Table 2 The information of the selected factors
Factor | Name | Units | Lower code (-1) | Upper code (1) | Mean | Std. Dev. |
|---|---|---|---|---|---|---|
A | pH | - | 2 | 10 | 6 | 2.4 |
B | Contact time | min | 5 | 150.00 | 77.5 | 35.8 |
C | Adsorbent dosage | g L−1 | 0.1 | 0.8 | 0.45 | 0.18 |
D | Temperature | °C | 30 | 50 | 40 | 9 |
E | Initial concentration | mg L−1 | 30 | 200 | 115 | 51 |