Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory

Jonathan P. Icenhower; B. Peter McGrail; Wendy J. Shaw; Eric M. Pierce; P. Nachimuthu; David K. Shuh; Elsa A. Rodriguez; Jackie L. Steele

doi:10.1016/j.gca.2008.02.026

Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory

Jonathan P. Icenhower, B. Peter McGrail, Wendy J. Shaw, Eric M. Pierce, P. Nachimuthu, David K. Shuh, Elsa A. Rodriguez, Jackie L. Steele

Research output: Contribution to journal › Article › peer-review

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Abstract

The dissolution kinetics of five chemically complex and five chemically simple sodium silicate glass compositions (Na-Si±Al±B) were determined over a range of solution saturation values by varying the flow-through rates (1-100 mL/d) in a dynamic single-pass flow-through (SPFT) apparatus. The chemically complex borosilicate glasses are representative of prospective hosts for radioactive waste disposal and are characterized by relatively high molar Si/(Si + Al) and Na/(Al + B) ratios (>0.7 and >1.0, respectively). Analysis by X-ray absorption spectroscopy (XAS) indicates that the fraction of ^ivB to ⁱⁱⁱB (N₄) varies from 0.66 to 0.70. Despite large differences in bulk chemistry, values of δ²⁹Si peak shift determined by MAS-NMR varies only by about 7 ppm (δ²⁹Si = -94 to -87 ppm), indicating small differences in polymerization state for the glasses. Forward rates of reaction measured in dynamic experiments converge (average log₁₀ rate [40 °C, pH 9] = -1.87 ± 0.79 [g/(m² d)]) at high values of flow-rate (q) to sample surface area (S). Dissolution rates are independent of total Free Energy of Hydration (FEH) and this model appears to overestimate the impact of excess Na on chemical durability. For borosilicate glass compositions in which molar Na > Al + B, further addition of Na appears to stabilize the glass structure with respect to hydrolysis and dissolution. Compared to other borosilicate and aluminosilicate glasses, the glass specimens from this study dissolve at nearly the same rate (0-∼56×) as the more polymerized glasses, such as vitreous reedmergnerite (NaBSi₃O₈), albite, and silica. Dissolution of glass follows the order: boroaluminosilicate glass > vitreous reedmergnerite > vitreous albite > silica glass, which is roughly the same order of increasingly negative ²⁹Si chemical shifts. The chemical shift of ²⁹Si is a measure of the extent of bond overlap between Si and O and correlates with the forward rate of reaction. Thus, dissolution appears to be rate-limited by rupture of the Si-O bond, which is consistent with the tenants of Transition State Theory (TST). Therefore, dissolution at far from equilibrium conditions is dependent upon the speed of the rate-controlling elementary reaction and not on the sum of the free energies of hydration of the constituents of boroaluminosilicate glass.

Original language	English
Pages (from-to)	2767-2788
Number of pages	22
Journal	Geochimica et Cosmochimica Acta
Volume	72
Issue number	12
DOIs	https://doi.org/10.1016/j.gca.2008.02.026
State	Published - Jun 15 2008
Externally published	Yes

Funding

The XAS work was supported in part by the Nevada DOE EPSCoR State-National Laboratory Partnership under Grant No. DE-FG02-01ER45898. This work was also supported by the Director, Office of Science, Office of Basic Energy Sciences, for operation of the ALS and the Division of Chemical Sciences, Geosciences, and Biosciences of the aforementioned U.S. DOE office, both under Contract No. DE-AC03-76SF00098 at LBNL. The CUA work was supported by the DOE Office of River Protection through Duratek Inc. We thank D. Lindle, M. Laurenzi, D.M. McKeown, R.C.C. Perera for help with the XAS investigation. The authors thank Jeff Post and Paul Pohwat (Smithsonian Institution, Mineral Sciences Department) for supplying the mineral specimens used in the NEXAFS work. This study was financially supported through a grant from the US Department of Energy under Contract No. DE-FG07-01ER63295. We specifically thank Dr. Fredrick Mann for support and encouragement. We gratefully acknowledge the efforts of Matthew O’Hara and Christopher F. Brown in analyzing the effluent samples. Many thanks are also extended to Antoinette Owen for support of various phases of the experiments. We also credit the NMR and XAS work supported by W.J. Shaw and J.A. Franz, and D. Lindle, M. Laurenzi, D.M. McKeown, R.C.C. Perera, respectively.

Funders	Funder number
DOE Office of River Protection
Duratek Inc
Nevada DOE EPSCoR State-National Laboratory Partnership
Office of Basic Energy Sciences
US Department of Energy
Office of Science
Chemical Sciences, Geosciences, and Biosciences Division

UN SDGs

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10.1016/j.gca.2008.02.026

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Icenhower, J. P., McGrail, B. P., Shaw, W. J., Pierce, E. M., Nachimuthu, P., Shuh, D. K., Rodriguez, E. A., & Steele, J. L. (2008). Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory. Geochimica et Cosmochimica Acta, 72(12), 2767-2788. https://doi.org/10.1016/j.gca.2008.02.026

@article{2934be671303499e8ac84cf859bfdded,

title = "Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory",

abstract = "The dissolution kinetics of five chemically complex and five chemically simple sodium silicate glass compositions (Na-Si±Al±B) were determined over a range of solution saturation values by varying the flow-through rates (1-100 mL/d) in a dynamic single-pass flow-through (SPFT) apparatus. The chemically complex borosilicate glasses are representative of prospective hosts for radioactive waste disposal and are characterized by relatively high molar Si/(Si + Al) and Na/(Al + B) ratios (>0.7 and >1.0, respectively). Analysis by X-ray absorption spectroscopy (XAS) indicates that the fraction of ivB to iiiB (N4) varies from 0.66 to 0.70. Despite large differences in bulk chemistry, values of δ29Si peak shift determined by MAS-NMR varies only by about 7 ppm (δ29Si = -94 to -87 ppm), indicating small differences in polymerization state for the glasses. Forward rates of reaction measured in dynamic experiments converge (average log10 rate [40 °C, pH 9] = -1.87 ± 0.79 [g/(m2 d)]) at high values of flow-rate (q) to sample surface area (S). Dissolution rates are independent of total Free Energy of Hydration (FEH) and this model appears to overestimate the impact of excess Na on chemical durability. For borosilicate glass compositions in which molar Na > Al + B, further addition of Na appears to stabilize the glass structure with respect to hydrolysis and dissolution. Compared to other borosilicate and aluminosilicate glasses, the glass specimens from this study dissolve at nearly the same rate (0-∼56×) as the more polymerized glasses, such as vitreous reedmergnerite (NaBSi3O8), albite, and silica. Dissolution of glass follows the order: boroaluminosilicate glass > vitreous reedmergnerite > vitreous albite > silica glass, which is roughly the same order of increasingly negative 29Si chemical shifts. The chemical shift of 29Si is a measure of the extent of bond overlap between Si and O and correlates with the forward rate of reaction. Thus, dissolution appears to be rate-limited by rupture of the Si-O bond, which is consistent with the tenants of Transition State Theory (TST). Therefore, dissolution at far from equilibrium conditions is dependent upon the speed of the rate-controlling elementary reaction and not on the sum of the free energies of hydration of the constituents of boroaluminosilicate glass.",

author = "Icenhower, {Jonathan P.} and McGrail, {B. Peter} and Shaw, {Wendy J.} and Pierce, {Eric M.} and P. Nachimuthu and Shuh, {David K.} and Rodriguez, {Elsa A.} and Steele, {Jackie L.}",

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doi = "10.1016/j.gca.2008.02.026",

language = "English",

volume = "72",

pages = "2767--2788",

journal = "Geochimica et Cosmochimica Acta",

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Icenhower, JP, McGrail, BP, Shaw, WJ, Pierce, EM, Nachimuthu, P, Shuh, DK, Rodriguez, EA & Steele, JL 2008, 'Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory', Geochimica et Cosmochimica Acta, vol. 72, no. 12, pp. 2767-2788. https://doi.org/10.1016/j.gca.2008.02.026

TY - JOUR

T1 - Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions

T2 - Implications for Transition State Theory

AU - Icenhower, Jonathan P.

AU - McGrail, B. Peter

AU - Shaw, Wendy J.

AU - Pierce, Eric M.

AU - Nachimuthu, P.

AU - Shuh, David K.

AU - Rodriguez, Elsa A.

AU - Steele, Jackie L.

PY - 2008/6/15

Y1 - 2008/6/15

N2 - The dissolution kinetics of five chemically complex and five chemically simple sodium silicate glass compositions (Na-Si±Al±B) were determined over a range of solution saturation values by varying the flow-through rates (1-100 mL/d) in a dynamic single-pass flow-through (SPFT) apparatus. The chemically complex borosilicate glasses are representative of prospective hosts for radioactive waste disposal and are characterized by relatively high molar Si/(Si + Al) and Na/(Al + B) ratios (>0.7 and >1.0, respectively). Analysis by X-ray absorption spectroscopy (XAS) indicates that the fraction of ivB to iiiB (N4) varies from 0.66 to 0.70. Despite large differences in bulk chemistry, values of δ29Si peak shift determined by MAS-NMR varies only by about 7 ppm (δ29Si = -94 to -87 ppm), indicating small differences in polymerization state for the glasses. Forward rates of reaction measured in dynamic experiments converge (average log10 rate [40 °C, pH 9] = -1.87 ± 0.79 [g/(m2 d)]) at high values of flow-rate (q) to sample surface area (S). Dissolution rates are independent of total Free Energy of Hydration (FEH) and this model appears to overestimate the impact of excess Na on chemical durability. For borosilicate glass compositions in which molar Na > Al + B, further addition of Na appears to stabilize the glass structure with respect to hydrolysis and dissolution. Compared to other borosilicate and aluminosilicate glasses, the glass specimens from this study dissolve at nearly the same rate (0-∼56×) as the more polymerized glasses, such as vitreous reedmergnerite (NaBSi3O8), albite, and silica. Dissolution of glass follows the order: boroaluminosilicate glass > vitreous reedmergnerite > vitreous albite > silica glass, which is roughly the same order of increasingly negative 29Si chemical shifts. The chemical shift of 29Si is a measure of the extent of bond overlap between Si and O and correlates with the forward rate of reaction. Thus, dissolution appears to be rate-limited by rupture of the Si-O bond, which is consistent with the tenants of Transition State Theory (TST). Therefore, dissolution at far from equilibrium conditions is dependent upon the speed of the rate-controlling elementary reaction and not on the sum of the free energies of hydration of the constituents of boroaluminosilicate glass.

AB - The dissolution kinetics of five chemically complex and five chemically simple sodium silicate glass compositions (Na-Si±Al±B) were determined over a range of solution saturation values by varying the flow-through rates (1-100 mL/d) in a dynamic single-pass flow-through (SPFT) apparatus. The chemically complex borosilicate glasses are representative of prospective hosts for radioactive waste disposal and are characterized by relatively high molar Si/(Si + Al) and Na/(Al + B) ratios (>0.7 and >1.0, respectively). Analysis by X-ray absorption spectroscopy (XAS) indicates that the fraction of ivB to iiiB (N4) varies from 0.66 to 0.70. Despite large differences in bulk chemistry, values of δ29Si peak shift determined by MAS-NMR varies only by about 7 ppm (δ29Si = -94 to -87 ppm), indicating small differences in polymerization state for the glasses. Forward rates of reaction measured in dynamic experiments converge (average log10 rate [40 °C, pH 9] = -1.87 ± 0.79 [g/(m2 d)]) at high values of flow-rate (q) to sample surface area (S). Dissolution rates are independent of total Free Energy of Hydration (FEH) and this model appears to overestimate the impact of excess Na on chemical durability. For borosilicate glass compositions in which molar Na > Al + B, further addition of Na appears to stabilize the glass structure with respect to hydrolysis and dissolution. Compared to other borosilicate and aluminosilicate glasses, the glass specimens from this study dissolve at nearly the same rate (0-∼56×) as the more polymerized glasses, such as vitreous reedmergnerite (NaBSi3O8), albite, and silica. Dissolution of glass follows the order: boroaluminosilicate glass > vitreous reedmergnerite > vitreous albite > silica glass, which is roughly the same order of increasingly negative 29Si chemical shifts. The chemical shift of 29Si is a measure of the extent of bond overlap between Si and O and correlates with the forward rate of reaction. Thus, dissolution appears to be rate-limited by rupture of the Si-O bond, which is consistent with the tenants of Transition State Theory (TST). Therefore, dissolution at far from equilibrium conditions is dependent upon the speed of the rate-controlling elementary reaction and not on the sum of the free energies of hydration of the constituents of boroaluminosilicate glass.

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U2 - 10.1016/j.gca.2008.02.026

DO - 10.1016/j.gca.2008.02.026

M3 - Article

AN - SCOPUS:44549083602

SN - 0016-7037

VL - 72

SP - 2767

EP - 2788

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

IS - 12

ER -

Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory

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