An innovative approach to remediation of uranium-contaminated fine soil using magnetic separation and chemical washing

Abstract

Uranium (U) contamination in soil, derived from industrial activities and nuclear facility operations, poses significant environmental and health risks. This study explores an innovative remediation approach combining physical separation and chemical washing to treat U-contaminated fine soil. Fine soil samples (< 0.2 mm) were subjected to a series of experiments focusing on the selective separation of silt and clay particles using PEI-coated γ-Fe₂O₃ magnetic nanoparticles followed by a two-step acid washing treatment. The magnetic separation effectively targeted negatively charged clay particles, utilizing strong electrostatic attraction to form flocs, which were then easily separated under a magnetic field. Two-step chemical washings were performed at room temperature to decontaminate the fine soil, employing H₂SO₄, HNO₃, Na₂CO₃, and NaHCO₃. The highest U removal efficiency was achieved using 1.0 M H₂SO₄, reducing the residual radioactivity to below the clearance level recommended by IAEA (< 1.0 Bq/g). This combined method proved highly effective, showing over 99% U removal efficiency for fine soils larger than 0.5 mm without significant soil loss. The research highlights the potential for integrating advanced material sciences into environmental remediation practices to mitigate the risks associated with U-contaminated soils.