| Contact time (h) | Initial concentration (mg) | Dose (gm) | pH | Amount of phosphate adsorbed (mg/g) | Desirability |
| 4.55 | 250 | 0.1 | 4.19 | 55.82 | 0.997 |
| 4.43 | 250 | 0.1 | 4.21 | 55.81 | 0.996 |
| 4.4 | 250 | 0.1 | 4.24 | 55.71 | 0.994 |