Electrokinetics, Adsorption and Colloid Study of Simulated Nuclear Waste Glasses Leached in Aqueous Solutions

1984 ◽  
Vol 44 ◽  
Author(s):  
Cheng T. Lee ◽  
D. E. Clark
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Glass Surface ◽  
Charged Particles ◽  
Electrostatic Repulsion ◽  
Surface Layers ◽  
Short Term ◽  
Chloride Solutions ◽  
Zeta Potentials ◽  
Glass Surfaces

AbstractZeta potentials of SRL-131-29.8% TOS simulated nuclear waste glasses leached in D.I. water, Al, Ca, Mg, and Zn chloride solutions at 90°C were measured as a function of leaching time. For short term leaching, the adsorption of Ca, Mg, Zn and Al reverses the glass surface potential from negative to positive. Colloids were found to be stable in D.I. water and AICl3 solutions after leaching, presumably due to the electrostatic repulsion between the glass surface and similarly charged particles. Colloids were not found in Mg, Zn or Ca chloride solutions after leaching; instead, a relatively thick metasilicate surface layer was formed on glass surfaces leached in these solutions. The concentration of Si in solution is reduced by the formation of these surface layers.

Role of Surface Layers in the Leaching Behavior of Glass

1988 ◽  
Vol 125 ◽  
Author(s):  
B.K. Zoitos ◽  
D.E. Clark
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Surface Composition ◽  
Analytical Techniques ◽  
Surface Layers ◽  
Leaching Behavior ◽  
Leach Rate ◽  
Layer Analysis ◽  
Nuclear Waste Glass

ABSTRACTResults are presented from a two-year dynamic leach test of nuclear waste glass under conditions designed to simulate those of the Stripa granite repository. Solution and surface analytical techniques were used to assess the glass leach rate as well as surface composition and morphology. Glass leach rates were observed to decrease by a factor of two during the first six months. This effect is attributed to the formation of a protective surface layer. Analysis of this layer shows it to be rich in silicon and iron and depleted in lithium, sodium and boron. It was also found that the layer is subject to dissolution.

Secondary Phase Formation and the Microstructural Evolution of Surface Layers During Vapor Phase Alteration of the French Son68 Nuclear Waste Glass at 200 °C

1995 ◽  
Vol 412 ◽  
Author(s):  
W. L. Gong ◽  
R. C. Ewing ◽  
L. M. Wang ◽  
E. Vernaz ◽  
J. K. Bates ◽  
...  
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Vapor Phase ◽  
Rare Earths ◽  
Waste Glass ◽  
Transition Elements ◽  
Surface Layers ◽  
Crystalline Phases ◽  
Developed Surface ◽  
Nuclear Waste Glass

AbstractThe SON68 inactive “R7T7” composition is the French reference glass for the LWR nuclear waste glass. Vapor phase alteration was used to accelerate the reaction progress of glass corrosion and to develop the characteristic suite of secondary, alteration phases. Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six inactive R7T7 waste glasses which were altered in the presence of saturated water vapor (200 °C) for 91, 241, 908, 1000, 1013, and 1021 days. The AEM samples were examined in cross-section (lattice-fringe imaging, microdiffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered with a thin altered rind. The layer became thicker with time: 0.5μm for 22 days; 4 μm for 91 days; 6 μm for 241 days; 10 μm for 908 days; 26 μm for 1013 days; and <35μm for 1021 days. The composite alteration layer of the SON68 samples is at least four time less thick than that of the SRL 131 glass composition.Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. Two crystalline phases, Ag2TeO3 and (Ca,Sr)Mo3O9(OH)2, were found within the inner zones of surface layers, and they must have nucleated in situ, indicating that Ag, Te, Sr, and Mo can be retained within the surface layer. The majority of the surface layer volume is composed of two morphologically and chemically different structures: one consists of well-crystallized fibrous smectite aggregates occurring along with cavities, the A-domain; and the other consists of poorlycrystallized regions containing needle-like smectite (montmorillonite) crystallites, a silica-rich amorphous matrix, and possibly ZrO2 particles, the B-domain. The retention of rare-earths and Zr mostly occurred within B-domains and that of transition elements, such as Zn, Cr, Ni, and Mn, in A-domains. The recrystallization of poorly-crystallized B-domains into well-crystallized Adomains may influence the long-term behavior of rare-earths, Zr, and transition elements. The mechanism of surface layer formation during vapor phase alteration is discussed based on the cross-sectional AEM studies of surface layers of the SON68 waste glasses.

The Properties of Refined Glasses with Aluminum Hydroxide Nano-Molecules

2015 ◽  
Vol 227 ◽  
pp. 47-50
Author(s):  
Marcin Drajewicz ◽  
Maciej Pytel ◽  
Paweł Rokicki ◽  
Marek Góral
Keyword(s):  
Aluminum Hydroxide ◽  
Glass Surface ◽  
Inorganic Compounds ◽  
Surface Layers ◽  
Edx Analysis ◽  
Sem Observation ◽  
Calcium Silicon ◽  
Glass Surfaces ◽  
Glass Properties

New refining technology of soda – calcium – silicon glass surfaces with inorganic compounds nanomolecules has been presented in the study. In order to determine modification of the glass surface SEM observation and EDX analysis have been carried out. The glass samples were subjected to the UV-VIS, photo-elasticity and ellipsometry examinations. From obtained results follows, that refining of the glass surface by nanopowder aluminum hydroxide compounds provides forming of very thin surface layers. This type of modification improves physical glass properties. As the example results of microhardness refined glass are presented in the article.Keywords: glass, surface, nanoparticles, refining

Effect of Surface Layers on the Dissolution of Nuclear Waste Glasses

1993 ◽  
Vol 333 ◽  
Author(s):  
Shi-Ben Xing ◽  
Andrew C. Buechele ◽  
Ian L. Pegg
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Glass Composition ◽  
Reaction Rates ◽  
Surface Layers ◽  
Linear Effect ◽  
Glass Dissolution ◽  
Important Challenge ◽  
Saturation Effects ◽  
Glass Powders

ABSTRACTExplanation of the striking non-linear effect of glass composition on the aqueous dissolution represents an important challenge to existing dissolution mechanisms. Surface layers that are formed during glass dissolution may play an important role in this effect. One chemically reactive and one less-reactive nuclear waste glass (leachate concentrations differ by about a factor of 10) were reacted in deionized water. Two types of glass powders were used: Type A powders were pristine glass powders; Type B powders were the glass powders which had been reacted for 120 days to develop the surface layers. Both the solution concentrations and the surface layers were investigated. The experimental observations indicate that: (i) There is a range of glass compositions over which small differences in composition lead to large changes in both reaction rates and surface layer thickness; and (ii) The reaction rate is strongly affected by the formation of the surface layer (the layer appears to be protective) and cannot be explained in terms of saturation effects alone. The findings are contrary to the conclusion of a previous study and serve to highlight the inadequacy of existing dissolution models predicated on an overly simplistic mechanism, especially with regard to glass composition effects.

The Surface Morphology and Optical Properties of Refined Glasses with Inorganic Nano-molecules

2015 ◽  
Vol 34 (3) ◽  
Author(s):  
Marcin Drajewicz ◽  
Maciej Pytel ◽  
Paweł Rokicki ◽  
Marek Góral
Keyword(s):  
Optical Properties ◽  
Surface Modification ◽  
Glass Surface ◽  
Inorganic Compounds ◽  
Refining Process ◽  
Surface Layers ◽  
Calcium Silicon ◽  
Glass Surfaces ◽  
Physical And Chemical ◽  
Glass Properties

AbstractNew refining technology of soda-calcium-silicon glass surfaces with inorganic compounds nano-molecules has been presented in the study. In order to determine modification of the glass surface SEM observation and EDX analysis have been carried out. The UV-VIS, photo-elasticity and ellipsometry examinations were carried out on glass samples. The results of investigations that have been conducted show that refining process of the glass surface by use of nanopowder inorganic compounds deposited electrostatically on glass surface provides forming of very thin (about 50 nm) surface layers [1]. This method of surface modification improves physical and chemical glass properties. In this paper results of microhardness test of refined glass were also presented.

scholarly journals Small time scale plankton structure variations at the entrance of a tropical eutrophic bay (Guanabara Bay, Brazil)

2012 ◽  
Vol 60 (4) ◽  
pp. 405-414 ◽  
Author(s):  
Mariana Guenther ◽  
Isabel Lima ◽  
Glenda Mugrabe ◽  
Denise Rivera Tenenbaum ◽  
Eliane Gonzalez-Rodriguez ◽  
...  
Keyword(s):  
Surface Layer ◽  
Photosynthetic Efficiency ◽  
Great Influence ◽  
Small Time ◽  
Guanabara Bay ◽  
Short Term ◽  
Mesozooplankton Biomass ◽  
Trophic Pathways ◽  
Se Brazil ◽  
Almost All

The dynamics of the plankton compartments at the entrance of Guanabara Bay (SE Brazil) were assessed during a short-term temporal survey to estimate their trophic correlations. Size-fractioned phytoplankton (picoplankton: < 2µm, nanoplankton: 2-20µm and microplankton: > 20µm) biomass and photosynthetic efficiency, composition and abundance of the auto-and heterotrophic nano-and microplankton, and mesozooplankton were evaluated at a fixed station for 3 consecutive days at 3-h intervals, in the surface and bottom (20m) layers. The variability of almost all plankton compartments in the surface layer was directly dependent on temperature, indicating the great influence of the circulation at the entrance of the bay on plankton structure. In the surface layer, the mesozooplankton seems to be sustained by both autotrophic nano-and picoplankton, this last being channeled through the microzooplankton. Near the bottom, both auto-and heterotrophic microplankton are probably supporting the mesozooplankton biomass. Our findings thus suggest that the entrance of Guanabara bay presents a multivorous food web, i.e., a combination of both grazing and microbial trophic pathways.

Glass Surface Layer Density by Neutron Depth Profiling

2012 ◽  
Vol 3 (2) ◽  
pp. 137-143 ◽  
Author(s):  
Cory L. Trivelpiece ◽  
John J. Petrunis ◽  
Carlo G. Pantano ◽  
R. Gregory Downing
Keyword(s):  
Surface Layer ◽  
Glass Surface ◽  
Depth Profiling ◽  
Neutron Depth Profiling ◽  
Layer Density

Stresses in the Surface Layer and Hydrogen Absorption and Diffusion in Cavitation Condition

2014 ◽  
Vol 225 ◽  
pp. 131-138
Author(s):  
Jarosław Chmiel ◽  
Jolanta Baranowska ◽  
Roman Jędrzejewski ◽  
Arkadiusz Rzeczycki
Keyword(s):  
Surface Layer ◽  
Stress State ◽  
Hydrogen Absorption ◽  
Surface Layers ◽  
Fem Modeling ◽  
And Diffusion

Cavitation attack in liquids generated a various states of stresses in surface layers of metals. Differences in stress state effects on hydrogen absorption activated by the cavitation implosion. Results of XRD investigation and FEM modeling shows on inhomogenity of process.

About U(t) form of pH-dependence of glass corrosion rates at zero surface to volume ratio

2015 ◽  
Vol 1744 ◽  
pp. 153-161 ◽  
Author(s):  
Michael I. Ojovan ◽  
William E. Lee
Keyword(s):  
Nuclear Waste ◽  
Low Temperatures ◽  
Ph Dependence ◽  
Effective Diffusion ◽  
Volume Ratio ◽  
Surface Layers ◽  
Near Surface ◽  
Numerical Examples ◽  
Corrosion Rates ◽  
Glass Corrosion

ABSTRACTThe pH-dependence of glass corrosion rates has a well-known U-shaped form with minima for near-neutral solutions. This paper analyses the change of U-shaped form with time and reveals that the pH dependence evolves even for solutions that have pH not affected by glass corrosion mathematically corresponding to a zero surface to volume ratio. The U(t) dependence is due to changes of concentration profiles of elements in the near-surface layers of glasses in contact with water and is most evident within the initial stages of glass corrosion at relatively low temperatures. Numerical examples are given for the nuclear waste borosilicate glass K-26 which is experimentally characterised by an effective diffusion coefficient of caesium DCs = 4.5 10-12 cm2/day and by a rate of glass hydrolysis in non-saturated groundwater as high as rh = 100 nm/year The changes of U-shaped form need to be accounted when assessing the performance of glasses in contact with water solutions.

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