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

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.