Synthesis and characterization of magnetic Fe3O4@SiO2-MIL-53(Fe) metal-organic framework and its application for efficient removal of arsenate from surface and groundwater

In recent years, Metal-organic frameworks (MOFs) have received significant attention to adsorb arsenic from aqueous media. In this study, magnetic Fe3O4 @SiO2-MIL-53(Fe) was prepared and characterized by XRD, SEM, EDX, FTIR, VSM, and BET techniques. The synthesized Fe3O4 @SiO2-MIL-53(Fe) was successfully applied to remove arsenate with a maximum adsorption capacity of 70.1 mg/g. The adsorbent capability was tested in different pH, co-existing ions, and trace arsenate concentrations, and their particles were easily separated from the solution by an external magnetic field. Adsorption and VSM tests showed that the adsorbent capacity and magnetic properties were preserved after four cycles. The adsorption process obeyed the pseudo-second-order model and the experimental data well fitted with Langmuir monolayer isotherm. Immobilization of Fe3O4 @SiO2 nanoparticles into the MIL-53(Fe) structure was reduced iron ions leaching to the solution. For the first time, the Fe3O4 @SiO2-MIL-53(Fe) composite was successfully used to remove arsenic from contaminated surfaces and groundwater.