Insight into the influence mechanism of chloride ions towards in-situ electric-induced uranium incorporation into magnetite

Abstract

The application of electrochemical methods for incorporating uranium into the magnetite lattice has demonstrated efficacy and durability in remediating radioactive contamination. However, the impact of different ions, particularly electrolyte ions, on this process remains unclear. Herein, we successfully achieved simultaneous magnetite crystallization and uranium incorporation within an electrochemical system using an iron anode. Chloride ions have been identified as having a pivotal role in the generation of ferrous ions via pitting corrosion, thereby establishing an advantageous reducing environment that promotes the transformation of γ-FeOOH to magnetite. Unlike the surface adsorption process of γ-FeOOH, magnetite predominantly eradicates uranium through an incorporation mechanism. Consequently, the existence of chloride ions markedly boosts the effectiveness of uranium elimination and the stability of the resultant substance. Specifically, under conditions of a pH of 5 and a chloride ions concentration of 18 mM, uranium removal reaches nearly 100%. Additionally, findings from uranium leaching experiments indicate that γ-FeOOH removed 25.4% stable, 63.57% metastable, and 11.03% unstable uranium, while magnetite removed 60.35% stable, 24.81% metastable, and 14.84% unstable uranium. This research offers insight into the potential role of electrolyte ions in facilitating in-situ electric-induced uranium incorporation.