共查询到20条相似文献,搜索用时 46 毫秒
1.
A. Kadous M. A. Didi D. Villemin 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(1):157-165
This work concerns the extraction of U(VI) using supported liquid membrane (SLM) by di-(2-ethylhexyl) phosphoric acid (D2EHPA)
and tri-n-octyl phosphine oxide (TOPO) with polyvinylidene difluoride (PVDF) as a membrane support. The influence of ionic
strength (S), stirring rate (V) and extraction time (t) were studied. The effect of membrane thickness on the permeability and extraction yield of uranium was investigated. A comparative
study was carried out using a 23 full factorial design between SLMs with one membrane and two membranes, and to achieve the best conditions of recovery procedure,
obtaining the mutual interaction among variables and optimizing these variables. The recovery of U(VI) is almost quantitative,
and the supported liquid membrane with two membranes in series is effective. 相似文献
2.
The solvent extraction behavior of thorium traces from the hydrochloric acid media with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) is described using 234Th as a tracer. The influence of certain variables such as extractant concentration, acidity, equilibrium time as well as UO2
2+ ions on the extraction of thorium has been investigated systematically. The back-extraction behavior of thorium from the organic phase has also been tested. The results reveal that the percent extraction of 234Th decreases with increasing hydrochloric acid concentration and thorium is easily back-extracted with an 4-6 mol/l aqueous HCl solution. At the same time, the effect of thorium extraction with PMBP was tested employing radioisotopes as multi-tracers in the irradiation of natural uranium with 14-15 MeV neutrons. The results show that thorium can be completely separated from a large amount of uranium and most of the other main reaction products. 相似文献
3.
Li Lin Yang Yan-Zhao Zeng Shan Zhu Tao Sun Si-Xiu 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(2):355-359
Summary The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP)
and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid,
sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change
for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol
and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar
ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO2(NO3)2 . BDSO . TBP. 相似文献
4.
The extraction of uranium(VI) with bis(hexylsulfinyl)methane (BHxSM) from nitric acid aqueous solution has been investigated. It was found that the extraction increased with increasing nitric acid concentration up 8.5 mol/l and then decreased. Extraction distribution ratio also increased with the bis(hexylsulfinyl)methane concentration. The extraction species appear to be UO2(NO3)2
.2BHxSM. The influences of temperature, salting-out concentration and oxalate concentration on the extraction equilibrium were also investigated, and the enthalpy of the extraction reaction was obtained. The result shows that the reaction of uranium(VI) extraction with BHxSM is an exothermic one. 相似文献
5.
Qi Chen Baole Li Junli Wang Haowei Zhu Xiwen Chen Yifu Hu Jia Zhou Xiang Li Weifang Zheng Taihong Yan 《Molecules (Basel, Switzerland)》2022,27(17)
The use of tetra-alkylcarbamides as novel ligands: N,N-butyl-N’,N’-hexylurea (L1: ABHU), and N,N-butyl-N’,N’-pentylurea (L2: ABPU), for the solvent extraction and complexation behaviors of uranium(VI) was synthesized and investigated in this study. The effects of HNO3 and NO3− concentrations in the aqueous phase on the distribution ratio of U(VI) were examined. Under 5 mol/L HNO3 concentration, DU reached 5.02 and 4.94 respectively without third-phase formation. During the extraction, slope measurements and IR spectral analysis revealed that the U(VI) complexes are a form of UO2(NO3)2·2L for both ligands. In addition, thermodynamic studies showed that the uranium extraction reaction was a spontaneous exothermic reaction. The deep structural analysis of the complexes was realized with DFT calculation. The bond length, bond properties, and topology of the complexes were discussed in detail to analyze the extraction behavior. This study enriches the coordination chemistry of U(VI) by tetra-alkylcarbamides, which may offer new clues for the design and synthesis of novel ligands for the separation, enrichment, and recovery of uranium in the nuclear fuel cycle. 相似文献
6.
The thermodynamic extraction of uranium(VI) with hexyloctylsulfoxide (HxOSO) has been studied. It was found that the distribution ratio increases with increasing nitric acid concentration up to 2.3 mol/l and then decreases. The distribution ratio also increases with increasing extractant concentration. The extracted species appears to be UO2(NO3)2
.2HxOSO. The influences of temperature, sodium nitrate and oxalate concentrations on the extraction were also investigated, and the thermodynamic functions of the extraction reaction were obtained. 相似文献
7.
Yang Yan-Zhao Sun Si-Xiu Feng Sheng-Yu 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(3):503-506
The liquid-liquid extraction behavior of 2-ethylhexyltolylsulfoxide (EHTSO) towards uranium(VI) contained in nitric acid aqueous solution has been investigated. It was found that the extraction increases with increasing nitric acid concentration up to 5.0 mol/l and then decreases. Extraction also increases with increasing extractant concentration. The extracted species appears to be UO2(NO3)2
.2EHTSO. The influences of temperature, NH4NO3 and Na2C2O4 concentrations on the extraction equilibrium were also investigated and the thermodynamic functions of the extraction reaction were obtained. 相似文献
8.
A. Senol 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(2):361-372
Liquid-liquid extraction of uranium(VI) (UO2
2+) from aqueous acidic (HCl and HNO3) solutions into a co-existing organic phase containing Alamine 308 (triisooctyl amine), TBP (tri-n-butyl phosphate) or CYANEX 302 (bis(2,4,4-trimethylpentyl) monothiophosphinic acid) and diluent (toluene) was studied at isothermal conditions (298.2 K) at aqueous phase acidity varying in the range 0.5-6 mol/dm3. All solvent systems exhibit a maximum distribution ratio restricted in the acidity range 3-4 mol/dm3. An obvious difference in extraction behavior through amine system has been observed for two acids, HCl and HNO3, distinguishing the divergent interactions attributed to the different mechanism of complexation depending on the acidic medium. The high degree of separation of UO2
2+ from HNO3 solution is feasible through a complex formation with extractants ranging in the order CYANEX 302 > TBP > Alamine 308. The results were correlated using various versions of the mass action law, i.e., a chemodel approach and a modified version of the Langmuir equilibrium model comprising the formation of one or at least two U(VI)-extractant aggregated structures. 相似文献
9.
K. A. Venkatesan K. V. Shyamala M. P. Antony T. G. Srinivasan P. R. Vasudeva Rao 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(3):563-570
Batch and dynamic extractions of uranium(VI) in 10−3–10−2M concentrations in 3–4M nitric acid medium have been investigated using a commercially available phosphinic acid resin (Tulsion
CH-96). The extraction of uranium(VI) has been studied as a function of time, batch factor (V/m), concentrations of nitric acid and uranium(VI) ion. Dual extraction mechanism unique to phosphinic acid resin has been established
for the extraction of uranium(VI). Distribution coefficient (K
d
) of uranium(VI) initially decreases with increasing concentration of nitric acid, reaches a minimum value at 1.3M, followed
by increases in K
d
. A maximum K
d
value of ∼2000 ml/g was obtained at 5.0M nitric acid. Batch extraction data has been fitted into the linearized Langmuir
adsorption isotherm. The performance of the resin under dynamic extraction conditions was assessed by following the breakthrough
behavior of the system. Effect of flow rate, concentrations of nitric acid and uranium ion in the feed on the breakthrough
behavior of the system was studied and the data was fitted using Thomas model. 相似文献
10.
Effects of operating variables on the extraction of uranium from phosphoric acid by factorial design
Extraction of uranium from aqueous phosphoric acid by DEHPA/TOPO is carried out commercially and in pilot plants. The operating variables followed are temperature, concentration of phosphoric acid, and the ratio of DEHPA/TOPO. This study investigates the influence of these operating variables by the statistical method of 23 Factorial Design on extraction of uranium from phosphoric acid. The mathematical model suggested (K=242.31–7.34C–4.784T+0.164C.T) predicts the effect of variables on the distribution ratio (extraction coefficient). The model is tested by a significance test and represented graphically. 相似文献
11.
A series of solid-phase uranium extractants were prepared by post-synthesis impregnation of a mesoporous silica support previously functionalized with octyl chains by direct silanization. Five materials were synthesized with 0, 0.2, 0.3, 0.4 and 0.5 mmol of the amidophosphonate ligand DEHCEBP per gram of functionalized solid, and the effect of the ligand concentration on the uranium extraction efficiency and selectivity of the materials was investigated. Nitrogen adsorption–desorption data show that with increasing ligand loadings, the specific surface area and average pore volume decrease as the amidophosphonate ligand fills first the micropores and then the mesopores of the support. Acidic uranium solutions with a high sulfate content were used to replicate the conditions in ore treatment leaching solutions. Considering the extraction kinetics, the equilibration time was found to increase with the ligand concentration, which can be explained by the clogging of micropores and the multilayer arrangement of the DEHCEBP molecules in the materials with their highest ligand contents. The fact that the equilibrium ligand/uranium ratio is about 2 mol/mol regardless of the ligand concentration in the material suggests that all the ligand molecules remain accessible for extraction. The maximum uranium extraction capacities ranged from 30 mg∙g−1 at 0.2 mmol∙g−1 DEHCEBP to 54 mg∙g−1 in the material with 0.5 mmol∙g−1 DEHCEBP. These materials could therefore potentially be used as solid-phase uranium extractants in acidic solutions with high sulfate concentrations. 相似文献
12.
Prof. Yanyong Wang Dr. Yanjing Wang Dr. Minglei Song Dr. Siping Chen Dr. Jianrong Wei Dr. Jie You Dr. Bo Zhou Prof. Shuangyin Wang 《Angewandte Chemie (International ed. in English)》2023,62(21):e202217601
Nano-reduced iron (NRI) is a promising uranium adsorbent due to its strong reducibility and good selectivity, but it still faces the challenges of slow kinetics, limited and non-renewable active sites. In this work, we realized high efficiency uranium extraction under ultra-low cell voltage (−0.1 V) in seawater with 20 ppm UO2(NO3)2 solution by coupling electrochemical mediated FeII/FeIII redox and uranium extraction. The adsorption capacity and extraction efficiency of NRI after electrochemical uranium extraction (EUE) could reach 452 mg/g and 99.1 %, respectively. Combined with quasi-operando/operando characterization technologies, we clarified the mechanism of EUE and revealed that continuously regenerating FeII active sites by electroreduction could significantly enhance the property of EUE. This work here provides a new electrochemical mediated and low energy consumption uranium extraction strategy which also provides a reference for other metal resource recovery. 相似文献
13.
Yang Yan-Zhao Yang Yong-Hui Xong Jun Sun Si-Xiu Bao Bo-Rong 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(1):235-238
The liquid-liquid extraction behavior of uranium(VI) from aqueous nitric acid with bis(octylsulfinyl)ethane (BOSE) in 1,1,2,2-tetrachloroethane
has been studied over a wide range of conditions. The extracted species appears to be UO2(NO3)2·2BOSE. It was found that the extraction increases with increasing nitric acid concentration up to 7 mol/l and then decreased.
Extraction also increases with increasing extractant concentration. The influence of temperature and salting-out agent concentration
on the extraction equilibrium and stripping of uranium(VI) was also investigated and the enthalpy of the extraction reaction
was obtained. 相似文献
14.
Guan-Quan Wang Ji Zhang Shun-Zhong Luo Na Wang Hong-Yuan Wei Wen-Jin Wang Yu-Qing Yang Guo-Ping Liu Xiao-Qi Yu 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(2):365-369
The recovery of uranium(VI) from chloride solution using a liquid emulsion membrane (LEM) technique was studied. The emulsion
is constituted by the quaternary salt of benzyloctadecyldimethyl ammonium chloride (BODMAC, R4NCl) as a carrier, kerosene as organic diluent, Span 80 as emulsifying agent and 0.5 mol/l Na2CO3 as stripping phase. The important variables affecting the LEM permeation process such as the concentrations of extractant,
internal strip phase, types of organic diluent, and the presence of magnesium chloride or magnesium sulfate were investigated.
It was found that, at a given condition, the maximum extraction rate of uranium(VI) reached 80%. The emulsion was stable at
low pH in the presence of certain amounts of electrolytes such as NaCl and MgCl2. 相似文献
15.
Yin Dongguang Liang Yufu Miao Zengsheng Li Baolong Bai Chunqi Luo Zhifu 《Journal of Radioanalytical and Nuclear Chemistry》2002,254(3):629-631
The separation of gram quantities of uranium from fission products has been investigated by extraction chromatography. The separation which is based on the difference in distribution coefficients between uranium and the fission products on a tributyl phosphate (TBP) resin in nitric acid medium, was carried out by means of high acidity feed and stepwise elution on a TBP chromatography column. The results show that this technique is capable to separate 5 g of uranium from a large quantity of fission products. The recovery of uranium is more than 99%. The decontamination factors of g- and b-activities were 2.1.103 and 2.3.103, respectively. 相似文献
16.
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
17.
Jia Wei-Jie Zhou Zu-Min He A-Di Wang Zhi-Lin Chin Chi-Tsung 《Journal of Radioanalytical and Nuclear Chemistry》1989,130(1):187-194
Laser-induced optical fiber fluorimetry has been first used to analyze uranium(VI) concentration in the kinetic studies on the extraction of uranium(VI) between 0.5 mol/l H3PO4 solution and HDEHP-cyclohexane system with a Lewis cell. The effects of stirring speed, temperature and concentrations of uranium(VI) and HDEHP on the rate of extraction were examined. These data show that the extraction rate of uranium(VI) in this system is controlled by the chemical reaction at the interface. The rate equations and the rate constants of forward and reverse extraction are obtained. The mechanism of the extraction is discussed. 相似文献
18.
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 HNO3 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
19.
A voltammetric method is reported for the determination of low uranium concentrations in natural waters. A very strongly adsorbed mixed complex of uranyl ion with 2-thenoyltrifluoroacetone and tri-n-butyl phosphate is applied. Synergic adsorption is obtained compared with the adsorption obtained with either ligand alone. In 0.55 mol dm?3 sodium chloride, the detection limit was 10?10 mol dm?3 uranyl ion after accumulation for 10 min at ?0.1 V vs. Ag/AgCl. For the natural level of uranium in sea water (about 10?8 mol dm?3), accumulation for 2 min was sufficient. 相似文献
20.
Liu Mouwu Wang Yanfei Ma Zhili Luo Yige 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(1):279-288
Poly(cyclotriphosphazene-co-phloroglucinol) (PCPP) microspheres, a new solid phase extraction for extracting uranium(VI), synthesized via one-pot precipitation copolymerization. The PCPP microspheres were characterized by FT-IR, SEM/EDS, zeta potential and N2 adsorption/desorption isotherms. Through the extraction experiment to evaluate the extraction behavior of the PCPP microspheres for uranium(VI). The extractant can achieve the optimal effect under the conditions of contact time with 60 min, pH = 3.5, initial concentration 100 mg L−1 and extractant dosage 0.70 g L−1. The extraction behavior obeyed with the pseudo second-order model and Langmuir isotherm model.
相似文献