Extractive decontamination of cesium-containing soil using a biodegradable aminopolycarboxylate chelator

The radiocesium released from the anthropogenic sources or radiological activities tends to migrate in the least-mobile soil fraction over time. The water-only washing is thus less-efficient for the decontamination of cesium-laden soils. In the current work, a technique for the washing remediation of cesium-contaminated soils using aminopolycarboxylate chelators (APCs) has been evaluated, with the inclusion of an additive. The extraction variables have been optimized using simulated soils of ultisol, leaf-mold, and andosol-types, which represents the typical Japan-origin soils from playgrounds, forests, and farmlands. The performances of typical APCs (e.g., DTPA and EDTA) were compared with that of biodegradable alternatives (EDDS, GLDA, or HIDS) for the treatment of cesium-contaminated soils. The impact of different pH conditions, ranging between acidic to basic, was studied while the soil to the extractant ratio was maintained at 1:10. A greater degree of cesium release from leaf-mold and andosol soils was observed with the HIDS, a biodegradable APC. The cesium-dissolution ability of HIDS has been further enhanced by the addition of NH4Cl salt in the mix as attributable to the exchange of Cs+ and NH4+ ions. The optimized variables for chelator-assisted washing have been applied to treat the real-contaminated soils from Fukushima, Japan to induce up to 40.4 ± 5.7% extraction of radiocesium from the solid matrix.