On the effect of Al on alumino-borosilicate glass chemical durability

Abstract

The chemical durability of borosilicate glass used to confine nuclear wastes is known to vary nonlinearly with their composition, making glass dissolution rate predictions difficult. Here, we focus on the effect of Al, an important oxide of these materials. The initial and residual glass dissolution rates were investigated through experiments conducted at 90 °C and pH 9. Our results show that low Al content glasses dissolve initially faster than glasses with higher Al content, but quickly achieve a lower residual rate due to the rapid formation of a more passivating gel. Nevertheless, the high Al content gel will eventually achieve passivation with a slower reorganization. The strengthening effect of Al on the Si-O bond hydrolysis will result in more stable gels, suggesting that slightly higher Al content in the gel will improve nuclear high-level waste glass durability in geological disposal conditions.

Research on the Properties of Wasteforms after Direct Involvement of Uranium-Containing Silica Gel in Glass Network Formation

“…The binding energy of [AlO 4 ] tetrahedron was about 73.4–74.5 eV, slightly lower than the binding energy of [AlO 6 ] octahedron, around 74.1–75.1 eV. , Generally, Al exists in two forms in glass: [AlO 4 ] (BE = 74.78 eV, fwhm = 1.19) as a network former and [AlO 6 ] (BE = 73.97 eV, fwhm = 1.17) as a network outer body. It had been reported that the chemical durability of the glass in water, HCl, and NaOH aqueous solutions was significantly enhanced after incorporating Al 3+ into the oxide glass network . Since the relative peak intensities of [AlO 4 ] and [AlO 6 ] in the FT-IR were both extremely weak, XPS analysis was used to determine the ratio of [AlO 4 ]/[AlO 6 ].…”