Development of the Synthetic Rock Technique for the Immobilization of Iodine: Kinetics of the Alumina Matrix Dissolution under High Alkaline Conditions

ABSTRACTIodine filters expended after nuclear fuel reprocessing contain radioactive iodine (I-129), almost all of which exists as silver iodide (AgI). The synthetic rock technique is a solidification treatment technique using hot isostatic press (HIP), in which the alumina adsorbent base material is synthesized to form a dense solidified material (synthetic rock), and I-129 is physically confined in the form of AgI in the alumina matrix. Thus, it is necessary to understand the matrix dissolution behavior to evaluate the iodine release behavior.Experiments involving the dissolution of the matrix were carried out under various temperatures (35–70 °C) and pH values (10–12.5) that reflect the disposal conditions. The results of the experiments showed that the dissolution rate of Al visibly increases with temperature and pH. The dissolution rate constant was calculated from the initial data assuming the dissolution of the matrix as a primary reaction. The logarithmic rate constant showed a good linear correlation with the pH and the reciprocal of temperature. The 27Al-NMR analysis of the solutions of the dissolved matrix showed that the major chemical species present in the solutions was Al(OH)4-. This indicated that the dissolution of the matrix can be described by the following equation: Al2O3 + 2OH- + 3H2O → 2Al(OH)4-. Subsequently, the empirical equation of the rate of dissolution of the matrix as a function of the temperature and pH was derived. It will be used to evaluate the iodine release behavior from the synthetic rock.

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Congruent and Incongruent Radionuclide Release During Matrix Dissolution of Partly Oxidized High Burnup Spent Fuel

MRS Proceedings ◽

10.1557/proc-663-417 ◽

2000 ◽

Vol 663 ◽

Cited By ~ 2

Author(s):

A. Loida ◽

B. Grambow ◽

H. Geckeis

Keyword(s):

Dissolution Rate ◽

Masking Effect ◽

Dissolution Behavior ◽

Spent Fuel ◽

Ph Values ◽

Fe Powder ◽

The Matrix ◽

Order Of Magnitude ◽

The Impact

ABSTRACTWith respect to the assessment of the long-term behavior of the waste form spent fuel it is of high importance to study in particular the UO2 matrix dissolution behavior and the associated release/retention of radionuclides in contact with groundwater. During long term fuel storage, fuel oxidation may not be avoided. Main issue of this work is to identify the impact on the corrosion of partly oxidized fuel of environmental conditions such as (1) the nature of solution contacting the matrix, the (2) presence/absence of CO2, (3) fixed pH values within a range between pH 7- pH 11, and (4) the presence/absence of corroding container material (Fe-powder). Dissolution tests with powdered oxidized spent fuel in various granite waters, and NaCl-brine resulted in matrix dissolution rates in the same order of magnitude for all investigated media (ca.5×10−4/d). The presence of CO2 and fixed pH values (pH 5 – 11) was without a distinct effect. The independence of the dissolution rate of the oxidized fuel matrix upon the nature of solution, pCO2, fixed pH values (5-11) can probably be explained by a masking effect of radiolysis. In presence of Fe powder the matrix dissolution rate was found to be slowed down by a factor of ca. 20, associated with strong retention effects of radionuclides.

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Dynamic Emergence of Nanostructure and Transport Properties in Perfluorinated Sulfonic Acid Ionomers

10.26434/chemrxiv.12302693.v1 ◽

2020 ◽

Author(s):

Adlai Katzenberg ◽

Debdyuti Mukherjee ◽

Peter J. Dudenas ◽

Yoshiyuki Okamoto ◽

Ahmet Kusoglu ◽

...

Keyword(s):

Rate Constant ◽

Sulfonic Acid ◽

Mass Fraction ◽

Gas Permeability ◽

Transport Processes ◽

Segmental Mobility ◽

The Matrix ◽

Swelling Rate ◽

Ion Conducting ◽

Perfluorinated Sulfonic Acid

Limitations in fuel cell electrode performance have motivated the development of ion-conducting binders (ionomers) with high gas permeability. Such ionomers have been achieved by copolymerization of perfluorinated sulfonic acid (PFSA) monomers with bulky and asymmetric monomers, leading to a glassy ionomer matrix with chemical and mechanical properties that differ substantially from common PFSA ionomers (e.g., Nafion™). In this study, we use perfluorodioxolane-based ionomers to provide fundamental insights into the role of the matrix chemical structure on the dynamics of structural and transport processes in ion-conducting polymers. Through in-situ water uptake measurements, we demonstrate that ionomer water sorption kinetics depend strongly on the properties and mass fraction of the matrix. As the PFSA mass fraction was increased from 0.26 to 0.57, the Fickian swelling rate constant decreased from 0.8 s-1 to 0.2 s-1, while the relaxation rate constant increased from 3.1×10-3 s-1 to 4.0×10-3. The true swelling rate, in nm s-1, was determined by the chemical nature of the matrix; all dioxolane-containing materials exhibited swelling rates ~1.5 - 2 nm s-1 compared to ~3 nm s-1 for Nafion. Likewise, Nafion underwent relaxation at twice the rate of the fastest-relaxing dioxolane ionomer. Reduced swelling and relaxation kinetics are due to limited matrix segmental mobility of the dioxolane-containing ionomers. We demonstrate that changes in conductivity are strongly tied to the polymer relaxation, revealing the decoupled roles of initial swelling and relaxation on hydration, nanostructure, and ion transport in perfluorinated ionomers.

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Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0048 ◽

2017 ◽

Vol 62 (1) ◽

pp. 321-326 ◽

Cited By ~ 13

Author(s):

J. Górka

Keyword(s):

Thermomechanical Processing ◽

Control Process ◽

Base Material ◽

Structural Defects ◽

Accelerated Cooling ◽

Internal Stresses ◽

Mechanical Control ◽

Thin Foils ◽

Precipitation Processes ◽

The Matrix

Abstract This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by dispersive (Ti,Nb)(C,N) precipitates (being between several and less than twenty nanometers in size). In arc welding, depending on a welding method and linear energy, an increase in the base material in the weld is accompanied by the increased concentration of hardening microagents in the weld. The longer the time when the base material remains in the liquid state, the greater the amount of microagents dissolved in the matrix. During cooling, such microagents can precipitate again or remain in the solution. An increase in welding linear energy is accompanied by an increase in the content of hardening phases dissolved in the matrix and, during cooling, by their another uncontrolled precipitation in the form of numerous fine-dispersive (Ti,Nb)(C,N) precipitates of several nm in size, leading to a dislocation density increase triggered by type 2 internal stresses.

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Improving Biomaterials from a Cellular Point of View

MRS Proceedings ◽

10.1557/proc-0925-bb03-02 ◽

2006 ◽

Vol 925 ◽

Cited By ~ 2

Author(s):

Venu Gopal Varanasi ◽

T. Vallortigara ◽

P. M. Loomer ◽

E. Saiz ◽

A. P. Tomsia ◽

...

Keyword(s):

Dissolution Rate ◽

Cell Number ◽

Point Of View ◽

Dissolution Behavior ◽

Ti Alloy ◽

Bioactive Glasses ◽

Culture Studies ◽

Cell Numbers ◽

Number Increase

ABSTRACTBioactive glasses (6P55) used for coating Ti/Ti-alloy were tested for their in vitro behavior in a comparative study with commercial Bioglass™ (45S5) and commercial Ti alloy (Ti6Al4V). In vitro testing included pH and dissolution rate determination in simulated body fluid (SBF) along with in vitro cyto compatibility testing. It was seen in this work that 6P55 and 45S5 had similar dissolution behavior, demonstrating t½ dependence and maximum pH of approximately 8.1 after 10 days of immersion. This pH was reduce by 0.2 0.4 pH units when the in vitro V:A ratio was increased from 1 to 3. The dissolution rate of these glasses approached 0 after additional immersion tests after 15 days and the pH stablilized at less than 7.5. Cell culture studies showed that both glasses behaved in similar fashion after 16 hours in culture. Both glasses had an increase in cell numbers of close to 200-250%, whereas Ti6Al4V had a less pronounced cell number increase (∼ 180%)

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In Situ Produced MMC Layer by Laser Melt Injection

Materials Science Forum ◽

10.4028/www.scientific.net/msf.649.61 ◽

2010 ◽

Vol 649 ◽

pp. 61-66

Author(s):

Zoltán Kálazi ◽

Viktória Janó ◽

Gábor Buza

Keyword(s):

Carbon Content ◽

Composite Layer ◽

Pure Titanium ◽

Base Material ◽

Titanium Content ◽

Steel Sample ◽

Low Carbon ◽

The Matrix ◽

Ti Powder

Tungsten (W) based alloy composite layer reinforced with TiC particles has been successfully prepared on unalloyed steel sample by LMI technology. In order to obtain in situ produced TiC reinforcement, pure titanium has been introduced to the melt pool. WC powder was added for increasing the carbon content of the layer in order to avoid the softening of the matrix (with low carbon content) during TiC formation. The present study aims to investigate the optimum amount of injected WC and Ti powder to improve wear resistance and hardness of the layer. Samples were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The maximum hardness of the layer has been reached ~900HV in case of 2-4wt% of titanium content. Ti has been collected all of the carbon from the matrix when titanium content was 9,6wt%, which resulted that the austenite and (Fe,W)6C phases have been disappeared. Only α-Fe and TiC phases were presented in the layer. The hardness of the layer reduced to the hardness of the base material.

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Dissolution behavior of chemically amplified resist for advanced mask- and NIL mold-making as studied by dissolution rate monitor

10.1117/12.681763 ◽

2006 ◽

Author(s):

Kazumasa Takeshi ◽

Kazuto Oono ◽

Yoshiyuki Negishi ◽

Daisuke Inokuchi ◽

Keishi Tanaka ◽

...

Keyword(s):

Dissolution Rate ◽

Dissolution Behavior ◽

Chemically Amplified ◽

Chemically Amplified Resist ◽

Mold Making

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Plasma-Spray-Forming of Alumina Matrix Composite Reinforced with Metal Thin Wire

Thermal Spray 2000: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2000p0619 ◽

2000 ◽

Author(s):

S. Sodeoka ◽

T. Inoue ◽

M. Suzuki

Keyword(s):

Plasma Spray ◽

Spray Forming ◽

Filament Winding ◽

Atmospheric Plasma ◽

Thin Wire ◽

Alumina Matrix ◽

Plasma Spray Forming ◽

Inconel 600 ◽

The Matrix ◽

The Wire

Abstract Alumina matrix composites reinforced with metal thin wire (Inconel-600) were successfully fabricated by plasma spray forming. The atmospheric plasma sprayed matrix layers and wire layers arranged by filament-winding technique were piled up alternately. Though the matrix and the wire were partially bonded only on the side which sprayed particles came flying to, a solid structure was obtained by this technique. Spraying in one direction perpendicular to the substrate made peculiar V-shape pores around the wires, but tilting the torch was effective to reduce the pores. The flexural strength of composite did not increase in spite of some crack deflections on the fracture surface. Owing to the wire pullout, however, the composite exhibited a remarkably higher apparent fracture energy than that of monolithic alumina ceramics.

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The Effect of PVP Molecular Weight on Dissolution Behavior and Physicochemical Characterization of Glycyrrhetinic Acid Solid Dispersions

Advances in Polymer Technology ◽

10.1155/2020/8859658 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Xiaoyu Sui ◽

Yan Chu ◽

Jie Zhang ◽

Honglian Zhang ◽

Huiyu Wang ◽

...

Keyword(s):

Molecular Weight ◽

Dissolution Rate ◽

Solid Dispersions ◽

Physicochemical Characterization ◽

Dissolution Behavior ◽

Enhancement Effect ◽

Glycyrrhetic Acid ◽

Equilibrium Solubility ◽

Drug Molecules ◽

Pvp K30

The effect of polyvinylpyrrolidone (PVP) as glycyrrhetic acid (GA) solid dispersions carrier at different molecular weights on the dissolution behavior and physicochemical properties was investigated. PVP-GA-SDs prepared with all four molecular weight PVPs displayed good enhancement of dissolution rate and equilibrium solubility compared with pure drug and corresponding physical mixtures. The results showed that the enhancement effect of molecular weight on dissolution rate and equilibrium solubility follows PVP K 30 > PVP K 60 > PVP K 17 > PVP K 15 . In addition, the dissolution rate and solubility of the SDs with a carrier-drug ratio of 8 : 1 were better than the samples of 4 : 1. The DSC and XRD patterns showed that the crystallization of GA in SDs prepared by PVP K30 and PVP K60 was significantly inhibited, and both were transformed to amorphous. Based on FTIR and Raman detection, a hydrogen-bond between PVP and drug molecules is formed. SEM results showed that there were no significant differences in the appearance of SDs prepared with four PVPs, and no crystalline morphology of GA was seen. In conclusion, the findings of this study demonstrated that the dissolution performance of the PVP-GA-SDs prepared by the solvent method is related to the molecular weight of PVP, and the change in the molecular weight of PVP does not cause a monotonic change in dissolution of GA. The samples with PVP K30 as the carrier have the best dissolution performance.

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Enhancing the Mechanical and Tribological Properties of Cellulose Nanocomposites with Aluminum Nanoadditives

Polymers ◽

10.3390/polym12061246 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1246

Author(s):

Shih-Chen Shi ◽

Tao-Hsing Chen ◽

Pramod Kumar Mandal

Keyword(s):

Tensile Strength ◽

Load Capacity ◽

Hydroxypropyl Methylcellulose ◽

Base Material ◽

Wear Test ◽

Barrier Properties ◽

Wear Volume ◽

Mechanical And Tribological Properties ◽

The Matrix ◽

Tribology Performance

Hydroxypropyl methylcellulose (HPMC) is a common hydrophilic and biodegradable polymer that can form films. This study incorporated aluminum nanoadditives as an enhancement reagent into a HPMC matrix. Mechanical properties of nanocompoistes, including the tensile strength and the elastic modulus, were analyzed with a nano-tensile tester. The incorporation of additives in HPMC films significantly enhances their mechanical and film barrier properties. Evidence of bonding between the additive and matrix was observed by Fourier-transform infrared spectrometer analysis. The additives occupy the spaces in the pores of the matrix, which increases the tendency of the pore to collapse and improves the chemical bonding between the base material and the additives. The incorporation of excess additives decreases the tensile strength due to ineffective collisions between the additives and the matrix. The wear test proves that the addition of nano-additives can improve the tribology performance of the HPMC composite while reducing the wear volume and the friction. Bonding between the nanoadditives and the matrix does not help release the nanoadditives into the wear interface as a third-body layer. The main reason to enhance the tribology performance is that the nanoadditives improve the load-capacity of the composite coating. This hybrid composite can be useful in many sustainability applications.

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Dissolution Kinetics of a Simple Analogue Nuclear Waste Glass as a Function of Ph, Time and Temperature

MRS Proceedings ◽

10.1557/proc-176-176 ◽

1989 ◽

Vol 176 ◽

Cited By ~ 8

Author(s):

Kevin G. Knauss ◽

William L. Bourcier ◽

Kevin D. McKeegan ◽

Celia I. Merzbacher ◽

Son N. Nguyen ◽

...

Keyword(s):

Dissolution Rate ◽

Rate Constant ◽

Rate Constants ◽

Dissolution Kinetics ◽

State Theory ◽

Alkaline Solutions ◽

Glass Dissolution ◽

Constant Ph ◽

Transport Control ◽

Dissolution Rate Constants

ABSTRACTWe have measured the dissolution rate of a simple five-component borosilicate glass (Na2O, CaO, Al2O3, B2O3, SiO2) using a flow-through system. The experiments were designed to measure the dissolution rate constant over the interval pH 1 through pH 13 at 3 temperatures (25°, 50° and 70°C). Dilute buffers were used to maintain a constant pH. Analyses of solutions and solid surfaces provided information that is used to develop a kinetic model for glass dissolution.Under all conditions we eventually observed linear dissolution kinetics. In strongly acidic solutions (pH 1 to pH 3) all components but Si were released in their stoichiometric proportions and a thick, Si-rich gel was formed. In mildly acidic to neutral solutions the gel was thinner and was both Si- and Al-rich, while the other components were released to solution in stoichiometric proportions. In mildly to strongly alkaline solutions all components were released to solution in stoichiometric proportions. By varying the flow rate at each pH we demonstrated a lack of transport control of the dissolution rate.The dissolution rates were found to be lowest at near-neutral pH and to increase at both low and high pH. A rate equation based on transition-state theory (TST) was used to calculate dissolution rate constants and reaction order with respect to pH over two pH intervals at each temperature. At 250C between pH 1 and pH 7 based on the Si release rate the log rate constant for glass dissolution (g glass/m20d) was −0.77 and the order with respect to pH was −0.48. Between pH 7 and pH 13 the log rate constant for glass dissolution was −8.1 and the order with respect to pH was +0.51. The measured simple glass dissolution rate constants compare very well with constants estimated by fitting the same TST equation to experimental results obtained for SRL-165 glass and to dissolution rate estimates made for synthetic basaltic glasses.

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