Sacrificial Zinc Oxide Strategy-Enhanced Mesoporosity in MIL-53-Derived Iron–Carbon Composite for Methylene Blue Adsorption

Abstract

MOF-derived carbon-based materials have attracted widespread attention due to their relatively large surface area, morphology, and their stability in water. Considering these advantages, these materials present themselves as excellent adsorbents. In this work, a novel method was designed for the fabrication of a nano zero-valent-iron (nZVI) carbon composite. The utilization of zinc oxide nanorods (ZnONRs) in the role of sacrificial consumable nuclei for the synthesis of MIL-53 sacrificial zinc oxide nanorods (MIL-53-SNR) and the subsequent pyrolysis at 700 °C in the inert atmosphere led to a graphitic-supported nZVI material (Fe-C-SNR). Fe-C-SNR was compared with a commercial zinc oxide bulk (MIL-53-SB) and with a pristine MIL-53. By virtue of the ZnONRs, Fe-C-SNR exhibited a greatly improved mesoporous structure. Consequently, the pyrolyzed materials were applied as adsorbents for methylene blue. Fe-C-SNR’s performance increased to more than double of the pyrolyzed MIL-53 (Fe-C), with a remarkably fast adsorption time (10 min) for a concentration of 10 mg L−1 with only 200 mg L−1 adsorbent required. This functional composite also displayed exceptional recyclability; after ten complete cycles, Fe-C-SNR was still capable of completely adsorbing the methylene blue. The utilization of ZnONRs proves itself advantageous and could further be extended to other MOFs for a wide range of applications.

New Advances into Nanostructured Oxides

“…Dekyvere et al [18] reported a novel strategy for the fabrication of nano zero-valentiron (nZVI) carbon-based mesoporous materials derived from iron-containing metalorganic frameworks (MOFs) using zinc oxide nanorods as sacrificial nuclei. Here, the breakthrough idea is the utilization of the nanostructured zinc oxide under the shape of nanorods (i.e., aspect ratio 10) as sacrificial consumable nuclei for shaping the final highly porous materials (with specific surface area in the 185-270 m 2 /g range).…”