.2 and 0.3, x+y=0.5 and z=1-2) and Sr_0.2Na_0.6H_0.5Nb_0.5Ti_1.5O₃SiO₄·H₂O, respectively, were structurally characterized from the X-ray powder diffraction data using the Rietveld refinement technique. Simultaneously the kinetics of ¹³⁷Cs and ⁸⁹Sr uptake was investigated for the Nb^V free and doped samples. While the Cs⁺ and Sr²⁺ exchanged form of Nb-TS and the Cs⁺ exchanged form of TS retain the symmetry of the parent compound, the Sr²⁺ exchanged form of TS undergoes a symmetry change. The differences in the uptake of Cs⁺ and Sr²⁺ result from the different coordination environments of cesium and strontium in the eight-ring channel, that result from various hydration sites in the tunnel. The origin of selectivity appears to arise from the higher coordination number of cesium or strontium. Other effects due to Nb^V substitution are reflected in the increase of both, the a- and c-dimensions and thus the unit cell volume, and the population of water vs. Na⁺ in the channel to charge-balance the Nb⁵⁺↔Ti⁴⁺ substitution.     

Separation of polyphenolic compounds extracted from plant matrices using capillary electrophoresis

Phenolic compounds constitute a large group of secondary plant products whose chemical structure may range from quite simple compounds to highly polymerized substances. The polyphenols content have been investigated in the alcoholic extract of the fruits of three different plants: sweet gale, sea buckthorn, hiprose. The trans-resveratrol content we have studied in roots, stems, leaves and flowers of Japanese knotweed grown in Estonia. Plant material was pre-treated in two different ways: by infusing with methanol and by supercritical fluid extraction with carbon dioxide modified with different alcohols. The relationship between variables (pressure, temperature, modifier amount) and yields are examined. The capillary zone electrophoresis methods were developed for the separation of polyphenolic anti-oxidative compounds. Using both water based borate buffer and acetonitrile based non-aqueous media it was possible to get reliable separation of several polyphenolic compounds. Based on that there has been identified such as flavone, trans-resveratrol, catechin, chlorogenic acid, quercetin and myricetin in plant extracts. Changes in the relative concentrations of trans-resveratrol in different parts of the knotweed have been established.     

肉类制品中微量锶的分离及^87Sr/^86Sr同位素比值测定

利用87Sr/86Sr同位素比值进行生物和古人类源区与迁徙的示踪是Sr同位素技术应用的新领域,也是考古研究和肉类食品溯源研究的新尝试。本研究对牛肉干粉采用酸溶、微波消解和灰化后硝酸提取等不同方法进行消解,比较了它们的离子交换分离效果和Sr同位素测定结果;用石英、石墨和瓷坩埚3种器皿对牛肉干粉进行灰化,检测了灰化器皿对87Sr/86Sr同位素比值的影响,从而确定了石英坩埚灰化的消解方法,建立了适合于肉类制品微量Sr的化学分离方法与87Sr/86Sr同位素比值测定方法。本方法包括肉类制品的石英坩埚灰化、离子交换分离和87Sr/86Sr比值的热离子化质谱测定。所建方法对肉类食品溯源和考古研究等领域富含有机质样品的Sr同位素比值测定具有普适性。     

Separation of two groups of oestrogen mimicking compounds using micellar electrokinetic chromatography

Two groups of compounds are being investigated due to their reported oestrogen mimicking characteristics in the environment. Separation of phenolic compounds and synthetic oestrogens using micellar electrokinetic chromatography is reported. Photodiode array detection is used for both separations. A standard separation buffer can be used for both groups of compounds including zwitterionic buffer cyclohexylamino-1-propanesulfonic acid, 20 mM at pH 11.5. It was found necessary to include 15% acetonitrile and 25 mM sodium dodecyl sulfate to aid separation and maintain analytes in solution. Optimum separations are achieved using 20 kV with hydrodynamic injection for 5 s. The relative standard deviation (RSD) for reproducibility was investigated for a mixture of phenols and synthetic oestrogens. For these compounds RSD was found to be <0.6% in all cases. Peak efficiencies ranged from 76,000 to 150,000 theoretical plates for different analytes. Application to environmental samples is discussed.     

Cs and Sr removal from solution using potassium nickel hexacyanoferrate impregnated zeolites</p> </p>

Summary Potassium nickel hexacyanoferrate, KNiFC, was incorporated in the porous matrix of zeolites by successive impregnation with Ni(NO₃)₂ and</o:p></p> K₄Fe (CN)₆.¹ CFC and PFC exchangers were first prepared by impregnating the potassium nickel hexacyanoferrate into the clinoptilolite and the synthetic P zeolite, respectively. Ion-exchange isotherms and breakthrough curves were plotted. Results showed that the CFC sorbent is suitable for removal of Cs⁺ where PFC is more suitable for Sr²⁺. Negative effect of Na⁺ as a competing ion in these exchangers was less than in the parent zeolites. Isotherm plots fitted the Langmuir equation.</p> </p>     

Simultaneous determination of Cs and Sr in the high level waste by ion-chromatography

A method based on ion-chromatography has been developed for determination of Cs and Sr in high level waste (HLW) without matrix separation. The acidity of HLW (3 M HNO₃) was decreased to 0.01 M by addition of NaOH. Chromatographic separation of Cs⁺ and Sr⁺⁺ in presence of bulk Na⁺ has achieved using methane sulphonic acid as mobile phase in isocratic and gradient mode. The calibration plot was linear for the concentration range of 0.5–12 mg/L for Cs and 0.025–6 mg/L for Sr with regression coefficients close to 1. RSD obtained for Cs and Sr was 1 and 5 % respectively. Detection limit calculated as 3(S/N) was found to be 20 μg/L for Cs and 30 μg/L for Sr. The standard addition procedure was used to validate the developed method. The samples received from PREFRE, Tarapur and WIP, BARC were analyzed by the new method and the results are presented.     

Determination of90Sr and137Cs in mushrooms following the Chernobyl fallout

After the Chernobyl accident high concentrations of radionuclides were found in Sweden in mushrooms and the contents of⁹⁰Sr and¹³⁷Cs were measured. The level of⁹⁰Sr was generally low and, in proportion to¹³⁷Cs, 2–3 orders of magnitude lower than in the fallut. The contents of¹³⁷Cs varied among species and extreme local variations occurred. The ratio¹³⁴Cs/¹³⁷Cs diverged from other biological samples leading to the conclusion that old fallout was involved in the uptake.