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Abstract  

The extraction of uranium (VI) from nitric acid by N-octanoylpyrrolidine (OPOD) in toluene has been investigated at varying concentrations of nitric acid, extractant, salting-out agent LiNO3 and at different temperatures. The mechanism of extraction is discussed in the light of the obtained results.

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Abstract  

N,N'-Dioctanoylpiperazine (DOPEZ), a novel extractant for U(VI) in carbon tetrachloride has been studied. The principal factors affecting the U(VI) distribution ratio, i.e., the concentration of aqueous nitric acid, extractant, salting-out agent and temperature, were investigated.

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Abstract  

A systematic investigation has been carried out on the extractive behavior of N,N'-dihexanoylpiperazine (DHPEZ) with respect to U(VI) in five diluents, from aqueous nitric acid media. The variation of U(VI) distribution ratio with the concentrations of aqueous nitric acid, extractant, salting-out agent and with temperature has been investigated and discussed. The increasing order of extractive ability of DHPEZ towards U(VI) is: chloroform, carbon tetrachloride, 1,4-dimethyl-benzene, toluene, benzene. The composition of the extracted species and extraction constants as well as the enthalpy changes are given.

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Abstract  

Extraction of uranium(VI), thorium(IV) from nitric acid has been studied with N-octylcaprolactam and N-(2-ethyl)hexylcaprolactam. Distribution coefficients of U(VI), Th(IV) and HNO3 as a function of aqueous NHO3 concentration, extractant concentration and temperature have been studied. The compositions of extracted species, thermodynamic parameters of extraction have been evaluated. Third phase formation in extraction of U(VI) has been studied. Back extraction behavior of U(VI) and Th(IV) from the organic phase has also been tested. The results obtained are compared with those obtained by using TBP under the same experimental conditions.

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New extractants for reprocessing of spent Th-U fuel

Extraction of U(VI) and Th(IV) from nitric acid media by Di(2-ethylhexyl)sulfoxide (DEHSO)

Journal of Radioanalytical and Nuclear Chemistry
Authors:
Bao Bo-Rong
,
Bao Ya-Zhi
,
Shen Chao-Hong
,
Wang Gao-Dong
,
Qian Jun
, and
Cao Zheng-Bai

Abstract  

A study on solvent extraction of U(VI), Th(IV) and HNO3 from nitric acid media by DEHSO is described. Extraction coefficients of U(VI), Th(IV) and HNO3 as a function of aqueous HNO3 concentration, extractant concentration and temperature have been studied. From the data the compositions of extracted species, equilibrium constants and enthalpies of extraction reaction have been evaluated. Back-extraction of U(VI) and Th(IV) from the organic phase by dilute nitric acid has also been tested. All studies on DEHSO are compared with TBP.

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Abstract  

N,N,N′,N′-tetrahexylsuccinylamide (THSA) was used for the extraction of U(VI) and Th(IV) ions from nitric acid media into n-dodecane. Extraction distribution ratios of U(VI) and Th(IV) as a function of nitric acid concentration, extractant concentration and temperature have been studied. It was found that THSA as a new extractant is superior in some aspects to TBP for extraction of U(VI) and Th(IV). The extraction of nitric acid was also investigated. At low acidity, the main adduct of THSA and HNO3 is THSA·HNO3. THSA·(HNO3)2 and THSA·(HNO3)3 also formed at high acidity. The composition of the species, equilibrium constants and enthalpies of the extraction reactions have also been calculated. The suggested formation of the 1:2:1 ratio of uranyl(VI) ion and the 1:4:2 ratio of thorium(IV) ion, nitrate ion and THSA as the extracted species was further confirmed by the IR spectra of U(VI) and Th(IV) extracts.

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Abstract  

N,N,N′,N′-tetrabutylmalonamide (TBMA) was used for extraction of uranyl(II) ion from nitric acid media into n-dodecane. The effects of nitric acid concentration, extractant concentration, temperature and back extraction on distribution coefficients of uranyl(II) ion have been studied. The extraction of nitric acid is also studied. The main adduct of TBMA and HNO3 is (TBMA)2·HNO3 in 1.0 mol/l nitric acid solution. The 1:2:2 complex of uranyl(II) ion, nitrate ion and TBMA as extracted species is further confirmed by IR spectra of the extraction of uranyl(II) ion with TBMA. The values of thermodynamic parameters have also been calculated.

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Abstract  

N,N-dialkylamides having ethyl (DEDOA), butyl (DBDOA) and octyl (DODOA) groups as the alkyl substituents were synthesized in order to investigate their selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction distribution coefficients of U(VI) with the amides in toluene decrease in the order of DODOA>DBDOA>DEDOA. The structure of the extracted species was suggested from the dependence of the distribution ratio on the concentration of the extractant, with the aid of FT-IR spectra. The structural effect on the extraction capability of U(VI) was discussed in terms of the molecular modelling. The effects of temperature on the distribution ratios were also considered, and the extraction reaction enthalpy was calculated.

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Abstract  

The influence of the concentration of nitric, hydrochloric and phosphoric acids, petroleum sulfoxides (PSO), salting-out agent, kind of diluent and temperature on the distribution ratio of U(VI) and Th(IV) has been systematically studied. It is found that the extraction regularity of PSO is similar to that of TBP. The distribution ratio in phosphoric acid is lower, but it increases with the increase of hydrochloric acid concentration and reaches a high value. The U(VI) exhibits the maximum distribution ratio at 3–4 mol/l HNO3. The distribution ratio of U(VI) and Th(IV) increases rapidly in the presence of a salting out agent. The extracted compounds are determined to be UO2(NO3)22PSO and Th(NO3)42PSO. The extraction enthalpies of U(VI) and Th(IV) with PSO were also calculated.

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Abstract  

The partition of uranium(VI) between nitric acid and N,N-dibutyldecanamide (DBDEA) in kerosene has been investigated at various concentrations of nitric acid, extractant and salting-out agent LiNO3. The mechanism of extraction is discussed in the light of the results obtained. The effect of TBP on the extraction of uranium(VI) with DBDEA has also been considered. There is an apparent synergistic effect with these two extractants at low concentration of TBP, however, one sees a decrease in extraction distribution at higher concentration. IR spectra show that there is no apparent interaction between the two kinds of extractants. The stoichiometry of the synergistic extracted species has been determined.

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