Enhanced remediation of radioactive soil via synergistic foam flotation-acid washing process in a single reactor

Abstract

This study presents an integrated single-reactor system for the remediation of soil contaminated with cesium (Cs+) and cobalt (Co2*) by combining foam flotation and acid washing. Initially, foam flotation with cetyltrimethylammonium bromide (CTAB) selectively separated clay particles, which bound to CTAB via electrostatic interaction. Subsequently, soil washing using oxalic acid and CTAB effectively desorbed residual Cs+ and Co2* from the sand-sized fraction. Based on these results, we evaluated the applicability of the integrated foam flotation-soil washing process to the decontamination of Cs- and Co-soil. When treating an artificially contaminated soil containing 40.9 mg/kg of Cs+ and 34.9 mg/kg of Co2*, the fine particle flotation process alone lowered their concentrations to 26.8 and 23.3 mg/kg, respectively. Further in-situ acid treatment reduced Cs+ to 8.5 mg/ kg for (79.3 % removal) and Co2* to 1.3 mg/kg (96.2 % removal). These results demonstrate that the integrated single-reactor approach enables selective separation of fine particles and enhanced desorption of radionuclides. While this study serves as a proof-of-concept using artificially contaminated soil, it offers a practical and scalable solution, warranting further investigation on field-contaminated radioactive soil.