A Core–shell Fe3O4@NH2-MIL-101(Cr) Composite Material for Efficient Removal of Formaldehyde

In this study, Fe3O4@NH2-MIL-101(Cr) was successfully synthesized by an in situ hydrothermal method for HCHO removal. The results revealed that NH2-MIL-101(Cr) particles were evenly dispersed on the surface of Fe3O4 and had a well-defined core–shell structure of about 300 nm. When compared to pure MIL-101(Cr), Fe3O4@NH2-MIL-101(Cr) exhibited a significantly improved adsorption performance for HCHO removal, with a maximum adsorption capacity of 81.30 mg g−1. The HCHO removal rates remained above 90% after five adsorption–desorption experiments, and there was no apparent collapse or microstructure change, indicating that the Fe3O4@NH2-MIL-101(Cr) had excellent stability and recycling. The adsorption was primarily based on interactions between the amine group on the MOF and HCHO, with the N elements serving as the main active adsorbent sites for the HCHO. The results show that the amine-functionalized materials have excellent application potential in practical HCHO adsorption. Effective adsorption removal of HCHO with FNM-0.2