Lead(II) uptake by aluminium based magnetic framework composites (MFCs) in water

The recent combination of Metal-Organic Frameworks (MOFs) and magnetic nanoparticles has shown their potential as a composite material in practical applications including drug delivery, catalysis and pollutant sequestration. Here, we report for the first time the preparation of a robust magnetic nanocomposite material based on an aluminium MOF (MIL-53) and iron oxide nanoparticles for the uptake of lead(II) ions. Different aminofunctionalized MIL-53 MOFs were prepared by increasing the 2-aminoterephthalic/terephthalic acid ratio. The composite materials were tested to determine the sequestration capability of heavy metals from various solvents (methanol, DMSO and water), pH (2, 7, 12) and a range of Pb(II) concentrations (10-8000 ppm). The magnetic composite based on MIL-53 showed remarkable capacity to sequester Pb(II) ions from water (up to 492.4 mg g-1 of composite), the highest recorded for a MOF sorbent system to date. While the MOF played a crucial role in the efficient heavy metal uptake, the magnetic nanoparticles allowed the prompt collection of the sorbent from solution. The triggered release of Pb(II) was investigated using an alternating magnetic field. The exceptional adsorption capacity and the response to the magnetic field make this class of innovative functional material a promising candidate for environmental remediation technologies.