Precisely controlled encapsulation of Fe₃O₄ nanoparticles in mesoporous carbon nanodisk using iron based MOF precursor for effective dye removal

A facile strategy developed for the fabrication of composite material comprising mesopores and representing an iron oxide core/encapsulated in carbon nanodisk shell using Fe-based MOF as precursor. Catalytic carbonization of Fe²⁺ coordinated 1,4,5,8 -naphthaleneteracarboxylic dianhydride MOF at 725 °C under N₂ atmosphere followed by air treatment at 300 °C yielded Fe₃O₄ nanoparticles encapsulated in mesoporous carbon matrix (FeMCNA-300). The XRD and N₂ adsorption studies confirm the presence of Fe₃O₄ nanoparticles and mesopores in the carbon matrix, respectively. MOF precursor generates mesopores of narrow pore size distribution without aid of structure directing agent in the carbon shell through straightforward catalytic reduction of core iron oxide. FeMCNA-300 demonstrated outstanding catalytic activity towards the degradation of 150 ppm of methylene blue (MB) dye in water with 84% TOC conversion in 15 min at room temperature. MB and oxidant H₂O₂ interact with iron oxide nanoparticles through confined mesoporous channel in the FeMCNA-300 carbon nanodisk. This permits the generated OH[rad] at the surface of magnetite nanoparticles to instantly oxidize the MB molecules adsorbed in the close proximity. FeMCNA-300 under ultra-sonication decolourise MB completely with high TOC conversion of about 84% at maximum iron leaching of 2% up to five successive recycles.