Develop Reusable Carbon Sub‐Micrometer Composites with Record‐High Cd(II) Removal Capacity

Abstract Cd(II)‐induced pollution across diverse water bodies severely threatens ecosystems and human health. Nevertheless, achieving ultra‐efficient and cost‐effective treatment of trace amounts of heavy metals remains a major challenge. Herein, the novel carbon sub‐micrometer composites (CSMCs) supported Fe⁰@γ‐Fe₂O₃ core‐shell clusters nanostructures are designed and synthesized through a series of universally applicable methods. Research data on adsorption behavior clearly revealed that resorcinol/formaldehyde 1.25‐basic ferric acetate (RF‐1.25BFA) and RF‐1.25BFA‐540 have surprising adsorption capacities. Employing the adsorbent dosage of 0.025 g L⁻¹, the adsorption capacities for 10 mg L⁻¹ Cd(II) reached 400.00 mg g⁻¹ with ultrafast adsorption kinetics, alongside theoretical maximum adsorption capacities for Cd(II) of 1108.87 and 1065.06 mg g⁻¹ using 0.025 g L⁻¹ adsorbent, respectively, setting a new record‐high level. Additionally, they demonstrated exceptional stability and reusability, maintaining Cd(II) removal efficiency above 95% even after 15 adsorption–desorption cycles. Importantly, this study is the first to unveil a new ultrafast successive two‐step enrichment–hydrolysis adsorption mechanism for Cd(II) removal, emphasizing the critical role played by iron clusters nanostructures in constructing a high‐alkalinity adsorption microenvironment on the surface of the materials. The findings reported pioneered a new avenue for the rational design of high‐performance environmental remediation materials, aiming to overcome the limitations of traditional mine drainage treatment.