Abstract
Long-root Eichhornia crassipes, an aquatic plant with extensive root systems, has demonstrated potential in remediating eutrophicated water bodies. However, improper disposal of large quantities of discarded plants post-remediation can easily cause secondary pollution. In this study, rapidly recoverable magnetic carbon quantum dots (MCQDs) were greenly synthesized via hydrothermal treatment of long-root Eichhornia crassipes and subsequent coupling with Fe(3)O(4) nanoparticles. Adsorption experiments demonstrated that MCQDs displayed a commendable adsorption capacity for various heavy metals in municipal wastewater under the synergistic effect of CODs and Fe(3)O(4). Mechanistic analyses revealed that the adsorption involved chemical binding with oxygen-containing functional groups and amino groups on the surface of MCOQs. The saturated MCQDs were efficiently recovered within 5 min using an applied magnetic field, offering a practical solution for nanoparticle recovery. This study provides valuable insights into the green resource utilization of Long-root Eichhornia crassipes based on CQD technology. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40643-026-01064-x.