Impact of V ₂ O ₅ on the Dissolution Behavior of Sodium Aluminoborosilicate‐Based Model Nuclear Waste Glass

ABSTRACT

Understanding how vanadium oxide (V ₂ O ₅ ) influences the dissolution behavior of nuclear waste glasses is essential for optimizing their waste loading and long‐term durability. In this work, a series of sodium aluminoborosilicate‐based model glasses—(100− x ) (30Na ₂ O–5Al ₂ O ₃ –15B ₂ O ₃ –50SiO ₂ )— x V ₂ O ₅ , where x = 0, 2.5, and 5 mol.%—were synthesized to investigate the structural and chemical origins of V ₂ O ₅ ‐dependent dissolution behavior. Glass corrosion experiments were conducted in both deionized (DI) water and 0.1 M Tris‐HCl buffer (pH 7) at 65°C for 7 days. The results revealed that all glasses dissolved incongruently, with Na, B, and V leaching more rapidly than Si and Al. The incorporation of V ₂ O ₅ produced a statistically insignificant change in the dissolution kinetics of glasses in Tris‐HCl, although dissolution in Tris‐HCl was consistently faster than in deionized water. XPS and XANES analyses confirmed that vanadium exists primarily as V ⁵⁺ (tetrahedral [V ⁵⁺ O ₄ ] ³⁻ ), with a minor fraction of V ⁴⁺ (square‐pyramidal [V ⁴⁺ O ₅ ] ⁶⁻ ). However, quantitative discrepancies between the two techniques highlight differences in their surface and bulk sensitivities. The minimal impact of V ₂ O ₅ on the dissolution kinetics of glasses in Tris‐HCl is rationalized by a structural model in which highly charged [V ⁵⁺ O ₄ ] ³⁻ units remain largely decoupled from the silicate network and scavenge Na ⁺ from the aluminoborosilicate network for charge‐compensation, leading to competing effects that offset one another during glass corrosion.