Table 1 The CCD matrix
From: Optimization of variables for cadmium and copper removal using magnetic nanocomposite
Variables | Unit | Symbols | Level of variables | |||||
|---|---|---|---|---|---|---|---|---|
− α | − 1 | 0 |  + 1 |  + α | ||||
Concentration | Mg L−1 | A | 10 | 20 | 30 | 40 | 50 | |
pH of solution | – | B | 2 | 3 | 4 | 5 | 6 | |
Composite amount | g | C | 0.10 | 0.15 | 0.20 | 0.25 | 0.30 | |
Ultrasound radiation time | min | D | 5 | 10 | 15 | 20 | 25 | |