Preparation of magnetic framework composites Fe₃O₄@MIL-100(Fe) and adsorption of lead in water

Magnetic metal–organic frameworks are attracting attention as excellent adsorbents due to abundant pore structures and easy separation. Two Fe₃O₄@MIL-100(Fe) (Fe₃O₄: ferroferric oxide, MIL: Materials of the Institut Lavoisier) compounds were synthesized in dimethylformamide (DMF) and ethanol (EtOH), denoted as Fe@MIL-DMF and Fe@MIL-EtOH. Carboxyl group functionalization of Fe₃O₄ suggested that sodium borohydride can promote more carboxyl groups decorated on the surface of Fe₃O₄ and resulted in more MIL-100(Fe) shell. Meanwhile, solvent DMF encouraged a greater MIL-100(Fe) layer coverage on Fe₃O₄ surface than EtOH, leading to a higher surface area and a greater adsorption ability for lead ion (Pb²⁺). Adsorption experiments displayed a monolayer absorption and Pb²⁺ was adsorbed by electrostatic interaction and coordination.

Magnetic metal-organic frameworks Fe₃O₄@MIL-100(Fe) composites were synthesized in DMF and EtOH. Fe@MIL-DMF exhibited a higher surface area and a greater adsorption ability for Pb²⁺