Phytoremediation of soil co‐contaminated with uranium and chromium by sunflower (<i>Helianthus annuus</i> L.) enhanced with slow‐release composite chelating agent (<scp>EDTA</scp>/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 (SR CMC‐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), SR CMC‐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 SR CMC‐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. SR CMC‐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).