Insight into Core–Shell Dependent Anoxic Cr(VI) Removal with Fe@Fe₂O₃ Nanowires: Indispensable Role of Surface Bound Fe(II)

Abstract

In this study, we investigated the anoxic Cr(VI) removal with core-shell Fe@Fe2O3 nanowires. It was found the surface area normalized Cr(VI) removal rate constants of Fe@Fe2O3 nanowires first increased with increasing the iron oxide shell thickness and then decreased, suggesting that Fe@Fe2O3 nanowires possessed an interesting core-shell structure dependent Cr(VI) removal property. Meanwhile, the Cr(VI) removal efficiency was positively correlated to the amount of surface bound Fe(II). This result revealed that the core-shell structure dependent Cr(VI) removal property of Fe@Fe2O3 nanowires was mainly attributed to the reduction of Cr(VI) by the surface bound Fe(II) besides the reduction of Cr(VI) adsorbed on the iron oxide shell via the electrons transferred from the iron core. The indispensable role of surface bound Fe(II) was confirmed by Tafel polarization and high-resolution X-ray photoelectron spectroscopic depth profiles analyses. X-ray diffraction patterns and scanning electron microscope images of the fresh and used Fe@Fe2O3 nanowires revealed the formation of Fe(III)/Cr(III)/Cr(VI) composite oxides during the anoxic Cr(VI) removal process. This study sheds a deep insight into the anoxic Cr(VI) removal mechanism of core-shell Fe@Fe2O3 nanowires and also provides an efficient Cr(VI) removal method.

Leveraging the Potential of Endomycorrhizal Spores and Montmorillonite for Hexavalent Chromium Adsorption from Aqueous Phase

“…Elements such as C, O, N, Cr were evident in the survey scan spectra obtained (Figure a ) and the short scan of the C1s showed a peak at 283.6 eV (Figure b). The Cr 2p3/2 binding energy of 582.0 eV corresponds to Cr in the +6 oxidation state, indicating there is no perceptible reduction of Cr(III) on the AMF‐clay biosorbent surface . Hence, after biosorption there was no immediate reduction of Cr(VI) on the biosorbent surface.…”

A Core–Shell Fe/Fe2O3 Nanowire as a High‐Performance Anode Material for Lithium‐Ion Batteries

“…[45] In brief, FeCl 3 ·6H 2 O( 0.3 g) was dissolved in deionized water (100 mL) to form ac lear solution and then an aqueous solution (40 mL) NaBH 4 (0.6 g) was added to the above solution at ar ate of 0.5 mL s À1 without stirring. [45] In brief, FeCl 3 ·6H 2 O( 0.3 g) was dissolved in deionized water (100 mL) to form ac lear solution and then an aqueous solution (40 mL) NaBH 4 (0.6 g) was added to the above solution at ar ate of 0.5 mL s À1 without stirring.…”

Adsorption of chromium supported with various column modelling studies through the synergistic influence of Aspergillus and cellulose

“…The amplified narrow scan spectra of Cr 2p3/2 has a binding energy of 576.8 eV (Fig. 2B) characteristic of Cr(III) [42] and 587.6 eV which is the peak due to Cr (VI). In the present study, during the adsorption of hexavalent chromium there was no abrupt reduction of Cr(VI) to Cr(III) and it was only after 3 days a pale green coloration was observed on the surface of the biosorbent indicating the probable reduction to Cr(III) and it was also supported through the XPS characterization.…”