Magnetic responsive metal-organic frameworks nanosphere with core-shell structure for highly efficient removal of methylene blue

Magnetic metal-organic frameworks (MOFs) nanospheres with high specific surface area and sensitive response were fabricated by a step-by-step assembly strategy. Fe3O4 nanospheres were firstly prepared by the traditional hydrothermal method. They were then modified by poly(acrylic acid) (PM) through distillation-precipitation polymerization. The core-shell MOFs were prepared using Fe3O4@PAA nanoparticles as templates through a versatile step-by-step self-assembly strategy. The shell thickness of the MOFs could also be easily controlled by tuning the number of assembly cycles. The obtained materials were used as adsorbent to remove methylene blue from wastewater. Results demonstrated that the obtained hybrid materials had higher adsorption capacity and could be easily recycled from liquid media by an external magnetic field because of the presence of a magnetic core and could be reused after been washed by ethanol (1% HCl). Most importantly, the surface functional group could also be easily changed by alternating the organic ligands in the assembly process based on different adsorbates. (C) 2015 Elsevier B.V. All rights reserved.