Aromatic polymer dual-confined magnetic metal-organic framework microspheres enable highly efficient removal of dyes, heavy metals, and antibiotics

Abstract

Considering the diversified threats to freshwater, it is challenging to achieve highly efficient treatment of wastewater containing organic dyes, antibiotics, and heavy metal ions. Herein, we put forward a series of magnetic adsorbents based on an aromatic polymer-mediated dual-confinement strategy. The aromatic polymer plays double roles in both encapsulating magnetic Fe3O4 nanoparticles and providing nucleation sites for the metallic and organic precursors of zeolitic imidazolate framework-8 (ZIF-8). The internal and external confinement enables stable magnetic response and subsequent epitaxial growth of ZIF-8, resulting in recyclable metal–organic framework (MOF) microspheres as adsorbents. The BET specific surface area of the MOF microspheres is up to 1002.0 m2·g−1, and the maximum adsorption capacities of malachite green (MG), tetracycline (TC), and Cu(II) predicted by the Langmuir isotherm at 303.15 K are 1823.60, 909.09 and 2305.44 mg‧g−1, respectively. The MOF microspheres exhibit excellent broad-spectrum adsorption capacities for the three pollutants in neutral and strongly alkaline environments. In addition, the overall adsorption performances remain positive after 5 cycles of adsorption–desorption experiments accompanied by nearly invariable saturation magnetization. This study develops a competitive magnetic adsorbent for the multi-targeted removal of dyes, heavy metals, and antibiotics, which can balance the cost-effective preparation, impressive adsorption capacities, and high cycling stabilities toward the remediation of complex wastewater.