Magnetic Fe3O4 Nanoparticle/ZIF-8 Composites for Contaminant Removal from Water and Enhanced Flame Retardancy of Flexible Polyurethane Foams

In order to separate heavy-metal ions from contaminated wastewater and further realize the reutilization of waste adsorbent, magnetic composites with flowerlike structure were successfully synthesized. After the absorption of Cu2+ ions, hybrids can be used as effective coatings to enhance the fire safety of flexible polyurethane foam (FPUF) through a dip-coating method. As-fabricated metal–organic framework (MOF)-based composites exhibited a core–shell and flowerlike structure with high thermal stability. The maximum adsorption capacity for Cu2+ could reach 292.13 mg·g–1, calculated from the Langmuir isotherm model. In order to reutilize the adsorbed Cu2+ ions, the CuO-loaded MOF-derived Fe3O4@ZnO@CuO (MO) was obtained with a simple heat treatment. The effectivity of MO as a fire-safety coating for inhibiting the release of heat and toxic gases of FPUF was satisfactory. The application of this MOF-based composite will provide useful insights into the design of bifunctional materials for efficient wastewater remediation and fire-safety coatings.