Formation of Dense and High-Aspect-Ratio Iron Oxide Nanowires by Water-Vapor-Assisted Thermal Oxidation and their Cr(VI) Adsorption Properties

Abstract

In this work, highly crystalline and high aspect ratio α-Fe2O3 nanowire (NWs) were successfully produced by thermal oxidation of iron in water vapor at 800°C. The process was done for 2 h and the NWs were found to be covering the foil uniformly unlike when the oxidation environment was dry whereby the NWs formed were shorted and rather dispersed. The formation of NWs was proposed to be due to a stress-driven surface diffusion during thermal oxidation process. When oxidation was done at 700 oC, we observed coral-like nanostructures. The α-Fe2O3 NWs were then used as adsorbent to remove Cr(VI) from stimulated wastewater. Removal efficiency of 97% in a 225 mg/L Cr(VI) solution was observed indicating very fast removal of Cr(VI) in the presence of the NWs. The kinetic characteristic of the adsorption was fitted to a pseudo-second-order kinetic model, and isothermal studies indicated that the α-Fe2O3 NWs exhibited an adsorption capacity of 66.26 mg/g.

H2O2-Free Sunlight-Promoted Photo-Fenton-Type Removal of Hexavalent Chromium Using Reduced Iron Oxide Dust

“…8−11 Presently, numerous methods 12 involving the usage of iron-based materials/nanomaterials 13 for the removal of Cr(VI) have already been present. These mostly describe the adsorptive removal capability of iron-based catalysts to remove Cr(VI) from wastewater, such as biochar-based iron oxide composites (FeYBCs), 14 CTAB-coated iron oxides, 15 aluminum oxide−iron oxide films (Al 2 O 3 −Fe 2 O 3 films), 16 zero-valent iron nanoparticles (ZVI), 17 iron oxide nanowires (α-Fe 2 O 3 NWs), 18 humic acid coated on magnetite (HA-Fe 3 O 4 ), 19 phytofabricated iron nanoparticles, 20 γ-Fe 2 O 3carbon hybrids, 21 etc. Only a few reports focusing on the photocatalytic reduction of Cr(VI) to Cr(III) using some light sources are available.…”