scholarly journals Uranyl oxalate species in high ionic strength environments: stability constants for aqueous and solid uranyl oxalate complexes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yongliang Xiong ◽  
Yifeng Wang
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Nuclear Waste ◽  
Waste Disposal ◽  
Infinite Dilution ◽  
Uranyl Ion ◽  
Natural Environments ◽  
Wide Range ◽  
Oxalate Complexes ◽  
Uranyl Oxalate

Abstract Uranyl ion, UO2 2+, and its aqueous complexes with organic and inorganic ligands can be the dominant species for uranium transport on the Earth surface or in a nuclear waste disposal system if an oxidizing condition is present. As an important biodegradation product, oxalate, C2O4 2−, is ubiquitous in natural environments and is known for its ability to complex with the uranyl ion. Oxalate can also form solid phases with uranyl ion in certain environments thus limiting uranium migration. Therefore, the determination of stability constants for aqueous and solid uranyl oxalate complexes is important not only to the understanding of uranium mobility in natural environments, but also to the performance assessment of nuclear waste disposal. Here we developed a thermodynamic model for the UO2 2+–Na+–H+–Cl––ClO4 ––C2O4 2––NO3 ––H2O system to ionic strength up to ∼11 mol•kg−1. We constrained the stability constants for UO2C2O4(aq) and UO2(C2O4)2 2− at infinite dilution based on our evaluation of the literature data over a wide range of ionic strengths up to ∼11 mol•kg−1. We also obtained the solubility constants at infinite dilution for solid uranyl oxalates, UO2C2O4•3H2O, based on the solubility data over a wide range of ionic strengths. The developed model will enable for the accurate stability assessment of oxalate complexes affecting uranium mobility under a wide range of conditions including those in deep geological repositories.

The Effect Of W/C Ratio And Cement Type On The Longevity Of Grouts For Use In A Nuclear Fuel Waste Disposal Vault

1988 ◽  
Vol 137 ◽  
Author(s):  
Maria Onofrei ◽  
Malcolm Gray
Keyword(s):  
Ionic Strength ◽  
Nuclear Fuel ◽  
Waste Disposal ◽  
Exchange Capacity ◽  
Fractional Factorial ◽  
Effect Of Temperature ◽  
Cement Type ◽  
Slag Cement ◽  
Wide Range ◽  
Nuclear Fuel Waste

AbstractCement-based grouts are being considered for use as sealing materials in the Canadian concept for nuclear fuel waste disposal. This paper describes laboratory studies of the longevity of these materials, with special emphasis on the effect of hardened grout porosity and cement type. The longevity properties determined for reference grout (90% Type 50 cement, 10% silica fume and superplasticizer) are compared with those of a slag cement grout.The fractional factorial statistical method of Box-Behnken was used to design a series of leach tests, which covered a wide range of conditions that could occur in a nuclear waste disposal vault. The leach tests have been carried out to determine the effect of temperature, ionic strength of groundwater, and cation exchange capacity (CEC) of clay (which may be in contact with the grout) on the leach resistance of the cement. The temperature ranged from 25 to 150°C and the ionic strength of the groundwaters from 0.0015 to 1.37 mol. Leach rates of Ca and Si were taken as the major indicators of the long-term chemical stability of the grouts.Preliminary analysis suggests that the reference grout would be more stable than slag cement in the high-temperature environment of a nuclear fuel waste disposal vault. Within the ranges investigated, decreasing the porosity appears not to significantly decrease leach rates.

A tool to draw chemical equilibrium diagrams using SIT: Applications to geochemical systems and radionuclide solubility

2014 ◽  
Vol 1665 ◽  
pp. 111-116 ◽  
Author(s):  
I. Puigdomènech ◽  
E. Colàs ◽  
M. Grivé ◽  
I. Campos ◽  
D. García
Keyword(s):  
Experimental Data ◽  
Ionic Strength ◽  
Undergraduate Students ◽  
Nuclear Waste ◽  
Chemical Equilibrium ◽  
Equilibrium Constants ◽  
Nuclear Waste Repository ◽  
Wide Range ◽  
Java Programs ◽  
Institute Of Technology

ABSTRACTA set of computer programs has been developed to draw chemical-equilibrium diagrams. This new software is the Java-language equivalent to the Medusa/Hydra software (developed some time ago in Visual basic at the Royal Institute of Technology, Stockholm, Sweden). The main program, now named “Spana” calls Java programs based on the HaltaFall algorithm. The equilibrium constants that are needed for the calculations may be retrieved from a database included in the software package (“Database” program). This new software is intended for undergraduate students as well as researchers and professionals.The “Spana” code can be easily applied to perform radionuclide speciation and solubility calculations of minerals, including solubility calculations relevant for the performance assessment of a nuclear waste repository. In order to handle ionic strength corrections in such calculations several approaches can be applied. The “Spana” code is able to perform calculations based on three models: the Davies equation; an approximation to the model by Helgeson et al. (HKF); and the Specific Ion-Interaction Theory (SIT). Default SIT-coefficients may be used, which widens the applicability of SIT significantly.A comparison is made here among the different ionic strength approaches used by “Spana” (Davies, HKF, SIT) when modelling the chemistry of radionuclides and minerals of interest under the conditions of a geological repository for nuclear waste. For this purpose, amorphous hydrous Thorium(IV) oxide (ThO2(am)), Gypsum (CaSO4·2H2O) and Portlandite (Ca(OH)2) solubility at high ionic strengths have been modelled and compared to experimental data from the literature. Results show a good fitting between the calculated values and the experimental data especially for the SIT approach in a wide range of ionic strengths (0-4 M).

Stability constants of technetium(IV) oxalate complexes as a function of ionic strength

2006 ◽  
Vol 94 (3) ◽  
Author(s):  
Yuanxian Xia ◽  
Nancy J. Hess ◽  
Andrew R. Felmy
Keyword(s):  
Ionic Strength ◽  
Solvent Extraction ◽  
Stability Constants ◽  
Extraction Method ◽  
Solvent Extraction Method ◽  
Oxalate Complexes ◽  
The Stability

SummarySolvent extraction method was used to determine the stability constants of Tc(IV) with oxalate anions in NaCl solutions ranging in concentration from 0.5 M to 2.0 M. All experiments were conducted in an atmosphere-controlled chamber under Ar atmosphere (<1.0 ppm O

scholarly journals Intracellular Ionic Strength Sensing Using NanoLuc

2021 ◽  
Vol 22 (2) ◽  
pp. 677
Author(s):  
Tausif Altamash ◽  
Wesam Ahmed ◽  
Saad Rasool ◽  
Kabir H. Biswas
Keyword(s):  
Thermal Stability ◽  
Phase Separation ◽  
Drug Discovery ◽  
Ionic Strength ◽  
Cellular Signaling ◽  
Live Cells ◽  
Protein Activity ◽  
Cellular Survival ◽  
Cellular Processes ◽  
Wide Range

Intracellular ionic strength regulates myriad cellular processes that are fundamental to cellular survival and proliferation, including protein activity, aggregation, phase separation, and cell volume. It could be altered by changes in the activity of cellular signaling pathways, such as those that impact the activity of membrane-localized ion channels or by alterations in the microenvironmental osmolarity. Therefore, there is a demand for the development of sensitive tools for real-time monitoring of intracellular ionic strength. Here, we developed a bioluminescence-based intracellular ionic strength sensing strategy using the Nano Luciferase (NanoLuc) protein that has gained tremendous utility due to its high, long-lived bioluminescence output and thermal stability. Biochemical experiments using a recombinantly purified protein showed that NanoLuc bioluminescence is dependent on the ionic strength of the reaction buffer for a wide range of ionic strength conditions. Importantly, the decrease in the NanoLuc activity observed at higher ionic strengths could be reversed by decreasing the ionic strength of the reaction, thus making it suitable for sensing intracellular ionic strength alterations. Finally, we used an mNeonGreen–NanoLuc fusion protein to successfully monitor ionic strength alterations in a ratiometric manner through independent fluorescence and bioluminescence measurements in cell lysates and live cells. We envisage that the biosensing strategy developed here for detecting alterations in intracellular ionic strength will be applicable in a wide range of experiments, including high throughput cellular signaling, ion channel functional genomics, and drug discovery.

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