Colloid Formation During the Interaction of HLW Glass with Interstitial Clay Water

1996 ◽  
Vol 465 ◽  
Author(s):  
J. Wei ◽  
P. Van Iseghem
Keyword(s):  
Size Distribution ◽  
Surface Area ◽  
Glass Surface ◽  
Waste Glass ◽  
Complexation Reaction ◽  
Different Temperatures ◽  
Colloid Formation ◽  
Solution Volume

ABSTRACTDuring the reaction of HLW glass with interstitial clay water at different temperatures with various ratios of glass surface area to solution volume (SA/V) and durations, Eu released from the glass forms predominantly Eu-humate colloids (organic colloids) by a complexation reaction. The size distribution and stability of Eu-humate colloids have been characterized. It is likely that inorganic colloids which are mainly composed of Si, Al and Ca are generated from the corrosion of waste glass by a nucleation reaction.

The Effects of Surface Area to Solution Volume on Waste Glass Leaching

1983 ◽  
Vol 62 (2) ◽  
pp. 151-158 ◽  
Author(s):  
L. R. Pederson ◽  
C. Q. Buckwalter ◽  
G. L. McVay
Keyword(s):  
Surface Area ◽  
Waste Glass ◽  
Glass Leaching ◽  
Solution Volume

Glass Surface area to Solution Volume Ratio and its Implications to Accelerated Leach Testing

1982 ◽  
Vol 15 ◽  
Author(s):  
Larry R. Pederson ◽  
Charles Q. Buckwalter ◽  
Gary L. Mcvay ◽  
B. Lynn Riddle
Keyword(s):  
Solid State ◽  
Surface Area ◽  
Glass Surface ◽  
Volume Ratio ◽  
Leaching Tests ◽  
Soluble Glass ◽  
State Diffusion ◽  
Dissolved Silicon ◽  
Glass Leaching ◽  
Solution Volume

ABSTRACTLeaching tests of PNL 76–68 glass in deionized water have been performed using the standard MCC-l static leaching procedure but with varied glass surface area to solution volume ratios (SA/V). It was found that leaching could be strongly influenced by the SA/V ratio, due largely to an effect of silicon solubility limitations. The conclusion that solubility and not solid state diffusion is most important in regulating leaching rates is supported by (1) the similarities in depth profiles of all soluble glass components with none depleted to depths greater than that of silicon despite vastly different solid state diffusivities, and (2) the lack of dependence of leaching rates on reaction layer thicknesses. To more directly examine the influence of dissolved silicon on glass leaching rates, leaching tests were performed in silicic acid solutions and in two actual groundwaters. As expected, leaching rates of all soluble glass components were reduced by amounts roughly proportional to the silicon saturation fraction. Since solubility modifies leaching rates in all but very dilute solutions, short-term tests at high SA/V values can be used to predict solution concentrations for long-term tests at low SA/V values, although reaction layers formed are not of the same thickness. Glass leaching data for a range of leaching times and SA/V values can be represented by a single curve when plotted versus the product of SA/V and time. However, the use of SA/V variations may have limited usefulness in accelerated leach testing for multicomponent systems. Events such as silica colloid and certain alteration phase formations modify the above relationship.

Effects of Surface Area-to-Solution Volume Ratio on Chemical Durability of Nuclear Waste Glasses

1989 ◽  
Vol 176 ◽  
Author(s):  
X. Feng ◽  
I. L. Pegg ◽  
Y. Guo ◽  
AA. Barkatt ◽  
P. B. Macedo
Keyword(s):  
Surface Area ◽  
Nuclear Waste ◽  
Volume Ratio ◽  
Fixed Time ◽  
Waste Glass ◽  
Corrosion Mechanism ◽  
General Tendency ◽  
Savannah River ◽  
Report Data ◽  
Solution Volume

ABSTRACTWe report data on the relationship between nuclear waste glass durability, as measured by leachate concentrations and leach rates, and the ratio of glass surface area to solution volume, S/V. The study includes West Valley non-radioactive production glasses (SF6 and SF10), West Valley glasses containing U and Th designed at CUA (WVCM47, WVCM50, and WVCM59), Savannah River SRLTDS-131 glass, and Hanford waste glass HW-39 (for which existing literature data is used). While some of these glasses show departures of leachate concentrations from simple (S/V)t scaling others conform well. The departures are, in all cases, most evident at high values of S/V. It is therefore important, therefore to understand how glass composition determines which corrosion mechanism is dominant in order to assess the region of validity of extrapolations based on (S/V)t scaling. While leach rates show a general tendency to decrease with S/V and time, exceptions are evident for the less durable glasses which show minima and maxima in the S/V-dependence at fixed time.

Carbon Nanofibers Grown In Situ on Porous Glass

2017 ◽  
Vol 50 ◽  
pp. 1-17
Author(s):  
M. Alejandra Mazo ◽  
Javier Sanguino ◽  
Aitana Tamayo ◽  
Juan Rubio
Keyword(s):  
Surface Area ◽  
Carbon Nanofibers ◽  
Porous Glass ◽  
Glass Surface ◽  
Acid Leaching ◽  
Glassy Matrix ◽  
Broad Size Distribution ◽  
Different Temperatures ◽  
20 Nm

Carbon nanofibers (CNFs) were grown in situ on porous glass at different temperatures and times using a Ni acetate catalyst and CH4/N2 as a carbon source. The porous glass was obtained by acid leaching of phase separated borosilicate glass, which generates a broad size distribution of mesopores (≈20 nm). Subsequent impregnation with Ni acetate reduces the pore size to ≈ 4 nm but also creates new micropores, thus increasing the surface area. During thermal treatment the surface area decreases as temperature rises, mainly due to shrinkage of the glassy matrix; however new pores are created at ≈ 70 nm (mainly at 600 oC) associated to the generation of CNFs on the glass surface, indicating this temperature offers the best conditions. The CNFs grow inside and fill in the micro-mesopores in the porous glass. They do not grow at 500 oC as the Ni acetate is not transformed into metallic Ni. Ni deactivation occurs at temperatures over 700 oC, thus reducing the formation of CNFs. At 1000 oC the degradation of CH4 leads to a thickening of the CNFs. The thermal degradation of the CNFs occurs in two steps, the first (360-416oC) corresponding to CNFs grown on the glass surface and the second (518-649oC) to CNFs grown inside the glass pores. Treatment times over 2 h lead to the deactivation of Ni, pore shrinkage and hence lower CNF yields.

Time-Dependence of Volatilization of 137Cs and 106Ru Over High-Level Waste Glass in a Canister

1991 ◽  
Vol 257 ◽  
Author(s):  
Hiroshi Kamizono ◽  
Susumu Muraoka
Keyword(s):  
Differential Equation ◽  
Surface Layer ◽  
Simple Model ◽  
Time Dependence ◽  
Surface Area ◽  
Glass Surface ◽  
Waste Glass ◽  
High Level Waste ◽  
Forward Rate ◽  
High Level

ABSTRACTVolatility of 137Cs and 106Ru at 600ºC over high-level waste glass in a canister is numerically analyzed. The time-dependence of normalized concentrations of each radionuclide is traced by a differential equation based on a simple model consisting of competitive forward and backward steps. It is assumed that, as time proceeds, a surface layer forms on the glass and serves as a protective barrier against volatilization. It is found that the forward rate of volatilization for 137Cs is about 140 times greater than that of 106Ru at 600ºC. The effects of the glass surface area and plenum volume on the concentration excursion inside the canister are closely estimated by the differential equation.

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

scholarly journals Air filtration improvement of konjac glucomannan-based aerogel air filters through physical structure design

2021 ◽  
Author(s):  
Hong Qian ◽  
Ying Fang ◽  
Kao Wu ◽  
Hao Wang ◽  
Bin Li ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Physical Structure ◽  
Structure Design ◽  
Air Filtration ◽  
Air Filters ◽  
Air Filter ◽  
Purification Time

Abstract This study presents two methods to improve the air filtration performance of konjac glucomannan (KGM)-based aerogel air filters through physical structure design by changing the pore-size distribution and the surface area, using an air purifier. Results indicated that KGM-based aerogels had a comparable filtration effect with the commercial air filter with a longer purification time. This purification time could be shortened by over 50%, by changing the pore-size distribution from large size to small size or increase the surface area with the fold structure. This should boost the development of polysaccharide-based aerogel used as the air filter.

The relationship between geotechnical index properties and the pore-size distribution of compacted clayey silts

2015 ◽  
Vol 22 (6) ◽  
Author(s):  
Nazile Ural
Keyword(s):  
Specific Surface ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Correlation Coefficients ◽  
Liquid Limit ◽  
Index Properties

AbstractIn this study, the relationships between geotechnical index properties and the pore-size distribution of compacted natural silt and artificial soil mixtures, namely, silt with two different clays and three different clay percentages (10%, 20%, and 40%), were examined and compared. Atterberg’s limit tests, standard compaction tests, mercury intrusion porosimetry, X-ray diffraction, scanning electron microscopy (SEM) analysis, and Brunauer-Emmett-Teller specific surface analysis were conducted. The results show that the liquid limit, the cumulative pore volume, and specific surface area of artificially mixed soils increase with an increase in the percentage of clay. The cumulative pore volume and specific surface area with geotechnical index properties were compared. High correlation coefficients were observed between the specific areas and both the liquid limit and the plasticity index, as well as between the cumulative pore volume and both the clay percentage and the

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