Adsorption behavior of methylene blue on Fe_3O_4-embedded hybrid magnetic metal-organic framework

摘要

A magnetic hybrid material (Fe3O4-embedded-MOF) consisting of a stable metal-organic framework HKUST-1 embedded with poly(N-vinyl-2-pyrrolidone) coated Fe3O4 microspheres was simply prepared under refluxing conditions for 4h. The as-synthesized material was characterized using powder X-ray diffraction, scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), energy dispersive spectroscopy (EDS) and N-2 adsorption-desorption at 77K. The hybrid material was studied for the adsorption of methylene blue from aqueous solution. The effects of dye concentration, adsorbent dose, and initial pH on the adsorption of methylene blue were measured, and from these experimental data, adsorption isotherms, kinetics, and thermodynamics were obtained. The results showed that a pseudo-second-order kinetic model and Langmuir isotherm (with R-2=0.937) matched well for the adsorption of methylene blue onto Fe3O4-embedded-MOF. Thermodynamic parameters including free energy, enthalpy, and entropy of methylene blue adsorption were calculated, and the results showed that the adsorption of methylene blue were favorable on Fe3O4-embedded-MOF. The magnetic hybrid Fe3O4-embedded-MOF material features both magnetic separation characteristics as well as excellent adsorption performance for methylene blue in aqueous solution. The results of the present study demonstrate that Fe3O4-embedded-MOF is a promising adsorbent for the removal of dye from wastewater.