Table 1.
Microstructural parameters of synthesized magnetite nanoparticles (MNPs). HA—humic acids.
| Sample | Fe3O4 | Fe3O4/HA | Fe3O4/HA Harsh Oxidation | Fe3O4/HA Mild Oxidation | ||||
|---|---|---|---|---|---|---|---|---|
| hkl | 2θ, ° | d, Å | 2θ, ° | d, Å | 2θ, ° | d, Å | 2θ, ° | d, Å |
| 220 | 45.60 | 2.971 | 45.67 | 2.966 | 45.62 | 2.954861 | 49.33 | 2.74502038 |
| 311 | 53.98 | 2.535 | 54.01 | 2.535 | 53.92 | 2.526709 | 53.92 | 2.52670925 |
| 400 | 66.28 | 2.094 | 66.36 | 2.094 | 66.39 | 2.09233 | - | - |
| 422 | 84.25 | 1.714 | 84.25 | 1.714 | 84.38 | 1.705695 | 82.6 | 1.73564713 |
| 511 | 90.77 | 1.610 | 90.71 | 1.612 | 90.62 | 1.61133 | 92.69 | 1.58329633 |
| 440 | 101.52 | 1.476 | 101.4 | 1.476 | 101.68 | 1.477368 | 101.3 | 1.48137719 |
| a, A | 8.383(2) | 8.382(6) | 8.365(5) | 8.250(8) | ||||
| x | 0.387(7) | 0.382(1) | 0.232(7) | - | ||||
| δ | 0.059(4) | 0.062(7) | 0.154(2) | - | ||||
| Fe3-δO4 | Fe2.94O4 | Fe2.93O4 | Fe2.84O4 | - | ||||
| % Fe3O4 | ~82.7 | ~79.2 | ~48.3 | 0 | ||||
| D, nm | 6.9 ± 2.4 | 10.3 ± 1.3 | 7.8 ± 1.9 | 11.03 ± 5.1 | ||||
| CV, % | 34 | 12.6 | 24.6 | 50.2 | ||||
% Fe3O4 is the content of stoichiometric magnetite, CV—coefficient of variation.