853. The spectra and stability of some neptunium complex ions in water and methanol

Gainar, I.; Sykes, Keith

doi:10.1039/jr9640004452

Cited by 19 publications

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“…[20] on the redox potential of Np(V)/Np(VI) in 4 M NaClCV NaCl mixtures provided no evidence for the formation of Np(V) chloro complexes. On the other hand, a cation exchange experiment of Gainar and Sykes [21] in 2 M HCIO4/HCI and a solvent extraction experiment of Rao et al [22] in 2 M NaC10 4 /NaCl solution clearly demonstrated that the activity of the Np0 2 ion significantly decreases, when Perchlorate ions of the bulk medium are replaced by chloride ions. In order to avoid changes in activity coefficients, ionic strength was kept constant at / = 2 mol/L in these phase equilibrium experiments, and the results were interpreted for the formation of a Np(V) chloro complex, Np0 2 Cl.…”

Section: Introductionmentioning

confidence: 93%

“…Only a few studies on the Np(V) chloride complexation have been reported [19][20][21][22] and conclusions drawn by different authors are contradictory. Hindman et al [19] observed no differences in absorption spectra of Np(V) in 1 M HCIO4 and 1 M HCl and thus ruled out complex formation in HCl solution.…”

Section: Introductionmentioning

confidence: 99%

“…In order to avoid changes in activity coefficients, ionic strength was kept constant at / = 2 mol/L in these phase equilibrium experiments, and the results were interpreted for the formation of a Np(V) chloro complex, Np0 2 Cl. The stability constant of Np0 2 Cl was calculated to be ß\ = 0.51 ±0.06 [21] and 0.38±0.04 [22], respectively. However, it is to note that the authors could not distinguish among the different effects, which might cause a decrease of the NpOJ activity: inner sphere complexation, outer sphere complexation and electrostatic ion association, i.e.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO⁺ ₂ Ion

et al. 1995

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The interaction between NpOJ and chloride ions has been investigated at 25 °C by means of absorption spectroscopy and solvent extraction with NaDNNS. The experimental results are discussed by two different approaches: (1) the Np(V) chloride complexation and (2) the strong ion-ion interaction. The formation constants of the complexes Np0 2 Cl and Νρ0 2 0 2 are determined by solvent extraction experiments at different ionic strength, I = 1.0, 2.0, 3.0 and 5.0 mol/L (NaC10"/NaCl). The complexation constants extrapolated to / = 0 are found to be very low, i.e. logyS? = -0.29±0.05 and log/g < -1. The spectroscopic study shows no evidence for the formation of strong inner sphere complexes. Therefore, the interaction between NpOJ and CI" is considered as strong ion-ion interaction without invoking Np(V) chloro complexes. Applying the Pitzer equations, the interaction parameters β°\ β" and C* for NpOJ/ClO; and NpOJ/ CI" have been evaluated from trace activity coefficients of the Np0 2 ion in 0.2-5 M NaC10 4 and 0.2-5 M NaCl, respectively. The results are applied for calculating the solubility products of Np0 2 0H(s), NaNp0 2 C0 3 (s) and Na 3 Np0 2 (C0 3 ) 2 (s) as a function of the NaC10 4 and NaCl concentration. In both media, there is excellent agreement between experimental and predicted solubility products.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO⁺ ₂ Ion

et al. 1995

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“…4. Since the chloride complexation of the pentavalent actinide ion is negligibly weak [14,27,28] in comparison with hydrolysis reactions in the pH range under investigation, the solubilities shown in Fig. 4 are assumed to be caused by hydrolysis reactions alone.…”

Section: Am(v) Hydrolysis In Saline Solutionmentioning

confidence: 99%

Hydrolysis Reactions of Am (II I) and Am(V)

Stadler¹,

Kim²

1988

Radiochimica Acta

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Hydrolysis reactions of Am (III) have been investigated in noncomplexing solution as well as saline solutions under CO,-free conditions. The solubility experiment in combination with radiometric pH-titration is carried out for the pH range from 6 to 13, at different ionic strengths. In non-complexing solution, the solubility product is found to be increasing along with an increase of the specific α-activity in a given experimental solution. In concentrated NaO solutions (I è 3M, pH > 7) with high specific inactivities ( > 1 Ci/L), the α-radiolysis starts generating substantial amounts of oxidized chlorine species, e. g. CIO", which results in the oxidation of Am (III) to Am(V). The hydrolysis reaction of Am(V) in 3 Af NaCl is also investigated by radiometric pH-titration. Solubility products (Ksp) of Am(OH) 3 (s) and AmO,(OH)(s) and hydrolysis constants of Am (III) and Am(V) are calculated from the solubility data. The speciation of different hydrolysis products, undertaken by laser-induced photoacoustic spectroscopy (LPAS), has verified probable species assessed theoretically on the basis of solubility experiments.

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“…为了获取更准确的配位常数, Rao 等 [40] 以吸收光谱- [42] , -0.55±0.09 [43] 及-0.52 等. 近年来, Topin 等 [44] 以 CE-ICP-MS 方法得到了在 I＝1.0 mol/L (0.9 mol/L NaNO 3 ＋ 0.1 mol/L NaClO 4 )条件下, SO -之间, 其与 Np(V)、Pu(V)的配位能力较强.…”

Section: Counclassified

Advances in Environmental Coordination Chemistry of Np and Pu with Inorganic Anions in Aqueous Solution

Dong¹,

Cao²,

Xu³

et al. 2021

Acta Chimica Sinica

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Neptunium (Np) and plutonium (Pu) are two important actinides in nuclear industry. They can be generated through neutron capture of uranium (U) in reactors or decay from other transuranic elements. Representative isotopes of Np and Pu such as 237 Np and 239 Pu have long half-lives and possess high radiotoxicity, therefore may impose great hazard to biological system if they are released into the environment. The rich redox chemistry of Np and Pu further adds complexity of their chemical behavior in the environment. The coordination chemistry of Np and Pu in aqueous solution is of great significance to help understand and control their speciation distribution and migration behaviors in aqua environment. This article reviews the advances in coordination chemistry of Np and Pu with several common inorganic anions (OH -,PO -) in aqueous solution, especially the speciation and coordination thermodynamics between Np/Pu in different oxidation states and these anions. In general, Np and Pu ions in the same oxidation state exhibit similar coordination behavior (species, structure, stability constants, etc.) when coordinating with the same anion. The coordination strength for Np/Pu ions in different oxidation states with the same anion ligand is roughly in the order of IV＞III, VI＞V. For the coordination of Np/Pu ions with different anions, the strength sequences are OH -＞F -＞ 2 4 H PO -＞ 3 NO -＞Cl for monovalent anions andHPO -＞ 2 4 SOfor divalent anions. Factors such as instability of Np/Pu ions in some oxidation states, weak complexation, and low solubility of the complexes in the aqueous solution cause difficulties in obtaining precise and reliable coordination parameters for these ions experimentally. Moreover, the coordination parameters determined by different methods may vary with each other. To obtain more reliable parameters for the coordination of Np/Pu ions with these anions in the future, the use of more advanced characterization methods and the assistance of theoretical computation may provide strong support.

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853. The spectra and stability of some neptunium complex ions in water and methanol

Abstract: These values may be low on account of the slit-width effect. Hindman, Mapusson, and LaChapelIe give 126 at 723 m p and 160 at 964 m p for aqueous ~M-HCI; and 92 at 723 mp and 75 at 971 m p for aqueous IM-H,SO,.

Cited by 19 publications

References 0 publications

Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO⁺ ₂ Ion

Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO⁺ ₂ Ion

Hydrolysis Reactions of Am (II I) and Am(V)

Advances in Environmental Coordination Chemistry of Np and Pu with Inorganic Anions in Aqueous Solution

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853. The spectra and stability of some neptunium complex ions in water and methanol

Abstract: These values may be low on account of the slit-width effect. Hindman, Mapusson, and LaChapelIe give 126 at 723 m p and 160 at 964 m p for aqueous ~M-HCI; and 92 at 723 mp and 75 at 971 m p for aqueous IM-H,SO,.

Cited by 19 publications

References 0 publications

Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO+ 2 Ion

Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO+ 2 Ion

Hydrolysis Reactions of Am (II I) and Am(V)

Advances in Environmental Coordination Chemistry of Np and Pu with Inorganic Anions in Aqueous Solution

Contact Info

Product

Resources

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Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO⁺ ₂ Ion

Thermodynamics of Neptunium(Y) in Concentrated Salt Solutions: Chloride Complexation and Ion Interaction (Pitzer) Parameters for the NpO⁺ ₂ Ion