From metal-organic frameworks to magnetic nanostructured porous carbon composites: towards highly efficient dye removal and degradation

摘要

A magnetic nanostructured porous carbon material (gamma-Fe2O3/C) was easily synthesized using a microwave-enhanced high-temperature ionothermal method with an iron terephthalate metal-organic framework MIL-53(Fe), as a template. The structure, morphology, magnetic properties, and porosity of gamma-Fe2O3/C were characterized by powder X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, vibrating sample magnetometry, and Brunauer-Emmett-Teller surface area analysis. The obtained porous carbon materials (gamma-Fe2O3/C), possessed a high specific surface area (397.2 m(2) g(-1)) and pore volume (0.495 cm(2) g(-1)). The adsorption properties were tested by removal of malachite green (MG) from an aqueous solution. After reaching adsorption equilibrium, the maximum adsorption capacity was 499 mg g(-1) at 30 degrees C, and reached 863 mg g(-1) at 60 degrees C. The excellent magnetism (20.10 emu g(-1)) provided an ideal magnetic-separation performance. Analysis of the sorption kinetics and isotherms showed that these sorption processes were better fitted to the pseudo-second-order and Langmuir equations than pseudo-first-order and Freundlich equations. Various thermodynamic parameters, such as Delta G(theta), Delta S-theta, and Delta H-theta, were also calculated, and indicated that the present system was spontaneous and endothermic. It was further demonstrated that gamma-Fe2O3 showed powerful photocatalytic activity for the degradation of MG under sunlight in the presence of H2O2.