Insight into silicate-glass corrosion mechanisms.

The remarkable chemical durability of silicate glass makes it suitable for a wide range of applications. The slowdown of the aqueous glass corrosion kinetics that is frequently observed at long time is generally attributed to chemical affinity effects (saturation of the solution with respect to silica). Here, we demonstrate a new mechanism and highlight the impact of morphological transformations in the alteration layer on the leaching kinetics. A direct correlation between structure and reactivity is revealed by coupling the results of several structure-sensitive experiments with numerical simulations at mesoscopic scale. The sharp drop in the corrosion rate is shown to arise from densification of the outer layers of the alteration film, leading to pore closure. The presence of insoluble elements in the glass can inhibit the film restructuring responsible for this effect. This mechanism may be more broadly applicable to silicate minerals.

[1]  J. Banfield,et al.  Leaching and reconstruction at the surfaces of dissolving chain-silicate minerals , 1993, Nature.

[2]  D. K. Smith,et al.  A Kinetic Model for Borosilicate Glass Dissolution Based on the Dissolution Affinity of a Surface Alteration Layer , 1989 .

[3]  T. Advocat,et al.  Thermochemistry of nuclear waste glasses: application to weathering studies , 2001 .

[4]  Jillian F. Banfield,et al.  The surface chemistry of dissolving labradorite feldspar , 1989 .

[5]  Werner Lutze,et al.  Scientific basis for nuclear waste management , 1979 .

[6]  H. Scholze.  Durability investigations on siliceous man-made mineral fibers: a critical review , 1988 .

[7]  R. Revie.  Uhlig's Corrosion Handbook 2nd edition , 2000 .

[8]  Susan L. Brantley,et al.  NMR evidence for formation of octahedral and tetrahedral Al and repolymerization of the Si network during dissolution of aluminosilicate glass and crystal , 2003 .

[9]  T. Advocat,et al.  Nature and role of natural alteration gels formed on the surface of ancient volcanic glasses (Natural analogs of waste containment glasses) , 2003 .

[10]  Philippe Barboux,et al.  Leaching of borosilicate glasses. I. Experiments , 2004 .

[11]  Rodney C. Ewing,et al.  Chemical corrosion of highly radioactive borosilicate nuclear waste glass under simulated repository conditions , 1990 .

[12]  R. Winston Revie,et al.  Uhlig's Corrosion Handbook , 2005 .

[13]  H. Scholze.  Glass-water interactions , 1988 .

[14]  Philippe Barboux,et al.  Leaching of borosilicate glasses. II. Model and Monte-Carlo simulations , 2004 .

[15]  Bernd Grambow,et al.  First-order dissolution rate law and the role of surface layers in glass performance assessment , 2001 .

[16]  A. Karamanov,et al.  Chemical durability of glasses obtained by vitrification of industrial wastes. , 2001, Waste management.

[17]  P. Frugier,et al.  Theoretical consideration on the application of the Aagaard–Helgeson rate law to the dissolution of silicate minerals and glasses , 2008 .

[18]  J. Avery.  Critical review. , 2006, The Journal of the Arkansas Medical Society.

[19]  V. A. Alekseyev,et al.  Change in the dissolution rates of alkali feldspars as a result of secondary mineral precipitation and approach to equilibrium , 1997 .

[20]  I. Ribet,et al.  Role and properties of the gel formed during nuclear glass alteration: importance of gel formation conditions , 2001 .

[21]  D. P. Trivedi,et al.  Single-pass flow-through experiments on a simulated waste glass in alkaline media at 40°C.: I. Experiments conducted at variable solution flow rate to glass surface area ratio , 2000 .

[22]  P. Aagaard,et al.  Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions; I, Theoretical considerations , 1982 .

[23]  C. Pantano,et al.  The influence of natural mineral coatings on feldspar weathering , 1998, Nature.

[24]  B. C. Bunker,et al.  Molecular mechanisms for corrosion of silica and silicate glasses , 1994 .

[25]  Robert C. Wolpert,et al.  A Review of the , 1985 .

[26]  Michael F. Hochella,et al.  Mineral-water interface geochemistry; an overview , 1990 .

[27]  J. Calo,et al.  The application of small angle scattering techniques to porosity characterization in carbons , 2004 .

[28]  A. Abdelouas,et al.  Water diffusion in the simulated French nuclear waste glass SON 68 contacting silica rich solutions: Experimental and modeling , 2006 .

[29]  Eric M. Pierce,et al.  Accelerated weathering of high-level and plutonium-bearing lanthanide borosilicate waste glasses under hydraulically unsaturated conditions , 2007 .

[30]  David E. Clark,et al.  Physical chemistry of glass surfaces , 1977 .

[31]  I. Pegg,et al.  Effect of Surface Layers on the Dissolution of Nuclear Waste Glasses , 1993 .

[32]  G. J. McCarthy,et al.  Scientific Basis for Nuclear Waste Management (Vol 1) , 1979 .

[33]  M. Hodson.  The influence of Fe-rich coatings on the dissolution of anorthite at pH 2.6 , 2003 .

[34]  J. Icenhower,et al.  Origins of Discrepancies Between Kinetic Rate Law Theory and Experiments in the Na 2 O-B 2 O 3 -SiO 2 System , 2002 .

[35]  Francis R. Livens,et al.  The kinetics and mechanisms of simulated British Magnox waste glass dissolution as a function of pH, silicic acid activity and time in low temperature aqueous systems , 2000 .

[36]  E. Teller,et al.  ADSORPTION OF GASES IN MULTIMOLECULAR LAYERS , 1938 .

[37]  D. Ghaleb,et al.  A mechanistic model for understanding nuclear waste glass dissolution , 1992 .

[38]  Kathryn L. Nagy,et al.  Chemical weathering rate laws and global geochemical cycles , 1994 .

[39]  K. Keil,et al.  Alteration of basalt glasses: implications for modelling the long-term stability of nuclear waste glasses , 1985 .

[40]  D. Ghaleb,et al.  Evidence for 6‐Coordinated Zirconium in Inactive Nuclear Waste Glasses , 2004 .

[41]  L. Pederson,et al.  The Relationship Between Reaction Layer Thickness and Leach Rate For Nuclear Waste Glasses , 1983 .

[42]  T. Chave,et al.  Solid state diffusion during nuclear glass residual alteration in solution , 2007 .

[43]  L. Kump,et al.  CHEMICAL WEATHERING ,A TMOSPHERIC CO 2 , AND CLIMATE , 2000 .

[44]  O. Glatter,et al.  19 – Small-Angle X-ray Scattering , 1973 .

[45]  Water confined in nanopores: its molecular distribution and diffusion at lower density , 2003 .

[46]  A. Lasaga.  Chapter 2. FUNDAMENTAL APPROACHES IN DESCRIBING MINERAL DISSOLUTION AND PRECIPITATION RATES , 1995 .

[47]  W. P. Freeborn,et al.  The Role of Boron in Monitoring the Leaching of Borosilicate Glass Waste Forms , 1984 .

[48]  B. Grambow,et al.  A General Rate Equation for Nuclear Waste Glass Corrosion , 1984 .

[49]  R. Conradt.  Chemical Durability of Oxide Glasses in Aqueous Solutions: A Review , 2008 .

[50]  T. Charpentier,et al.  Influence of zirconium on the structure of pristine and leached soda-lime borosilicate glasses : Towards a quantitative approach by 17O MQMAS NMR , 2008 .

[51]  T. Advocat,et al.  Long-term alteration mechanisms in water for SON68 radioactive borosilicate glass , 2001 .

[52]  J. A. Stone,et al.  Scientific basis for nuclear waste management , 1985 .

[53]  Eric H. Oelkers,et al.  General kinetic description of multioxide silicate mineral and glass dissolution , 2001 .

[54]  L. Hench,et al.  Solution effects on the surface reactions of a bioactive glass. , 1993, Journal of biomedical materials research.