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1.
V. Jedináková J. Cibulková L. Kuča M. Havranová 《Journal of Radioanalytical and Nuclear Chemistry》1979,51(1):47-54
Benzyldimethyldodecylammonium nitrate and benzyltrioctylammonium nitrate were used for the extraction of Am(III) from aqueous
nitrate solutions. The dependence of the extraction performance for Am(III) on the concentration of nitric acid, the kind
and concentration of salting-out agents in the aqueous phase, and the kind of solvent was investigated. Americium is extracted
by the above quarternary salts as a R4NAm(NO3)4 associate. The extraction of Am(III) is compared with the extraction of lanthanides. The high differences in the distribution
coefficients for lanthanides and americium can be utilized for the separation of lanthanides and americium. 相似文献
2.
J. P. Shukla M. S. Nagar M. S. Subramanian 《Journal of Radioanalytical and Nuclear Chemistry》1981,62(1-2):61-72
Solvent extraction behaviour of Am(III) from dilute nitric acid media with sulfoxides (R2SO) in Solvesso-100 has been investigated over a wide range of conditions. Very poor extractability of Am necessitated the
use of salting-out agents, viz., nitrates of Al, Mg, Ca, Li and NH
4
+
. Effects of certain variables such as acidity, extractant concentration, saltingout agent, temperature etc., on metal extraction
by sulfoxides have been examined systematically. For a fixed sulfoxide concentration, extraction attains a maximum value up
to around 0.2–0.4M HNO3 and decreasing above 1M HNO3. In contrast, increasing the concentration of sulfoxide (0.8M DISO, 1.3M DBuSO) gives almost quantitative Am extraction up
to 1M HNO3. For satisfactory extraction, di-n-octyl as well as di-n-hexyl sulfoxide are the most suitable extracting agents. Extractability
of Am increases with increasing amounts of all the salting-out agents studied and their effect follows the sequence: Al3+>Mg2+>Ca2+>Li+>NH
4
+
; this is also the relative dehydrating effect of the cations. The species extracted would appear to be Am(NO3)3.3R2SO. Americium is easily stripped with 1–3M HNO3 solutions from the loaded organic phase. Extraction decreases with increasing temperature, indicating the extraction to be
exothermic. Extraction from partially non-aqueous solutions was also investigated. 相似文献
3.
D. R. Prabhu G. R. Mahajan M. S. Murali J. P. Shukla G. M. Nair P. R. Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》1992,162(1):91-97
The liquid-liquid extraction behavior of plutonium(IV) from aqueous nitric acid media into n-dodecane by di(2-ethylhexyl)sulfoxide (DEHSO) was investigated over a wide range of conditions. Optimum-parameters such as the aqueous phase acidity, reagent and metal concentrations, etc., were established for efficient extraction-separation of tracer as well as macro levels of plutonium. It was found that the extraction increased with increasing nitric acid concentration up to 6M HNO3 and then decreased. Extraction also increased with increasing extractant concentration. After loading of the organic phase with 2 to 50 mg/ml of U(VI), extractability of Pu(IV) became considerably lower. Recovery of Pu(IV) from the organic phase was accomplished using dilute uranium(IV) nitrate as the strippant. 相似文献
4.
Nandita Panda Nihar Bala Devi Sujata Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(3):1205-1211
The extraction of Nd(III) using binary mixtures of Cyanex 272 (HA), Cyanex 921/Cyanex 923 (B) in kerosene from nitric acid medium has been investigated. The effect of aqueous phase acidity, extractant concentration, nitrate ion concentration and diluents on the extraction of Nd(III) has been studied. On the basis of slope analysis results, extracted species are proposed as Nd(NO3)A2·3HA and Nd(NO3)2·A·3HA·B using Cyanex 272 and its mixture with Cyanex 921/Cyanex 923, respectively. With the mixture of 0.1 M Cyanex 272 and 0.1 M Cyanex 923 in kerosene, the extraction of 0.001 M Nd(III) from 0.001 M HNO3 solution was found to be 83.3 % whereas it was 73.3 % when 0.1 M Cyanex 921 used as synergist under same experimental conditions. The stripping data of Nd(III) from the loaded organic phase containing 0.1 M Cyanex 272 and 0.1 M Cyanex 921/Cyanex 923 with different acids indicated sulphuric acid to be the best stripping agent. 相似文献
5.
M. Lal 《Journal of Radioanalytical and Nuclear Chemistry》1985,90(1):105-112
The separation of the trivalent metal ions Am(III) and Eu(III) by extraction chromatography employing TBP impregnated macroporous XAD-4 resin as the stationary phase was examined; some parameters affecting the distribution ratio (Kd) and the column resolution (Rs) of Am(III) and Eu(III) were investigated. These parameters are the effect of TBP loading, aqueous nitrate concentrations, and flow rate. Both Kd andRs increase with the TBP loading. 相似文献
6.
The extraction of Am, Eu, Ce(III), Zr(IV), and Sr from aqueous nitric acid— nitrate media by dibutyl N,N-diethylcarbamylphosphonate
and dibutyl N,N-diethylcar-bamylmethylenephosphonate dissolved in carbon tetrachloride was studied. The trivalent actinide
and lanthanide elements may be separated in certain aqueous phase acidity regions from Fe(III), Zr(IV), and Sr, whereas the
separation of actinide elements from the lanthanide elements is poor. The extractant to metal ratio in the extracted complexes
of Am, Eu, and Ce(III) is 3. The interferences in the extraction due to acidic impurities in the extracting agent are discussed. 相似文献
7.
V. Jedináková L. Kuča M. Vojtíšková 《Journal of Radioanalytical and Nuclear Chemistry》1980,59(1):125-132
We have investigated the effect of coextraction of lanthanides and yttrium on the distribution coefficients DAm in the extraction of americium by benzyldimethyldodecylammonium nitrate (BDMLNNO3) from nitrate solutions. In the coextraction of lanthanides, the extraction of Am(NO3)3 is suppressed, which is markedly manifested in the extraction of light lanthanides (La, Ce, Pr); of the series of lanthanides their extraction is the highest. The effect of nitric acid and the possibility of separation of lanthanides and americium by the application of three-stage multiple extraction is discussed. 相似文献
8.
V. Jedináková J. Cibulková J. Teplý 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(1):69-77
Previously it was found that in the extraction separation on lanthanides and americium from acidic nitrate solutions of nuclear fission products, benzyldimethyldodecylammonium nitrate gives high values of separation coefficients. The change in the extraction capacity of this agent and its solutions in benzene in the extraction of Eu(III) and Am(III) was investigated as a function of the adsorbed dose of ionizing radiation. The slight reduction in the extraction of both metals is caused mainly by the radiolysis products of nitric acid in the organic phase that enter into secondary reactions with both the solvent and the extractant. Comparison of the radiation stability of benzyldimethyldodecylammonium nitrate systems with tertiary amines show that the changes in distribution coefficients in the range of investigated absorbed doses are significantly lower in the former case. The investigated system may be characterized as radiation stable up to about 100 kGy even in the presence of nitric acid. 相似文献
9.
V. K. Manchanda P. K. Mohapatra 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(2):121-130
Complexation of Am(III) with a tris-bipyridine cryptand (L) has been carried out in a nonaqueous medium (CH3CN–CHCl3). Subsequently the complexation behaviour was investigated using the reverse extraction tracer technique with dinonyl naphthalenesulphonic acid (HD) in toluene as the organic phase and varying concentration of HCl (upto 2M) as the aqueous phase. Equilibrium is attained in the two-phase system at a rate dependent on the hydrogen ion concentration in the aqueous phase. Whereas it takes only a few minutes to attain the equilibrium state at pH 6.0, a phase contact period of 50 days was insufficient if the acidity is greater than 0.4M, presumably due to the slow dissociation of the cryptate formed. The large enhancement in the distribution ratio value in the synergistic system with 1M HCl as the aqueous phase under non-equilibrium conditions is employed for the analytical separation of Am(III) from Eu(III). 相似文献
10.
Recycling americium from spent fuels is an important consideration for the future nuclear fuel cycle, as americium is the main contributor to the long-term radiotoxicity and heat power of the final waste, after separation of uranium and plutonium using the PUREX process. The separation of americium alone from a PUREX raffinate can be achieved by co-extracting lanthanide (Ln(III)) and actinide (An(III)) cations into an organic phase containing the diglycolamide extractant TODGA, and then stripping Am(III) with selectivity towards Cm(III) and lanthanides. The water soluble ligand H4TPAEN was tested to selectively strip Am from a loaded organic phase.Based on experimental data obtained by Jülich, NNL and CEA laboratories since 2013, a phenomenological model has been developed to simulate the behavior of americium, curium and lanthanides during their extraction by TODGA and their complexation by H4TPAEN (complex stoichiometry, extraction and complexation constants, kinetics). The model was gradually implemented in the PAREX code and helped to narrow down the best operating conditions. Thus, the following modifications of initial operating conditions were proposed:
- •An increase in the concentration of TPAEN as much as the solubility limit allows.
- •An improvement of the lanthanide scrubbing from the americium flow by adding nitrates to the aqueous phase.
11.
K. Dasthaiah B. Robert Selvan A. S. Suneesh K. A. Venkatesan M. P. Antony R. L. Gardas 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(3):515-521
The imidazolium bis(2-ethylhexyl) phosphate moiety was chemically attached on silica gel by chemical modification. The resulting product ([SG-Im]+ [DEHP]?) was characterized by FT-IR spectroscopy, thermogravimetry and elemental analysis. The sorption behavior of Am(III) and Eu(III) on [SG-Im]+ [DEHP]? was studied from dilute nitric acid medium for the separation of Am(III) and Eu(III) from aqueous waste. The effect of time, concentrations of nitric acid and europium in aqueous phase on the distribution coefficient (K d) was studied. The study indicated the possibility of using modified silica for the separation of Eu(III) from Am(III) with high separation factors (>50 at 0.1 M HNO3). 相似文献
12.
《中国化学快报》2022,33(7):3429-3434
Separation of the minor actinides (Am and Cm) from lanthanides in high-level liquid wastes (HLLW) is one of the most challenging chemical separation tasks known owing to their chemical similarities and is highly significant in nuclear fuel reprocessing plants because it could practically lead to sustainable nuclear energy by closing the nuclear fuel cycle. The solid phase extraction is proposed to be a possible strategy but all reported sorbent materials severely suffer from limited stability and/or efficiency caused by the harsh conditions of high acidity coupled with intense irradiation. Herein, a phenanthroline-based polymeric organic framework (PhenTAPB-POF) was designed and tested for the separation of trivalent americium from lanthanides for the first time. Due to its fully conjugated structure, PhenTAPB-POF exhibits previously unachieved stability under the combined extreme conditions of strong acids and high irradiation field. The americium partitioning experiment indicates that PhenTAPB-POF possesses an ultrahigh adsorption selectivity towards Am(III) over lanthanides (e.g., SFAm(III)/Eu(III) = 3326) in highly acidic simulated HLLW and relatively fast adsorption kinetics in both static and dynamic experiments. Am(III) can be almost quantitatively eluted from the PhenTAPB-POF packed-column using a concentrated nitric acid elution. The high stability and superior separation performance endow PhenTAPB-POF with the promising alternative for separating minor actinides over lanthanides from highly acidic HLLW streams. 相似文献
13.
The extraction of cations of a series of alkali and alkali-earth metals, along with Pb(II), Rh(III), and Pd(II) with crown,
thiacrown and azacrown ethers from picric and nitric acid solutions was studied. Upon the extraction of metal cations with
macrocyclic extractants, the interference of those cations on the extraction of one another was observed in polar solvents.
The causes of this phenomenon are revealed, and a mechanism for the suppression of extraction of the microcomponent with the
macrocomponent is proposed. Upon the simultaneous extraction of americium (III) and europium (III) with calixarenes the co-extraction
was noted for the first time, resulting in the good extraction of Am(III) from nitric acid solutions. We hypothesize on the
formation of a mixed nitrate complex of americium and europium that can be effectively extracted into an organic phase with
calixarenes. 相似文献
14.
O. M. Petrukhin B. Ya. Spivakov V. P. Morgalyuk G. I. Malofeeva E. V. Kuzovkina A. P. Novikov 《Russian Journal of Inorganic Chemistry》2011,56(11):1839-1846
The recovery and separation of plutonium(IV) and americium(III) by solid-phase extraction (SPE) on alkylated silica gel S16
modified with N-benzoylphenylhydroxylamine (BPHA) and with its derivatives was studied. BPHA was modified by introducing into the p-position of the phenyl ring of electronactive substituents that differ in their hydrophobicity: CH3, Ph, Cl, F, and NO2. The SPE of plutonium(IV) and americium(III) was studied in the range of acidities from pH 8 to 1 M HNO3. The recovery and separation of these elements was shown to depend on the nature of the substituent, aqueous acidity, and
the preparation of S16 to SPE experiments. 相似文献
15.
V. Jedináková J. Cibulková J. Teplý M. Novák J. Žilková 《Journal of Radioanalytical and Nuclear Chemistry》1979,51(2):355-362
The radiation stability was investigated of organic phases containing tertiary benzyldialkylamines and quaternary benzyltrialkylammonium
salts which are sultable for the separation of lanthanides and americium from irradiated nuclear fuel. Attention was paid
to changes of the extraction properties in Eu(III) and Am(III) extraction. The influence of the individual components forming
the organic phase (extractant, solvent, solubilizer and nitric acid) on the decrease of the extraction capacity of the organic
phase after irradiation is discussed. The greatest changes in the distribution coefficients DEu and DAm after irradiation were shown for extraction in the presence of nitric acid. As regards the absorbed dose, these systems can
be considered as stable in comparison with organophosphorus extractans. 相似文献
16.
The distribution of uranium(IV) between aqueous nitric acid solutions and solutions of the nitrate salt of the primary amine
Primene JM-T in various diluents is described. The influence of the concentration of the acid, nitrate and perchlorate in
the aqueous phase is studied, taking into account the complex composition of uranium(IV) in the aqueous phase and the acid
content of the organic phase. The uranium(IV) extraction may be explained by the competition between metal complex and nitric
acid for the extracting agent. The absorption spectra of the organic phase and the results of maximum loading experiments
indicate that the uranium(IV) species in the organic phase is the bis-alkylammonium-hexanitrato-uranium(IV) complex [(RNH3)2U(NO3)6].
相似文献
17.
As part of the 2006 French Act on sustainable radioactive waste and waste management, CEA has been developing a process, (EXAm), in order to separate americium from curium and fission product downstream of COEXTM or PUREX processes. The goal is to recover Am up to 99%. The first step mainly consists of splitting americium from curium thanks to the diamide in organic phase combined with a complexing agent in high nitric acid. The low separation factor between Am and Cm leads to a very sensitive process flowsheet towards operating conditions. It is then difficult to manage high recovery yields with good purity. A model has been built taking into account complexation equilibria by TEDGA in aqueous phase and extraction equilibria in organic phase for each element. This model was put into the PAREX code to find the correct flowsheet, and then to conduct sensitivity studies regarding several parameters such as feed flow, acidity, temperature, solvent flow and reagent concentration. These studies have pointed out a high correlation between americium yield and decontamination factor and, also, an equivalence between any change of the most sensitive parameters and a change in TEDGA concentration. A running procedure was followed during two hot tests: the main concept was to start with a less efficient process and then to improve it during the test in order to reach required performances by adjusting the TEDGA flow rate. 相似文献
18.
J. N. Mathur M. S. Murali P. R. Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》1991,152(1):127-135
Extraction of Am(III) by dihexyl N,N-diethylcarbamoylmethyl phosphonate (CMP) in benzene from nitric acid solutions (pH 2.0 to 6.0M) has been studied. High extraction of Am(III) by CMP from 2–3M HNO3 was observed. The species extracted was found to be Am(NO3)3·3CMP. The extraction was also done with mixtures of CMP+TBP and CMP+TOPO, where mixed species were extracted in the organic phase. The back-extraction experiments gave an efficient back-extraction of Am(III) by pH 2.0 (HNO3) from the loaded CMP+TBP phase but a poor back-extraction from the loaded CMP+TOPO phase. The loading of Nd(III) by mixture of CMP and TBP was 50% of the CMP concentrations at a total Nd(III) concentration of 0.182M. The thermodynamic parameters of Am(III) extraction by a mixture of CMP and TBP were evaluated by temperature variation method, which suggests that the two-phase reaction is stabilized by enthalpy and opposed by entropy. 相似文献
19.
《Journal of the Less Common Metals》1985,105(2):255-261
The distribution of lanthanum(III) between aqueous H2SO4 solutions and Primene JMT in the organic phase is described. The dependence of the extraction on acidity, extractant concentration and type of diluent was investigated. Aggregation numbers are calculated and a mechanism for the extraction is suggested. The separation of thorium(IV) from lanthanum(III), cerium(III) and cerium(IV) is outlined. 相似文献
20.
B. F. Myasoedov A. P. Novikov M. S. Mil Yukova M. N. Mikheeva T. V. Bunina 《Journal of Radioanalytical and Nuclear Chemistry》1990,142(2):481-487
The stability of emulsions, containing tri-n-octylamine and di-n-octylamine salts in the organic phase and nitric acid in the aqueous phase has been studied. Optimal conditions for the extraction of Am(III) and Am(IV) phosphorus tungstate complexes with such emulsions have been determined. Emulsion membrane extraction is shown to be more effective for this purpose than conventional liquid extraction. 相似文献