Pilot scale application of ²²⁶Ra-contaminated soil leaching remediation

To address the issue of soil contamination caused by associated elements during the extraction and processing of radioactive minerals, this study employed two types of chemical leaching methods, one based on organic acids and the other on carbonates, to remediate radium-contaminated soil. Large-scale soil slurry reactors were used in field experiments to investigate the effects of acidic and alkaline leaching agents on the removal of ²²⁶Ra from naturally contaminated soil, and the optimal operational conditions were determined. The combined use of organic acids, salts and solubilizers has demonstrated high removal rates of radionuclide on a laboratory scale. Pilot scales revealed that using FeCl₃, oxalic acid, NaClO₂, and HEDP, or Na₂CO₃, NaHCO₃, H₂O₂, and deep eutectic solvent (DES) as leaching agents achieved the best remediation outcomes for radium-contaminated soil. Under optimal conditions, the radium removal efficiencies of the two leaching systems reached 93.02% and 90.66%, respectively. Characterization analyses using X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), and scanning electron microscope (SEM) demonstrated that the chemical leaching methods are both safe and reliable, effectively removing radium while having minimal impact on the soil's original structure. Additionally, these methods have the potential to replenish soil nutrients and restore its functional use.