Modeling of the Activities of Uranyl Nitrate and Nitric Acid in Mixed Solutions

Ochkin, A. V.; Меркушкин, А. О.; Nekhaevskii, S. Yu.; Gladilov, D. Yu.

doi:10.1134/s1066362218050107

Cited by 5 publications

(5 citation statements)

References 14 publications

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“…It was shown earlier [8][9][10] that the calculation using Zdanovskiy's rule and Mikulin·s equations resulted in good agreement between experimental values and calculated ones. Now the equation ( 10) and (11) have been used to calculate molal activity coefficients of nitric acid and uranyl nitrate in mixed solutions in order to increase upper limit of molal concentrations of uranyl nitrate to 2.0 mole/kg.…”

Section: Discussionmentioning

confidence: 77%

“…The densities of mixed solutions were given in [5]. This data have been transferred in the equation [10] d = 0.99704 + 0.31664c U + 0.03377c a -0.0004 c a 2.07 (2) where 0,99704 is a density of water at 25°C, c U and c a are molar concentrations of uranyl nitrate and nitric acid, d is a density of mixed solution, g/cm 3 .…”

Section: Methodology and Discussionmentioning

confidence: 99%

“…In paper [10] a calculation of activity coefficients of nitric acid and nitrate uranyl for 4 concentrations of the salt can be found. The calculation was performed using Zdanovskiy's rule [16]:…”

Section: Methodology and Discussionmentioning

confidence: 99%

“…It means that the second method should be preferred. Therefore this procedure has been considered in details in [10].…”

Section: Introductionmentioning

confidence: 99%

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Activity Coefficients of Nitrate Uranyl and Nitric Acid in Mixed Solutions

Ochkin¹,

Меркушкин²,

Gladilov³

2022

AJAC

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Aqueous solutions are frequently used in chemical technology. So numerous reference books contain basic data on major properties of binary electrolyte solutions. Usually they include densities, molar or molal concentrations, activity coefficients, water activities and sometimes osmotic coefficients. Unfortunately, most solutions are mixed ones. Therefore, it is necessary to use data of binary solutions in order to calculate thermodynamic properties of mixed solutions. For example, the aqueous phase in extraction reprocessing of nuclear reactor fuel can be considered as mixed solution of nitric acid and uranyl nitrate in first approximation. Thus, in order to calculate equilibrium during extraction of uranium with TBP it is necessary to create calculations algorithm of activity coefficients of uranyl nitrate and nitric acid with different ratios of their concentrations. Usually the integration of Gibbs-Duhem equation with some conditions is used. The first ones to offer this approach were Mc Kay and Perring in 1953. Practical implementation shows that it is recommended to integrate the equation under isopiestic conditions, meaning under constant osmotic coefficients. Zdanoskiy's rule states, that the sum of ratios of molal concentrations in mixed solution to molal concentrations in binary solutions is equal to 1. Mikulin's equations for the systems that abide by Zdanovskiy's rule allow calculations of molal coefficients of activity for such systems. Molal activity coefficients of nitrate uranyl (0.1-2.0 mole/kg) and nitric acid (0-5.0 mole/kg) in mixed solutions have been calculated using Zdanovskiy's rule and Mikulin·s equations. Analytical equations were found in order to calculate these values under different concentrations. Literature data of activity coefficients for binary solutions can be combined with calculation results from equations.

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Section: Discussionmentioning

confidence: 77%

Section: Methodology and Discussionmentioning

confidence: 99%

Section: Methodology and Discussionmentioning

confidence: 99%

“…It means that the second method should be preferred. Therefore this procedure has been considered in details in [10].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Activity Coefficients of Nitrate Uranyl and Nitric Acid in Mixed Solutions

Ochkin¹,

Меркушкин²,

Gladilov³

2022

AJAC

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show abstract

“…The activity of water in the electrolyte solution can be calculated by where M w is the molecular weight of H 2 O and ϕ is the osmotic coefficient of the solution, which can be calculated using Pitzer’s equation Densities of mixed solutions d aq are necessary to calculate molality, and the solution density d aq (g/cm 3 ) was determined using the equation …”

Section: Mathematical Modelingmentioning

confidence: 99%

Modeling of the Competition between Uranyl Nitrate and Nitric Acid upon Extraction with Tri-n-butyl Phosphate

Tan

Chang

et al. 2020

ACS Omega

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Uranium is a strategic element and plays an important role in energy resources. A H 2 O−HNO 3 − UO 2 (NO 3 ) 2 −TBP (tri-n-butyl phosphate)−diluent system is commonly used for uranium separation and purification in liquid−liquid extraction. Uranyl nitrate is promoted by the existence of nitrate at low HNO 3 concentrations but is inhibited at high HNO 3 concentrations. Considering the competitive extraction between HNO 3 and UO 2 (NO 3 ) 2 , a generic extraction model is developed. The activities of components in the aqueous phase were estimated using Pitzer models. The thermodynamic equilibrium constants and Pitzer parameters were regressed by experimental data. The resulting model was able to successfully predict uranyl nitrate, nitric acid, and water extraction over a large range of conditions (U, 0−1.8 mol/L; HNO 3 , 0−10 mol/L; TBP, 5−100 vol %) within average absolute relative deviations of 11.2, 15.7, and 23.8%, respectively. The predicted results show that water and nitric acid were extracted as di-solvates HNO 3 •(TBP) 2 •H 2 O and (TBP) 2 •2H 2 O at low nitric acid concentrations, with the formation of mono-solvates HNO 3 •TBP and HNO 3 •TBP•H 2 O as the acid concentration increased. Uranyl nitrate was shown to be rejected from the organic phase as the formation of HNO 3 •TBP and HNO 3 •TBP•H 2 O in acid was extracted at high acid concentrations.

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Estimation of Densities of Aqueous Actinide Solutions Ranging from Pure Water to Hydrated Crystals

Kumar

2024

Nuclear Technology

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Modeling of the Activities of Uranyl Nitrate and Nitric Acid in Mixed Solutions

Cited by 5 publications

References 14 publications

Activity Coefficients of Nitrate Uranyl and Nitric Acid in Mixed Solutions

Activity Coefficients of Nitrate Uranyl and Nitric Acid in Mixed Solutions

Modeling of the Competition between Uranyl Nitrate and Nitric Acid upon Extraction with Tri-n-butyl Phosphate

Estimation of Densities of Aqueous Actinide Solutions Ranging from Pure Water to Hydrated Crystals

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