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1.
Separations of used nuclear fuel at the engineered scale have generally been completed using the Plutonium Uranium Redox Extraction (PUREX) process. The PUREX process uses tributyl phosphate (TBP) as an extractant to recover uranium and plutonium. While the TBP extractant has proven effective at recovering U and Pu at the engineered scale, TBP is potentially vulnerable to third phase formation and TBP degradation products (monobutyl and dibutyl phosphoric acids) which can complicate recovery of extracted metals from the organic phase. An alternative class of extractants, monoamides, has been considered for applications in thorium and uranium fuel cycles. When compared to TBP, monoamides tend to have higher separation factors for U or Pu from fission products, structural materials, and Th. This review summarizes the literature that explores actinide separations using monoamides by assessing the physiochemical properties between a broader library of branched and straight-chain monoamides than considered in previous reviews. An emphasis is placed on fine-tuning the selectivity of branched monoamides. 相似文献
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Tributylphosphate (TBP), solvent used as extractant for reprocessing spent nuclear fuel, can dimerise under radiolysis. This occurs by radical radical recombination, leading to 10 isomeric dimers (TBP-TBP). These species are complexation agents and are responsible of fission product retention in the organic phase that increases the solvent degradation. In order to limit their formation two free radical inhibitors (In), isopropyl and 1,4-diisopropylbenzenes, were used. These additives reduce by about 50% the concentration of TBP-TBP dimers but this reduction is not strictly followed by TBP regeneration as mixed coupling products from TBP and inhibitor are detected. By using GC-MS-MS and selectively deuterated compounds, the identification of these different isomers (TBP-In) has been realised. From these identifications and from the analysis of the proportion of the different isomers, the major primary TBP radical generated under radiolysis was determined. 相似文献
4.
Biplab Das Shekhar Kumar P. Mondal U. Kamachi Mudali R. Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1161-1171
Red-oil is a mixture of nonspecific composition consisting of extractant, degradation products, nitrated solvent and unidentified
red-coloured nitro-organics. Red-oil formation is coupled with decomposition of extractant and diluent into gases of explosive
nature. If ignited or incinerated, these gases may cause rapid pressurization and endanger the integrity of containment. Such
an event occurred at Tomsk-7 facility in 1993. To ensure safe operation, red-oil formation has to be avoided in the fuel cycle
facilities by a careful combination of several independent measures like strict control over temperature, limiting organic
entrainment in the aqueous streams (which are to be concentrated by evaporation) and control over acidity of aqueous phases.
Since tri-iso amyl phosphate (TiAP) has much lower aqueous solubility as compared to TBP, it is visualized as alternate solvent for PUREX
process. In this work, TiAP red-oil was synthesized and characterized. 相似文献
5.
V. S. Smitha M. Surianarayanan H. Seshadri A. B. Mandal 《Journal of Thermal Analysis and Calorimetry》2013,111(1):849-856
Violent decomposition of Tributyl Phosphate (TBP), a widely employed extractant in the Plutonium Uranium Extraction process of nuclear fueling reprocessing plants in the presence of Nitric acid at temperatures in excess of 130 °C is a matter of concern in serious accidents including in the Savannah River (USA) and Tomsk (Russia). The thermal behavior of TBP under adiabatic conditions employing the world’s benchmark adiabatic calorimeter, the Accelerating Rate Calorimeter is examined. TBP shows multiple self heating exothermic activities with the onset of primary exotherm at 250 °C. The exothermic activity is accompanied by considerable pressure rise. The thermal decomposition of TBP is found to follow first order Arrhenius kinetic model. TBP loses about 70% of its chemical moieties as volatile matter during the exothermic decomposition. Spectroscopic methods are used to elucidate the degradation pathway. 相似文献
6.
Elin Löfström-Engdahl Emma Aneheim Christian Ekberg Hanna Elfverson Mark Foreman Gunnar Skarnemark 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1261-1266
Used nuclear fuel is radiotoxic for mankind and its environment for a long time. However, if it can be transmuted, the radiotoxicity as well as its heat load are reduced. Before a transmutation the actinides within the used fuel need to be separated from the fission, corrosion and activation products. This separation can be achieved by using the liquid–liquid extraction technique. One extraction process that can be used for such a separation is the Group ActiNide EXtraction (GANEX) process. One GANEX process that can successfully accomplish the separation utilizes the diluent cyclohexanone in combination with the extractant tributylphosphate (TBP) (30 % vol) and a second extractant, CyMe4-BTBP (10 mM). However, there are some issues when using cyclohexanone as diluent. In this work an alternative diluent has therefore been tried in order to determine if it can replace cyclohexanone. The diluent used was hexanoic acid. In a system containing 10–12 mM CyMe4-BTBP and 30 % vol TBP in hexanoic acid with the aqueous phase 4 M HNO3, the distribution ratios for americium and curium are unfortunately low (D Am = 1.1 ± 0.27, D Cm = 1.6 ± 1.81). The concentration of CyMe4-BTBP ligand, the extractant of curium and americium, could unfortunately not be increased, because of limited solubility in hexanoic acid. The distribution ratios for fission, corrosion and activation products were low for most metals; however, cadmium, palladium and molybdenum all unfortunately have distributions ratios above 1. To conclude, low americium and curium extractions indicate that hexanoic acid is not a suitable diluent which could replace cyclohexanone in a GANEX process. 相似文献
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April R. Gillens Brian A. Powell 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):859-868
Tri-n-butyl phosphate (TBP) is the key complexant within the plutonium and uranium reduction extraction process used to extract uranium and plutonium from used nuclear fuel. During reprocessing TBP degrades to dibutyl phosphate (DBP), butyl acid phosphate (MBP), butanol, and phosphoric acid over time. A method for rapidly monitoring TBP degradation is needed for the support of nuclear forensics. Therefore, a Fourier transform infrared spectrometry-attenuated total reflectance (FTIR-ATR) technique was developed to determine approximate peak intensity ratios of TBP and its degradation products. The technique was developed by combining variable concentrations of TBP, DBP, and MBP to simulate TBP degradation. This method is achieved by analyzing selected peak positions and peak intensity ratios of TBP and DBP at different stages of degradation. The developed technique was tested on TBP samples degraded with nitric acid. In mock degradation samples, the 1,235 cm?1 peak position shifts to 1,220 cm?1 as the concentration of TBP decreases and DBP increases. Peak intensity ratios of TBP positions at 1,279 and 1,020 cm?1 relative to DBP positions at 909 and 1,003 cm?1 demonstrate an increasing trend as the concentration of DBP increases. The same peak intensity ratios were used to analyze DBP relative to MBP whereas a decreasing trend is seen with increasing DBP concentrations. The technique developed from this study may be used as a tool to determine TBP degradation in nuclear reprocessing via a rapid FTIR-ATR measurement without gas chromatography analysis. 相似文献
8.
Tri-iso-amyl phosphate (TAP): An alternative extractant to tri-butyl phosphate (TBP) for reactor fuel reprocessing 总被引:1,自引:0,他引:1
Tri-iso-amyl phosphate (TAP), an indigenously prepared extractant was utilized for reactor fuel reprocessing and compared with tri-butyl phosphate (TBP) and tri-n-hexyl phosphate (THP). The potential of these extractants was found to be in the order TAP>THP>TBP by calculating the acid uptake value (K
H). The effect of various parameters such as solvent degradation due to acid hydrolysis, radiation effect, decontamination factor and phase separation were investigated and it was found that TAP was always a better extractant in comparison to THP and TBP. In addition to this, the extraction of fission product contaminants such as 144Ce, 137Cs, 106Ru, 95Zr was almost negligible, even at very high nitric acid concentrations in the aqueous phase, indicating the potential application of TAP in actinide partitioning. Sodium carbonate solution or acidified distilled water was a good strippant for U(VI), similarly, uranium(IV) nitrate stripped Pu(IV) from the organic phase. 相似文献
9.
《中国化学快报》2022,33(11):4766-4770
In this work, the removal of 2,4,6-tribromophenol (TBP) by ferric ion-activated sulfite [Fe(III)/S(IV)] process was systematically investigated with determining the intermediate products and evaluating the influences of some operational conditions and water matrices. Our results show that batching addition of S(IV) benefits the S(IV) utilization efficiency and TBP removal, with SO4?? being the primary reactive radical accounting for TBA degradation. The maximum TBP removal in the Fe(III)/S(IV) process was observed at pH 4.0 and oxygen is essential in this process. With increasing Fe(III) and S(IV) dosages from 0.05 and 0.1 mmol/L to 0.2 and 2.0 mmol/L, respectively, TBP removal followed trends of first increase then decrease. As the acute toxicity of the TBP solution was significantly reduced, the Fe(III)/S(IV) process was believed to be a good choice in the treatment of TBP. 相似文献
10.
4,4''''-癸二酰-双-(1-苯基-3-甲基-5-吡唑啉酮)和中性磷萃取剂对铀(Ⅵ)的协同萃取 总被引:1,自引:0,他引:1
或许是考虑到溶解度的原因,迄今应用4,4′-癸二酰-双-(1-苯基-3-甲基-5-吡唑啉酮)(简称为DBPMP或H_2A)所进行的萃取研究,都是采用氯仿作为稀释剂。然而,氯仿属于A型受电子溶剂,能和具有给电子原子氧的DBPMP及中性磷萃取剂TBP或TOPO生成分子间氢键而缔合,从而降低萃取的分配比。若改用N型惰性溶剂作为稀 相似文献
11.
本文采用黄原酯棉(CCX)富集分离汞,拟定了金试剂-磷酸三丁酯(TBP)液珠萃取比色测定地质样品中微量汞的新方法,检测范围为0.05 ̄5μg/g。该法灵敏度高,选择性好,经样品验证,符合野外快速分析要求。 相似文献
12.
Alaaeldine Sh. Saleh Jong-Il Yun 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(1):93-99
Solvent extraction studies on the purification of uranium from zirconium rich sodium diuranate (SDU) feed was carried out using n-tri butyl phosphate (TBP) as extractant and n-decanol as phase modifier. The presence of Zr in SDU leached solution leads to the formation of third phase during liquid–liquid extraction of uranium which was successfully prevented by addition of n-decanol in 30% (v/v) TBP/n-dodecane mixture. A seven stage counter current extraction of SDU feed solution followed by five stage stripping were carried out using optimum concentration of phase modifier 15% n-decanol-30% TBP in n-dodecane as solvent. Based on the findings a process flow-sheet has been developed for the purification of SDU to nuclear grade ammonium diuranate. 相似文献
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Emma Aneheim Christian Ekberg Alexander Littley Elin Löfström-Engdahl Gunnar Skarnemark 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):743-748
A newly developed method for advanced reprocessing of used nuclear fuel is the Group ActiNide EXtraction (GANEX) process. It is a liquid–liquid extraction process that aims at extracting all the actinides as a group from dissolved used nuclear fuel. This extraction can either be performed after a removal of the bulk uranium or directly on the dissolution liquor. At Chalmers University of Technology in Sweden a solvent that utilizes tributyl-phosphate (TBP) and a molecule from the bis-triazine bipyridine (BTBP) class of ligands dissolved in cyclohexanone has been developed for the use in a GANEX process. Previously the system has not been tested with the presence of technetium that is one of the major fission products. Technetium is often considered a problem within reprocessing since it has a chemical behaviour that differs from most other elements in the spent fuel. Therefore, a special emphasis was put on the investigation of technetium in the selected GANEX system. It was shown that technetium is readily extracted by the GANEX solvent and that cyclohexanone is the main extractant when no other metals were present in the system. It was also found that the presence of uranium decreased the overall technetium extraction despite a slight co-extraction with TBP, while irradiation of the GANEX solvent to large doses (>1 MGy) increased its technetium extraction capability. It was also discovered that an increased nitrate concentration in the aqueous phase and an addition of other fission products both inhibited the technetium extraction even though fission product loading most likely changed the extraction mechanism to co-extraction by BTBP. 相似文献
14.
The partition of Th(IV) from H2SO4 solutions with extractant mixtures of long-chain primary amine (Primene JMT, PrJT) and tributyl phosphate (TBP) is described. Exraction was optimized at PrJT/TBP molar ratio of about 3. The dependence of extraction on acidity, salting agent, extractant concentration, diluent type and temperature, was investigated. From the results obtained, the extracted species are suggested and enthalpy data determined. 相似文献
15.
A method for the preconcentration of gold in natural waters at the sampling site using tributyl phosphate as a solid extractant [Se(TBP)] was developed as a preliminary step prior to the determination of gold by neutron activation and γ-spectrometry. The SE(TBP) was saturated with gaseous chlorine for extracting all gold species. In batch experiments gold was quantitatively retained on the SE(TBP) in 10 min. After extraction and washing, the SE(TBP) was ashed or back-extracted. Gold was quantitatively eluted with hot, neutral 0.025 M thiourea. The gold content of residues of ashing or eluents after evaporation was determined by neutron activation and γ-spectrometry. The detection limit for the overall procedure was 0.2 ng 1?1. The efficiency was tested on ‘equilibrated’ solutions prepared from river water and tracer solutions of gold. For comparison, the gold content of natural water samples was determined using preconcentration on activated charcoal. 相似文献
16.
Le Thi Kim Dung Tomoki Imai Osamu Tomioka Mikio Nakashima Kuniaki Takahashi Yoshihiro Meguro 《Analytical sciences》2006,22(11):1425-1430
The supercritical fluid extraction (SFE) method using CO(2) as a medium with an extractant of HNO(3)-tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO(2). It was thus demonstrated that the SFE method using CO(2) is useful as a pretreatment method for the analysis of uranium in ores. 相似文献
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A study of changes in the yields of radiolytic products in two-phase systems with tributyl phosphate
With the aim of studying the effects of volume ratios and composition of the organic phase on the total yields of the main degradation products of tributyl phosphate (TBP) radiolysis, the following two-phase systems were used: water-TBP-carbon tetrachloride and water-TBP-n-alkane with various ratio of TBP in the organic phase and various volume ratios of organic-aqueous phases. We examined the influence of the distribution of two-phase systems components-precursors of radiolytic products on the total yields of the main radiolytic products and mechanism involved. 相似文献
18.
With the gradual depletion of traditional zinc resources, the full use of various non-traditional zinc-containing resources has received intensive attention. However, the efficient recovery of zinc ions with low concentrations remains challenging. Here efficient and continuous recovery of zinc ions in ammoniacal chloride media by a flat supported liquid membrane system is achieved, using Cyanex923 and TBP mixed extractant as the membrane phase. This article discusses the synergistic effect between Aliquat336, Cyanex923 and TBP, the effects of feed pH, total ammonia concentration, Cl− concentration and temperature on Zn(II) transport. 相似文献
19.
Maji S Viswanathan KS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(4):972-976
The fluorescence of Tb(3+) is sensitized by complexation with dibutylphosphate (DBP) and tri-n-butylphosphate (TBP). The excitation maximum for the Tb(3+)-DBP complex occurs at 218.5 nm, while that for the Tb(3+)-TBP complex is observed at 228.0 nm. Both complexes yield Tb(3+) fluorescence at 548 nm. The difference in the excitation maxima for the two complexes has been used to advantage for the estimation of DBP in the presence of TBP. DBP is the main degradation product of TBP in the PUREX process and the method described in this work can thus serve as a useful analytical tool in monitoring the quality of the TBP in the process. This method has been shown to be applicable for the estimation of DBP when present to an extent of 0.1-10% of TBP, in TBP/dodecane solutions. 相似文献
20.
Solvent extraction is hoary yet modern technique with great scope of research due to the various intriguing phenomena in the system. Tri-n-butyl phosphate (TBP) is a well known extractant which has been extensively used for separation of uranium matrix prior to elemental profiling. In this paper, one of the impurities namely Fe is being considered as it posed a challenge to the separation due to its co-extraction with TBP along with uranium. In these studies, for the first time, the existence of cation-cation inner sphere complexes between the UO22+and Fe3+ ions in both aqueous and organic phases have been establisted in addition to the selective separation of iron from uranium sample matrix using only TBP. The data from both spectrophotometric and thermophysical studies corroborated one another confirming the presence of cation-cation interactions (CCIs). The developed solvent extraction with only TBP showed almost no interferences on the iron extraction from matrix uranium and other co-ions like aluminum and copper. This has been the first time application of pure TBP for selective removal of iron from uranium samples. The procedure possessed excellent reproducibility and robustness. 相似文献