Magnetic Metal–Organic Framework (Fe3O4@MIL-101) Functionalized with Dendrimer: Highly Efficient and Selective Adsorption Removal of Organic Dyes

Herein, a magnetic chromium-based metal–organic framework (MOF) was successfully synthesized and applied for adsorption and removal of methylene blue MB and methyl orange MO from an aqueous solution. To achieve high adsorption capacity and selective removal of organic dyes, rational surface functionalization of synthesized MOF with poly (propylene imine) PPI dendrimer was carried out. The Fe 3 O 4 @MIL-101@PPI composite exhibits a crystalline structure with high thermal stability and magnetic properties. In addition, this framework shows a high specific surface area (116 m 2 /g) and porosity which is beneficial for wastewater treatment. The results indicate that Fe 3 O 4 @MIL-101@PPI composite can remove cationic dye from an aqueous solution more selectively and efficiently than anionic dye. The adsorption experiments revealed high adsorption capacity (93.9 mg/g) and fast adsorption kinetics following the pseudo-second-order kinetic model. Interestingly, the regeneration study showed that the Fe 3 O 4 @MIL-101@PPI composite had appropriate reusability for dye removal with an almost unchanged structure after five regeneration cycles. This research provides new insights for the rational design of hybrid magnetic adsorbents with synergistic functionality and porous structure by combining the advantages of magnetic nanoparticles, MOFs, and dendrimers. Graphical Abstract