A multifunctional core-shell CoFe₂O₄@ZIF-67 nanocomposite for simultaneous detection and removal of Pb²⁺ in water

To address the challenge of integrated detection and removal of toxic Pb²⁺ from water, a novel magnetic core-shell nanocomposite, CoFe₂O₄@ZIF-67, was developed. This design synergistically combines the superparamagnetism of the CoFe₂O₄ core for rapid separation with the highly porous and coordinatively active ZIF-67 shell for efficient Pb²⁺ capture. As an electrochemical sensor, the composite exhibited exceptional performance for Pb²⁺ detection, with a wide linear range (0.01-40 µM), an ultra-low detection limit (9.37 nM), high sensitivity (32.17 µA µM^-1 cm^-2), and reliable applicability in real water samples (recoveries: 99.51-103.42%). Simultaneously, as an adsorbent, it achieved a high Langmuir capacity of 200 mg g^-1, with adsorption kinetics and isotherms following pseudo-second-order and Freundlich models, respectively, confirming a spontaneous and multilayer process. This work provides an effective dual-functional platform, demonstrating the great potential of magnetic MOF composites in advanced water treatment technologies.