Magnetic conjugated microporous polymer hollow spheres decorated with Fe3O4 nanoparticles for selective absorption and sterilization

Abstract

The efficient removal and elimination of microbes from water is of great technological significance for saving water resources and sustainable social development. Herein, we report the invention of novel magnetic conjugated microporous polymer hollow spheres (CMP-HSs@Fe₃O₄), which were synthesized by a Sonogashira–Hagihara coupling reaction using trichloroisocyanuric acid and ethynylbenzene as building blocks in the presence of SiO₂ nanoparticles, followed by the removal of the SiO₂ template and then decoration with Fe₃O₄ nanoparticles, for the absorption of antibiotics and the sterilization of microbes in wastewater. The hollow sphere structures of the conjugated microporous polymer hollow spheres (CMP-HSs) exhibited a diameter of roughly 400 nm and a spherical shell thickness of 8 nm. They exhibited high BET surface areas and pore volumes of 178.9 m² g⁻¹ and 0.411 cm³ g⁻¹ for CMP-1-HSs and 168.4 m² g⁻¹ and 0.484 cm³ g⁻¹ for CMP-2-HSs, with distinct porosity and good permeability. Interestingly, the hollow sphere structure and continuous channels of the CMP-HSs@Fe₃O₄ spheres allow the antibiotic molecules to easily permeate the CMP-HSs wall and to be absorbed in the sphere cavity, resulting in a high adsorption capacity (recoveries ranging from 86.5% to 99.1%). At the same time, the inherently bacteriostatic property of the CMPs, as well as their abundantly accessible external surface area, originating from their hollow sphere structure, for contact with bacteria, gives the CMP-HSs@Fe₃O₄ superior sterilization performance, i.e., for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the minimum inhibitory concentration (MIC) of CMP-HSs is 150 μg mL⁻¹. Moreover, CMP-HSs@Fe₃O₄ could be recovered and recycled by simply applying a magnetic field. Taking advantage of their large absorption capacity, high sterilization performance, and ease of separation and recycling, CMP-HSs@Fe₃O₄ may have remarkable potential for practical applications in separation, purification, and water treatment, etc.