Research Article
The Effect of Vacuum Annealing of Magnetite and Zero-Valent Iron Nanoparticles on the Removal of Aqueous Uranium
Table 1
Bulk and surface properties of the nanomaterials.
| | Parameter | Analytical technique | | Nano-Fe0 | VA-nano-Fe0 | Nano-Fe3O4 | VA-Nano-Fe3O4 |
| | Particle size distribution (%) |
XPS | 0–60 nm | 85 | 84 | 98 | 96 | | 60–100 nm | 8 | 7 | 2 | 4 | | >100 nm | 7 | 9 | 0 | 0 | | Crystallinity | XRD | | Highly disordered/amorphous (α-Fe) | Crystalline (α-Fe, Fe2B) | Crystalline (Fe3O4) | Crystalline (Fe3O4) | | Oxide thickness (nm) | TEM | | 3-4 | 2 | — | — | | Surface area (m2 g−1) | BET | | 14.77 | 5.24 | 54.47 | 42.45 | | Surface composition (%) |
XPS | Fe | 40.5 | 22.5 | 21.51 | 26.78 | | O | 32.1 | 32.4 | 47.62 | 50.08 | | C | 14.5 | 19.1 | 30.81 | 23.14 | | B | 12.9 | 26.1 | — | | | Surface chemistry |
XPS | (Fe0/Fe2+ + Fe3+) | 0.03 | 0.135 | — | — | | Fe2+/Fe3+ | 0.33 | 0.45 | 0.31 | 0.30 |
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