Alexandre Loukanov1,2
1Laboratory of Engineering NanoBiotechnology, Department of Eng. Geoecology, University of Mining and Geology “St. Ivan Rilski”, Sofia, Bulgaria, E-mail: a.loukanov@mgu.bg
2Department of Chemistry and Materials Science, National Institute of Technology, Gunma College, 580 Toriba, Maebashi, Gunma 371-8530 Japan, E-mail: loukanov@gunma-ct.ac.jp
ABSTRACT. Uranium contamination of mine water and groundwater represents a significant environmental challenge associated with mining activities, ore processing, and radioactive waste management. In this study, uranium removal from aqueous solutions was comparatively evaluated using zero-valent iron nanoparticles (ZVINs), ligand-functionalised magnetic nanoparticles, water works sludge (WWS), and apatite under near-neutral conditions. The results revealed substantial differences in uranium immobilisation behaviour among the investigated materials. Water works sludge and apatite exhibited rapid uranium removal and reached near-equilibrium within a relatively short period, whereas ZVINs demonstrated slower but sustained uranium uptake over extended reaction times. This behaviour suggests that uranium immobilisation in Fe⁰ systems is influenced by progressive nanoparticle aging and the formation of iron corrosion products. The observed trends are consistent with uranium immobilisation mechanisms previously reported for Fe⁰-based systems, including adsorption onto iron oxides and hydroxides, co-precipitation with corrosion products, and possible reductive transformation of U(VI). In addition, amino-functionalised magnetic nanoparticles coated with a silsesquioxane polymer exhibited effective uranium adsorption and enabled rapid magnetic separation from aqueous solutions. Treatment of a 0.040 M uranium solution reduced the uranium concentration to approximately 0.014 M after 24 h, corresponding to about 64–65% removal efficiency, whereas uncoated magnetic nanoparticles exhibited negligible adsorption. Equilibrium adsorption data analysed using the Langmuir model indicated adsorption behaviour consistent with a finite number of active binding sites and confirmed the affinity of the amino-functionalised surface toward uranyl species within the investigated concentration range. The comparative results demonstrate that iron-based nanomaterials, particularly magnetically recoverable systems, may provide useful approaches for uranium removal and recovery from contaminated water. Although the experiments were conducted under simplified laboratory conditions, the findings provide a basis for further investigations in more complex mine-water systems, including the effects of competing ions, pH variability, sorbent regeneration, and long-term stability of immobilised uranium species.
Key words: uranium removal; zero-valent iron nanoparticles; magnetic nanoparticles; uranium immobilisation; mine water remediation; iron corrosion products.
DOI: https://doi.org/10.58903/MPIG2661
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