A structural study on uranyl (VI) nitrate complexes with cyclic amides: N-n-butyl-2-pyrrolidone, N-cyclohexylmethyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidone

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The solubility of UO 2 (NO 3 ) 2 (NRP) 2 (NRP = N-alkyl-2-pyrrolidone) in aqueous solutions with HNO 3 (0-5.0 M) and the corresponding NRP (0-0.50 M) has been studied. As a result, the solubility of each species of UO 2 (NO 3 ) 2 (NRP) 2 generally decreases with increasing concentrations of HNO 3 and the corresponding NRP (C HNO 3 and C NRP , respectively) in the supernatant. The solubility of UO 2 (NO 3 ) 2 (NRP) 2 also depends on the type of NRP; a higher hydrophobicity of NRP generally leads to a lower solubility of UO 2 (NO 3 ) 2 (NRP) 2 . The logarithms of effective solubility products (K eff ) of

Section: Introductionmentioning

confidence: 99%

Solubility of Uranyl Nitrate Precipitates withN-Alkyl-2-pyrrolidone Derivatives (Alkyl =n-Propyl,n-Butyl,iso-Butyl, and Cyclohexyl)

Kohara

Noda

Nogami

et al. 2009

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“…The obtained crystals were filtered and washed with cold ethanol and hexane, followed by air-drying. [25][26][27][28][29]32) …”

Section: Syntheses Of Uomentioning

confidence: 99%

“…Recently, it has been reported that pyrrolidone derivatives being amide compounds can selectively precipitate U(VI) in HNO 3 solutions [25][26][27][28][29] and that N-vinylpyrrolidone resin adsorbs U(VI) selectively. 30) From these viewpoints, the pyrrolidone derivatives are expected to be promising selective extractants for U(VI).…”

Section: Introductionmentioning

confidence: 99%

Extraction of Uranium(VI) from Nitric Acid Solution Using Pyrrolidone Derivatives

Takahashi¹,

Hotokezaka²,

Noda³

et al. 2009

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The extraction behavior of uranyl species from HNO 3 aqueous solutions using CH 2 Cl 2 containing pyrrolidone derivatives as extractants has been studied to find an alternative to tributyl phosphate as an extractant. In this study, we used N-cyclohexyl-2-pyrrolidone (NCP), N-octyl-2-pyrrolidone (NOP), and N-dodecyl-2-pyrrolidone (NDP) as the extractants. As a result, it was found that NCP, NOP, and NDP (abbreviated as NRP) extract U(VI) as UO 2 (NO 3 ) 2 (NRP) 2 , that a part of NCP in CH 2 Cl 2 phase is moved to the aqueous phase, and that the extractability (corresponding distribution ratio) of U(VI) increases with increasing [HNO 3 ] int from 7% (0.08) (½HNO 3 int ¼ 0:1 M, ½NRP int ¼ 1:0 M) to more than 90% (11) (½HNO 3 int ¼ 3:0 M, ½NRP int ¼ 1:0 M). From these results, it is expected that NOP and NDP extract U(VI) effectively from HNO 3 solution of more than 3 M and that the extracted U(VI) species are stripped by using HNO 3 aqueous solution of low concentration.

“…In this experiment, U(IV) was used as a simulant of Pu(IV), because of similarity of their chemical properties [18,19]. As a result, it was found that 1,3-dimethyl-2-imidazolidone (DMI) does not have precipitation ability to U(IV) but U(VI) [20,21]. In the previous papers [11,16], we reported that NRPs with low hydrophobicity have little precipitation ability to Pu(IV) and also do not precipitate U(VI) effectively.…”

Section: Introductionmentioning

confidence: 99%

“…In the previous papers [11,16], we reported that NRPs with low hydrophobicity have little precipitation ability to Pu(IV) and also do not precipitate U(VI) effectively. In contrast, the DMI molecule has high precipitation ability to U(VI) in spite of the low hydrophobicity [20]. An understanding of selective precipitation phenomenon of DMI would lead to give hints for finding the factors to control precipitation ability to U(VI) and Pu(IV).…”

Section: Introductionmentioning

confidence: 99%

A study on selective precipitation ability of cyclic urea to U(VI) for developing reprocessing system based on precipitation method

Suzuki¹,

Kawasaki²,

Kohara³

et al. 2012

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We have proposed a new reprocessing system based on precipitation method. In order to find out precipitants with high selectivity to U(VI) and to investigate factors controlling precipitation ability to U(VI) and U(IV), properties of 3,4,5,6-tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone (DMPU) as a precipitant have been examined by using U(VI), U(IV) as a simulant of Pu(IV), and simulated fission products (FPs). We have evaluated precipitation ratios (P.R.) for U(VI) and U(IV), solubility of U(VI) precipitates to 3.0 mol dm 73 (M) HNO 3 solution, melting points (MPs) of U(VI) precipitates, log P (distribution ratio of a substance in 1-octanol/water biphasic system, a measure of hydrophobicity) of precipitants, and decontamination factors (DFs) of FPs. The properties of DMPU were compared with those in systems using N-n-butyl-2-pyrrolidone (NBP), N-cyclohexyl-2-pyrrolidone (NCP), and other pyrrolidone derivatives as the precipitant. The P.R. values of DMPU to U(VI) and U(IV) in 3. , and Sm(III)] used in the present study were found to be more than 100. Even in U(VI)-U(IV) coexisting system, the selectivity of DMPU to U(VI) was higher than those of NBP and NCP. This selective precipitation ability of DMPU to U(VI) was evaluated by the solubility of U(VI) precipitates on the basis of their MPs and the log P values of precipitants. As a result, it was found that the precipitants having low hydrophobicity and forming the U(VI) precipitates with high MPs have highly selective precipitation ability to U(VI).