Biogenic jarosite coating as an innovative passivator for acidic uranium residue stabilization using...

Uranium release from mineral leaching residues presents a significant environmental hazard, requiring effective and sustainable stabilization strategies. This study proposes a bio-mediated surface passivation strategy using Acidithiobacillus ferrooxidans to generate a biogenic jarosite coating that effectively immobilizes uranium in the residues. A highly crystalline, dense coating particles with 33.3 % jarosite was synthesized under optimized conditions (pH 2.0, 30°C, particle size < 0.074 mm), as evidenced by SEM analysis, and High score plus refinement. Furthermore, microstructural analysis (Nano-CT, SEM, EDS, FTIR, XPS, and XRD), coupling the Scherrer and Hall-Petch equations, revealed a crystallite size of 34.41 nm and a high residual stress (average σ × 10³ = 4.76), leading to significantly enhanced corrosion resistance, barrier properties, and mechanical performance. Additionally, uranium chemical and acid release tests demonstrated the coating reduced uranium release by > 99.3 %, decreasing from 104 μg/L/d in untreated residues to 0.0601 μg/L/d; meanwhile the coating also maintained a stable pH of 4.02 ± 0.15 over 30 days. Finally, a possible mechanism model is proposed for Acidithiobacillus ferrooxidans-driven biopassivation of uranium residues. These results highlight the significant potential of biogenic jarosite coating as a promising and sustainable strategy for the long-term stabilization of acidic uranium residues, and facilitating responsible radioactive waste management.