Core-Shell Ferromagnetic Nanorod Based on Amine Polymer Composite (Fe₃O₄@DAPF) for Fast Removal of Pb(II) from Aqueous Solutions

Heavy metal ion removal from wastewater constitutes an important issue in the water treatment industry. Although a variety of nanomaterials have been developed for heavy metal removal via adsorption, the adsorption capacity, removal efficiency, and material recyclability still remain a challenge. Here, we present novel Fe₃O₄@DAPF core-shell ferromagnetic nanorods (CSFMNRs) for the removal of Pb(II) from aqueous solutions; they were prepared by the facile surface modification of twin-like ferromagnetic Fe₃O₄ nanorods using a 2,3-diaminophenol and formaldehyde (DAPF)-based polymer. The crystallinity and structure of the Fe₃O₄ nanorods were confirmed via X-ray diffraction (XRD). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed the core-shell morphology and composition of the materials. Pb(II) removal using the prepared Fe₃O₄@DAPF CSFMNRs was assessed, and comparable adsorption capacities (83.3 mg g^-1) to the largest value were demonstrated. A thermodynamic study of the adsorption clearly indicated that the adsorption was exothermic and spontaneous. Due to the ferromagnetic properties with a high saturation magnetization value (56.1 emu g^-1) of the nanorods, the nanorods exhibited excellent reusability with one of the fastest recovery times (25 s) among reported materials. Therefore, the Fe₃O₄@DAPF CSFMNRs can serve as recyclable adsorbent materials and as an alternative to commonly used sorbent materials for the rapid removal of heavy metals from aqueous solutions.