Magnetic nanocomposite for lead (II) removal from water

A magnetic perovskite-spinel oxide nanocomposite synthesized through a sol-gel self-combustion process is used for the first time as an adsorbent to remove toxic heavy metals (i.e., Pb²⁺). The synthesized LaFeO₃:CoFe₂O₄ ((LFO)₁:(CFO)_x) (x = 0.11-0.87) nanocomposites possess good stability, abundant oxygenated active binding sites, and unique structural features, making them suitable for removing divalent Pb²⁺ ions. Scanning electron microscopy, X-ray diffraction, BET surface area, magnetization measurements, zeta-potential analyses, and X-ray photoelectron spectroscopy were used to analyze the nanocomposites, and their structural changes after Pb²⁺ ions adsorption. Batch tests confirmed that (LFO)₁:(CFO)_x efficiently removes Pb²⁺ from water with a maximum adsorption capacity of 105.96 mg/g. The detailed quantitative study indicates that the interaction of hydroxyl groups with Pb²⁺ ions occurs through electrostatic interactions and complex formation. We also demonstrate a new ring-magnetic separator system that allows magnetic separation of the toxic ions at a higher speed compared to traditional block magnets. The unique structure, high porosity, large specific surface area, and oxygenated functional groups of (LFO)₁:(CFO)_x nanocomposites make them promising materials for removal of heavy metal ions and possibly other environmental pollutants. This study provides a new approach to preparing nanocomposites of magnetic spinel ferrites with perovskite oxides for environmental applications.