An improved thermodynamic approach to the stability of multi‐component silicate glasses in aqueous solutions

Abstract

A rate equation is developed by which the dissolution rates of multicomponent silicate glasses in diluted aqueous solutions can be calculated as a function of pH, CO, partial pressure, and salinity. Gibbs free energies of hydration are derived by treating the aqueous solution as a diluted system of aqueous species of the various cations in the glass, and by treating the glass as a mixture of the constitutional phases taken from its basic phase diagram.Beside the free energies, the amounts of H+ and OHabsorbed at the glass surface are taken into account as rate determining factors. Calculated dissolution rates of silica, A type., E type, rock, and slag glass fibres agree with experimental values within +30% on a linear scale.

Chemical Durability of Oxide Glasses in Aqueous Solutions: A Review

“…Both the geochemical and the thermodynamic approach to glass corrosion depend on a quantitative determination of this equilibrium. For systems far from any saturation limit, the solution may be presented in terms of independently coexisting aqueous oxide species 18 ; for a comprehensive review on related data, see 19 . More complex situations comprising the formation of amorphous or crystalline precipitates may be treated with the help of available software tools, e.g., Roine and colleagues 20–23 …”

“…In the first version of the model, 73 the value for the term X ·exp(− E A / RT ) was assessed as 5.5 × 10 −12 mol Si·(cm 2 ·s) −1 . Later, it was shown 13,18 for more than 400 data sets that the term involving Δ G hydr has to be extended by a factor ɛ, i.e., it has to be taken as exp(−ɛΔ G hydr /RT) with ɛ≈0.3. The constant ɛ varies with the molar fraction of silica x (SiO 2 ) like ɛ=0.2/ x (SiO 2 ).…”

“…In accordance with the work by Boksay and Bouquet 84 and by Baucke, 17 f ( i ) can be described by a Langmuir‐type surface adsorption term allowing for the adsorption of H + , OH − , and other charged species at the glass surface. Such a concept has also been used by 18,85 . In this work, a surface adsorption term is essential to correctly capture the pH dependence of glass dissolution as well as its dependence on the concentration of salts in the aqueous system.…”

“…Much additional information is obtained from experiments performed in water labeled by isotopes 2 H 5 D, or 18 O, or both. 43,47,[49][50][51] In soda-lime glasses, the exchange ratio D:Na is found to assume values between 1 and 3.…”

Corrosion of Glass

“…For borosilicate and lead-rich glasses, deviations from linearity were interpreted as resulting from different structural roles of boron in the glass and were corrected [79]. If solution hydrolysis and complexation of dissolved glass constituents as well as surface complexation constants are taken into account, the corrosion rates of silicate glass fibers can be accurately described in the pH range 1-12 [80]. An alternative model is the structural bond strength model [193].…”