Impacts of glass composition, pH, and temperature on glass forward dissolution rate
Nuclear waste glasses dissolve at the forward dissolution rate (rf) in very dilute aqueous solutions, which can isolate the impact of the glass composition from solution feedback and alteration product effects. While it has long been known that pH and temperature (T) strongly impact rf, the impacts of glass composition have remained uncertain. In this work, rf data from 19 nuclear waste glasses were used with the aim of identifying the effect of glass composition on rf. The rf values were modeled as: rf= k010–ηpHexp(-Ea/RT), with k0, η, Ea, and R, respectively, being the intrinsic rate constant, pH coefficient, apparent activation energy, and gas constant. However, no predictive correlation could be established between the individual model parameters (log[k0], η, and Ea) and glass composition for the glasses considered in this study, an outcome that was attributed to the strong positive correlation between the log[$$k_0$$] and Ea parameters. Therefore, a model was fitted directly to the combined rf from all 19 glasses. This approach showed that 90% of the variation in rf data could be accounted for solely by T and pH effects. Therefore, any composition effects must be relatively small. After normalizing for differences in pH and T, the only notable differences in rf between the glasses were found to correlate with variations in the fraction of glass forming tetrahedra contributed by tetrahedral boron, $$f$$([4]B), with an abrupt threshold at a high value of $$f$$([4]B) (~0.22), where higher rf are predicted with no discernable composition effects below the threshold.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Center for Performance and Design of Nuclear Waste Forms and Containers (WastePD); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC05-76RL01830; SC0016584
- OSTI ID:
- 1558199
- Alternate ID(s):
- OSTI ID: 1668036
- Report Number(s):
- PNNL-SA-131331
- Journal Information:
- npj Materials Degradation, Vol. 2, Issue 1; ISSN 2397-2106
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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