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1.
Sorption of U, Ra, and Th from multicomponent aqueous salt solutions on hydrolyzed wood lignin is studied. The mechanism of radionuclide sorption from saline solutions is suggested on the basis of the results of sequential extraction. 相似文献
2.
Capacity of analcym-containing rock, hydrolytic wood lignin, and sorbents based on oat straw to absorb uranium, radium, and thorium from acid and weakly acid solutions of their salts was studied. Possible sorption mechanisms of radionuclides are considered on the basis of data furnished by IR spectroscopy and method of successive extractions. 相似文献
3.
Journal of Radioanalytical and Nuclear Chemistry - The purpose of this study was to systematically analyze the leaching process of radionuclides from a decommissioned uranium tailings. About 40% of... 相似文献
4.
Summary The paper presents a procedure to prepare soil samples for U and Th isotope measurement by alpha-spectrometry after coprecipitation
with LaF 3. In this procedure the reduction of U(VI) to U(IV) was performed by Zn metal in 4M HCl solution. The recoveries of chemical
separation equal to eU-chemistry = 78±4% for uranium and eTh-chemistry = 82±4% for thorium. Canberra alpha-spectrometer was used with PIPS detectors of A-1200-37-AM Model of 1200 mm 2 active area. The counting efficiency of the measuring system equals to ecounting = 18% and the total efficiencies were eU = ecounting .e U-chemistry = 14.0±0.7% for uranium and eTh = ecounting .e Th-chemistry = 14.7±0.7% for thorium. The recoveries of chemical separation were rather high (about 80%), that leads to the use of a small
weight of soil sample (about 0.5 g). The efficiencies were also stable, that allows analyzing the soil sample without using
radiotracers. They are advantages of the sample preparation procedure of this work. 相似文献
5.
An anion exchanger OSTION AT 0807 of Czechoslovak production was tested for the separation of radium, thorium, uranium and plutonium. According to the results, the separation process is suitable for analysis of atmospheric precipitation samples. Separation efficiency can be increased by the repetition of the procedures. 相似文献
6.
The tantalum (Ta)/niobium (Nb) tailing is the tailing after smelting Ta/Nb ore. The tailing contains a certain amount of radioactive element uranium (U) and thorium (Th). U and Th from Ta/Nb tailing were leached by nitric acid and sulfuric acid. Leaching effect and kinetics were investigated under the conditions of different acid concentration, temperature, liquid–solid ratio and time. The results showed that the leaching effects of sulfuric acid on U and Th were much better than that of nitric acid. Kinetic analysis shows that the leaching of U and Th by nitric acid and sulfuric acid are surface chemical reaction. 相似文献
7.
A manganese dioxide coprecipitation procedure is utilized to replace a time-consuming evaporation step for the extraction
of thorium, uranium and cerium from freshwater samples. The average recovery for 20-liter samples is greater than 95% for 234Th and 144Ce. The data indicate that the manganese dioxide coprecipitation process does not affect the recovery of thorium and uranium
during our routine analytical procedure. 相似文献
8.
The feasibility is discussed of applying different radiation sources for f-radiography, (n, α)-radiography and autoradiography
for the determination of the spatial distribution, and the local and total concentrations of boron, lithium, radium, uranium
and thorium in various materials, achieving high sensitivity and accuracy. Results demonstrating the application of the developed
methods of radiography in geological practice are presented. 相似文献
9.
Biological method was studied for remediation of soil/concrete contaminated with uranium and radium. Optimum experiment conditions for mixing ratios of penatron and soil, and the pH of soil was obtained through several bioremediations with soil contaminated with uranium and radium. It was found that an optimum mixing ratio of penatron for bioremediation of uranium soil was 1 %. Also, the optimum pH condition for bioremediation of soil contaminated with uranium and radium was 7.5. The removal efficiencies of uranium and radium from higher concentration of soil were rather reduced in comparison with those from lower concentration of soil. Meanwhile, the removal of uranium and radium in concrete by bioremediation is possible but the removal rate from concrete was slower than that from soil. The removal efficiencies of uranium and radium from soil under injection of 1 % penatron at pH 7.5 for 120 days were 81.2 and 81.6 %, respectively, and the removal efficiencies of uranium and radium from concrete under the same condition were 63.0 and 45.2 %, respectively. Beyond 30 days, removal rates of uranium and radium from soil and concrete by bioremediation was very slow. 相似文献
10.
Thorium-230 has many research applications, but there is not a commercial source of this isotope. However, since 230Th is part of the 238U decay chain, it can be separated from naturally occurring uranium. In this work, a novel procedure was developed to separate thorium from uranium ore, consisting of leaching, liquid–liquid extraction, precipitations and ion exchange chromatography. The final product was 91.32?±?0.77 mg of thorium with a purity of 99.5?±?1.2 wt%. Of that, 7.65?±?0.10 mg was 230Th and the remainder 232Th. The total yield of 230Th was 71.1?±?5.4%. Ways to improve the yield by further processing the back-extraction solution are suggested. 相似文献
13.
Quantitative and isotopic measurement of actinide elements is required in many circumstances in the nuclear industry. For example, determination of very low levels of these alpha emitters in human urine samples is used to assess the internal committed dose for nuclear workers. Quantifying actinide isotopes in radioactive waste from nuclear processing and nuclear facility decommissioning provides important information for waste management. Accurate determination of the uranium isotopic ratios in reactor fuels provides fuel burnup information. Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of Th, U, and Pu in various samples including urine, nuclear waste, and nuclear fuel in our laboratory. In order to maximize the capability of the technique and ensure quality analyses, ICP-MS was used to analyze samples directly, or after pre-treatment to separate complicated matrices or to concentrate the analyte(s). High-efficiency sample introduction techniques were investigated. Spectral interferences to minor isotopes caused by peak tails and hydride ions of major actinide isotopes were studied in detail using solutions prepared with light and heavy waters. The quality of the isotopic ratio measurement was monitored using standard reference materials. 相似文献
14.
A solvent extraction process is proposed to recover uranium and thorium from the crystal waste solutions of zirconium oxychloride.
The extraction of iron from hydrochloride medium with P350, the extraction of uranium from hydrochloride with N235, and the
extraction of thorium from the mixture solutions of nitric acid and the hydrochloric acid with P350 was investigated. The
optimum extraction conditions were evaluated with synthetic solutions by studying the parameters of extractant concentration
and acidity. The optimum separation conditions for Fe (III) are recognized as 30% P350 and 4.5 to 6.0 M HCl. The optimum extraction
conditions for U (VI) are recognized as 25% N235 and 4.5 to 6.0 M HCl. And the optimum extraction conditions for Th (VI) are
recognized as 30% P350 and 2.5 to 3.5 M HNO 3 in the mixture solutions. The recovery of uranium and thorium from the crystal waste solutions of zirconium oxychloride was
investigated also. The results indicate that the recoveries of uranium and thorium are 92 and 86%, respectively. 相似文献
15.
Acid leaching of uranium deposits is not a selective process. Sulfuric acid solubilizes iron(III) and half or more of the thorium depending on the mineralog of this element. In uranium recovery by solvent extraction process, uranium is separated from iron by an organic phase consisting of 10 vol% tributylphosphate(TBP) in kerosine diluent. Provided that the aqueous phase is saturated with ammonium nitrate or made 4–5 M in nitric acid prior to extraction. Nitric acid or ammonium nitrate is added to the leach solution in order to obtain a uranyl nitrate product. Leach solutions containing thorium(IV) besides iron are treated in an analogous fashion. Uranium can be extracted away from thorium using 10 vol% TBP in kerosine diluent. The aqueous phase should be saturated with ammonium nitrate and the pH of the solution lowered to 0.5 with sufficient amount of sulfuric acid. In other words, the separation of uranium and thorium depends on the way the relative distributions of the two materials between aqueous solutions and TBP vary with sulfuric acid concentration. Thorium is later recovered from the waste leach liquor, after removal of sulfate ions. Uranium can be stripped from the organic phase by distilled water, and precipitated as ammonium diuranate. 相似文献
16.
The affinity of Chelex-100 for radium has been investigated as a function of pH and salinity compared to the Chelex-100 affinity
for uranium to assess possible application of the resin for the selective separation of the two naturally occurring radionuclides
from aqueous solutions. According to the experimental data the maximum chemical recovery of Chelex-100 is observed for uranium
at pH 5 and for radium at pH 3 indicating a pH controlled selectivity of the resin for the two radionuclides. Moreover, the
effect of salinity on the chemical recovery of radium is significant, resulting in a dramatic decrease of the former with
increasing salinity. On the other hand, there is almost no effect of the salinity on the chemical recovery of uranium, indicating
the higher affinity of Chelex-100 for uranium, which could be attributed to the formation of inner-sphere complexes of U(VI)
with the iminoacetic moieties of the resin. The method has been successfully applied for the uranium separation from a radionuclide
mixture. 相似文献
17.
The uptake of 238U and 232Th in different parts of some selected plants used in traditional treatment of hypertension and diabetes in south-eastern
Morocco (Errachidia area) has been studied using two different types of solid state nuclear track detectors (SSNTDs) LR-115
type II and CR-39. Plant uptake of radionuclides is one of many vectors for introduction of contaminants into the human food
chain. Thus, it is critical to understand soil–plant relationships that control nuclide bioavailability. Soil concentrations
of uranium ranged from 6.10 to 11.62 ppm, with a mean of 7.90 ppm. Soil concentrations of thorium ranged from 2.70 to 4.80
ppm, with a mean of 3.41 ppm. Mean uranium specific activities were 8.38 Bq kg −1 in root tissue, 5 Bq kg −1 in stem tissue and 6.02 Bq kg −1 in leaf tissue. Mean thorium specific activities were 2.53 Bq kg −1 in root tissue, 1.64 Bq kg −1 in stem tissue and 1.96 Bq kg −1 in leaf tissue. The transfer factors of 238U and 232Th from soil to different parts (root, stem, leaf, seed and fruit) of studied plant samples have been investigated. The transfer
factors obtained for root plants were markedly higher than those for leaf, stem, fruit and seed plants. Soil-to-plant transfer
factor (TF) is one of the most important parameters to be used in transfer models for predicting the concentration of radionuclides
in agricultural crops and for estimating dose impacts to man. This study of uranium and thorium uptake in plants used in traditional
medicine is also significant as far as the health hazard effects of uranium and thorium in human being are concerned. 相似文献
18.
A sequential extraction procedure was used to study the changes in the physicochemical forms of americium (Am), thorium (Th), and uranium (U) in laboratory-contaminated Chernozem soil as a result of sharp variations of the environmental temperature and soil moisture. The influence of freezing and soil drought on the radio-ecological hazard was evaluated three months after radioactive contamination with aqueous solutions of 241Am, 234Th, and U. The subsequent changes in the physicochemical forms of the actinides, caused by sharp increases in the environmental temperature and soil moisture, were examined for one month. The data showed that continuous freezing increased the potentially mobile forms of Am and Th but had the opposite effect on U. Prolonged soil drought did not influence the fractionation of Am and Th but led to the redistribution of U between the carbonates and organic matter and caused its immobilisation. The sharp increase in the temperature of the frozen soil caused the immobilisation of Am and Th and increased the potential mobility of U. The warming and enhanced humidity of the dry soil led to the immobilisation of Am and redistribution of U between the soil phases. 相似文献
20.
Sand granule are used as a filter bed in many ground water treatment stations to remove particulate matter from untreated water. A build up of radioactivity may take place on the granules. The disposal of those granules poses a significant problem. A batch technique was used to test the possibility of removing radioactivity from actual samples of the loaded sands. The study was limited to combined radium ( 226Ra and 228Ra). Acidity, temperature, contact time and liquid-to-solid ratio were thoroughly investigated as factors affecting the treatment process. The data obtained are discussed on the basis of the experimental results. 相似文献
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