Diffusion of Uranium in Compacted Sodium Bentonite

1992 ◽  
Vol 294 ◽  
Author(s):  
Arto Muurinen ◽  
Kaija Ollila ◽  
Jarmo Lehikoinen
Keyword(s):  
Uranium Oxide ◽  
Saline Water ◽  
Diffusion Mechanism ◽  
Effective Diffusion ◽  
Salt Content ◽  
Sodium Bentonite ◽  
Effective Diffusion Coefficients ◽  
Anionic Complexes ◽  
Aerobic And Anaerobic ◽  
Wyoming Bentonite

ABSTRACTIn this study the diffusion of uranium dissolved from uranium oxide fuel was studied experimentally in compacted sodium bentonite (Wyoming bentonite MX-80). The parameters varied in the study were the density of bentonite, the salt content of the solution and the redox conditions. In the studies with non-saline water of total dissolved solids about 300 ppm, uranium was both in aerobic and anaerobic experiments as anionic complexes and followed the anionic diffusion mechanism. Anion exclusion decreased effective diffusion coefficients, especially in more dense samples. In the studies with saline water of total dissolves solids about 35000 ppm, uranium appeared in the aerobic experiments probably as cationic complexes and followed the cationic diffusion mechanism. Uranium in the saline, anaerobic experiment was probably U(OH)4 and followed the diffusion mechanism of neutral species.

scholarly journals Diffusion Mechanism of Leading Technology in the New Energy Industry Based on the Bass Model

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongying Wang ◽  
Bing Sun
Keyword(s):  
Expected Utility ◽  
Simulation Analysis ◽  
Diffusion Mechanism ◽  
Effective Diffusion ◽  
Energy Industry ◽  
Bass Model ◽  
Property Development ◽  
Industrial Transformation ◽  
New Energy ◽  
The Government

With the increasing difficulties associated with heating, the new energy industry has become the mainstay for property development. The effective diffusion of leading technologies supplies a social edge for enterprise core technologies, and this is also a necessary topic for industrial transformation and optimization. Within the international context of energy conservation and emission reduction, the scientific and in-depth study of the diffusion mechanisms underlying leading technologies in the new energy industry have vital theoretical significance for the promotion of the diffusion of leading technologies. Based on the introduction of the Bass model and one extension model, this paper constructs the diffusion model of the new energy industry’s leading technology and analyzes its diffusion mechanism. The identified mechanism indicates that in the case of imperfect market and policy environments, the diffusion of the leading technology of the new energy industry is mainly influenced by the “expected utility” of innovators and the “actual utility” of imitators. The diffusion of the leading technology in innovator enterprises of the new energy industry is mainly affected by the “expected utility,” while the diffusion in imitator enterprises is affected by the “actual utility.” These influences are verified by simulation analysis. Based on the diffusion mechanism, several suggestions are presented for the promotion of the diffusion mechanism of leading technology, with the aim to provide references for the government, industry associations, and enterprises for relevant decision-making.

Laboratory assessment of semi-permeable properties of a natural sodium bentonite

2018 ◽  
Vol 55 (11) ◽  
pp. 1611-1631 ◽  
Author(s):  
Andrea Dominijanni ◽  
Nicolò Guarena ◽  
Mario Manassero
Keyword(s):  
Mechanistic Model ◽  
Effective Diffusion ◽  
Swelling Pressure ◽  
Solute Concentration ◽  
Transport Processes ◽  
Laboratory Assessment ◽  
Sodium Bentonite ◽  
Clay Particles ◽  
Chemical Osmosis ◽  
Multi Stage

The relevance of the semi-permeable properties of bentonites, which affect both their transport processes and mechanical behaviour, has been assessed through the experimental determination of three parameters: the reflection coefficient, ω; the osmotic effective diffusion coefficient, [Formula: see text]; and the swell coefficient, ϖ. Two multi-stage tests were conducted on a natural sodium bentonite, while varying both the specimen void ratio, e, and the solute concentration, cs, of the equilibrium sodium chloride (NaCl) solutions. The measured phenomenological parameters were interpreted through a mechanistic model, in which the electric charge of clay particles is taken into account via a single material parameter, [Formula: see text], referred to as the “solid charge coefficient”. A constant value of [Formula: see text] = 110 mmol/L was found to provide an accurate interpretation of the experimental data, at least within the investigated range of bentonite void ratios (3.33 ≤ e ≤ 4.18) and NaCl concentrations of the external bulk solutions (5 ≤ cs ≤ 90 mmol/L). The results support the hypothesis that both chemical osmosis and swelling pressure are macroscopic manifestations of the same interactions, which occur at the microscopic scale between the clay particles and the ions contained in the pore solution, and that both of them can be modelled through a single theoretical framework.

Effective Diffusion Coefficients and Thermal Stability of the Structure of Metallic Glass Fe48Co32P14B6

2020 ◽  
Vol 62 (12) ◽  
pp. 2258-2265 ◽  
Author(s):  
S. V. Vasiliev ◽  
V. I. Parfenii ◽  
E. A. Pershina ◽  
A. S. Aronin ◽  
O. V. Kovalenko ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Metallic Glass ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Effective Diffusion Coefficients ◽  
Thermal Stability Of

scholarly journals Modeling and thermodynamic properties of ‘bacaba’ pulp drying

2019 ◽  
Vol 23 (9) ◽  
pp. 702-708 ◽  
Author(s):  
Maria F. de Morais ◽  
José R. O. dos Santos ◽  
Marisângela P. dos Santos ◽  
Dyego da C. Santos ◽  
Tiago N. da Costa ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermodynamic Properties ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Thermal Conditions ◽  
Drying Process ◽  
Experimental Conditions ◽  
Effective Diffusion Coefficients ◽  
Drying Rates ◽  
Increasing Temperature

ABSTRACT This study aimed to dry ‘bacaba’ (Oenocarpus bacaba Mart.) pulp under different thermal conditions, fit different mathematical models to the dehydration curves, and calculate the diffusion coefficients, activation energy and thermodynamic properties of the process. ‘Bacaba’ fruits were meshed to obtain the pulp, which was dried at temperatures of 40, 50 and 60 °C and with thickness of 1.0 cm. Increase in drying temperature reduced the dehydration times, as well as the equilibrium moisture contents, and drying rates of 0.65, 1.04 and 1.25 kg kg min-1 were recorded at the beginning of the process for temperatures of 40, 50 and 60 °C, respectively. The Midilli’s equation was selected as the most appropriate to predict the drying phenomenon, showing the highest R2, lowest values of mean square deviation (MSD) and χ2 under most thermal conditions, and random distribution of residuals under all experimental conditions. The effective diffusion coefficients increased with increasing temperature, with magnitudes of the order of 10-9 m2 s-1, being satisfactorily described by the Arrhenius equation, which showed activation energy (Ea) of 37.01 kJ mol-1. The drying process was characterized as endergonic, in which enthalpy (ΔH) and entropy (ΔS) reduced with the increment of temperature, while Gibbs free energy (ΔG) was increased.

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