Phytoremediation of soil co-contaminated with uranium and chromium by sunflower (Helianthus annuus L.) enhanced with slow-release composite chelating agent (EDTA/ammonium citrate)

Abstract

BACKGROUND: Soil in uranium mining areas is contaminated by uranium and associated heavy metals, posing a significant threat to human health and ecological security. Chelating agent assisted phytoremediation is a cost-effective and ecologically friendly remediation approach for uranium and associated heavy metals contaminated soil. In this work, a novel slow-release composite chelating agent (SRCMC-g-CMCD-EDTA/AC) was fabricated using carboxymethyl chitosan-graft-carboxymethyl-β-cyclodextrin (CMC-g-CMCD) as a slow-release carrier and EDTA/ammonium citrate (AC) as a composite chelating agent through the spray drying method, which was used for phytoremediation of soil co-contaminated with uranium and chromium. RESULTS: CMC-g-CMCD exhibited superior slow-release performance for both EDTA and AC in comparison with CMC and CMCD. When applied to soil contaminated with uranium (U) and chromium (Cr), SRCMC-g-CMCD-EDTA/AC effectively regulated the release of U and Cr. Sunflowers (Helianthus annuus L.) grown in treated soil showed a significant increase in U and Cr uptake by 70.55% and 35.55%, respectively, and reduced leaching losses by 34.88% and 37.42%. CONCLUSION: SRCMC-g-CMCD-EDTA/AC not only assists in the phytoremediation of soil co-contaminated with U and Cr but also reduces the risk of leaching into groundwater during the soil phytoremediation process. SRCMC-g-CMCD-EDTA/AC-assisted phytoremediation technology was an effective and environmentally friendly remediation means for the removal of U and heavy metals from contaminated soils in uranium mining areas. © 2024 Society of Chemical Industry (SCI).