Effect of solution pH and ion concentrations on leaching of silicate glass
For simple alkali silicate glasses, alkali leaching appears to be controlled by the structure and water content of hydrated silica gel phases formed on the glass surface and by the ion exchange properties of the silanol groups present in those phases. When elements other than alkali cations or silica are present in the leachate, the only species observed to be adsorbed by the gel layer are simple cations or positively charged colloids. Contrary to results reported for silica gel, and for reasons not yet understood, molecular hydrolysis products do not appear to interact with the glass except at low concentration levels. Alkali leaching from the glass appears to be unaffected by the presence of other elements in the leachate unless these elements can significantly change the structure of the gel layer. Solution analyses for Na suggest that Fe(III) in solution can accelerate Na leaching by almost an order of magnitude, presumably by removing silica from the surface gel, making it a more open structure which can support more rapid diffusion. Lead can inhibit leaching if it coats the glass with a coherent lead carbonate film of colloidal particles. These leaching effects are consistent with leaching results reported for the complex nuclear waste glass PNL-7668 in solutions containing Pb or Fe, showing that the results obtained for simple alkali silicate glasses can be extrapolated to explain the behavior of more complex systems.
- Research Organization:
- Sandia National Labs., Albuquerque, NM
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5945129
- Report Number(s):
- CONF-821107-Pt.1
- Journal Information:
- Mater. Res. Soc. Symp. Proc.; (United States), Journal Name: Mater. Res. Soc. Symp. Proc.; (United States) Vol. 15; ISSN MRSPD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
36 MATERIALS SCIENCE
360604* -- Materials-- Corrosion
Erosion
& Degradation
ALKALI METALS
DATA
DISPERSIONS
DISSOLUTION
ELEMENTS
EXPERIMENTAL DATA
GLASS
INFORMATION
LEACHATES
LEACHING
METALS
MIXTURES
NUMERICAL DATA
PH VALUE
QUANTITY RATIO
SEPARATION PROCESSES
SODIUM
SOLUTIONS