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

• Magnetic separation and acid washing were used to remove U from fine soil. • The highest U removal was achieved using two-step acid washing with 1.0 M H 2 SO 4 . • PEI-coated γ-Fe 2 O 3 magnetic NPs effectively separated U-enriched silt and clay. • Combined methods reduced soil radioactivity below the clearance level of 1.0 Bq/g. 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-Fe 2 O 3 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 H 2 SO 4 , HNO 3 , Na 2 CO 3 , and NaHCO 3 . The highest U removal efficiency was achieved using 1.0 M H 2 SO 4 , 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.