Table 3. Langmuir model parameters for the adsorption of As(V) and As(III) on Fe3O4-HBC composite at ambient temperature (25±0.8°C).
| Adsorbent | Arsenic species | Langmuir model parameters | ||
| qm (mg g−1) | k1 (L mg−1) | R 2 | ||
| Fe3O4-HBC uncalcined | As(V) | 1.288 | 109.35 | 0.9754 |
| 400°C under air | As(V) | 0.880 | 54.13 | 0.9656 |
| 400°C under nitrogen | As(V) | 0.998 | 30.06 | 0.9801 |
| 1000°C under nitrogen | As(V) | 3.355 | 254.56 | 0.9988 |
| Fe3O4-HBC uncalcined | As(III) | 1.566 | 14.96 | 0.9811 |
| 400°C under air | As(III) | 1.460 | 8.38 | 0.9753 |
| 400°C under nitrogen | As(III) | 1.308 | 5.36 | 0.9740 |
| 1000°C under nitrogen | As(III) | 3.071 | 17.57 | 0.9984 |