Table 3 Experimental design and results of the Box–Behnken design for the decolourization of MG by nano-bentonite and MgO impregnated clay
Run | pH | Concentration | Temperature | Dosage | Nano-bentonite | MgO impregnated clay |
|---|---|---|---|---|---|---|
1 | 0 | 0 | 0 | 0 | 97.13 | 90.08 |
2 |  − 1 | 0 | 0 |  − 1 | 92.429 | 91.41 |
3 | 0 | 0 | 0 | 0 | 97.212 | 93.71 |
4 | 0 | 0 | 0 | 0 | 97.114 | 96.6 |
5 | 0 | 1 | 0 | 1 | 97.212 | 97.32 |
6 | 1 | 0 | 0 | 1 | 98.409 | 97.2 |
7 | 0 |  − 1 | 0 | 1 | 96.51 | 98.95 |
8 | 0 | 1 | 1 | 0 | 96.118 | 97.18 |
9 |  − 1 | 0 | 1 | 0 | 92.401 | 93.05 |
10 | 0 | 1 | 0 |  − 1 | 96.016 | 96.41 |
11 | 1 | 0 | 0 |  − 1 | 97.392 | 93.89 |
12 | 0 | 0 | 1 |  − 1 | 98.05 | 97.91 |
13 | 0 |  − 1 | 0 |  − 1 | 98.72 | 97.01 |
14 | 0 | 0 |  − 1 |  − 1 | 96.413 | 97.85 |
15 | 0 | 0 |  − 1 | 1 | 97.119 | 98.85 |
16 |  − 1 | 1 | 0 | 0 | 90.015 | 97.012 |
17 | 0 |  − 1 | 1 | 0 | 98.812 | 94.91 |
18 | 1 | 0 | 1 | 0 | 96.47 | 95.81 |
19 | 0 |  − 1 |  − 1 | 0 | 96.312 | 94.81 |
20 |  − 1 | 0 | 0 | 1 | 90.062 | 97.51 |
21 |  − 1 |  − 1 | 0 | 0 | 92.32 | 94.15 |
22 | 1 |  − 1 | 0 | 0 | 97.84 | 96.05 |
23 | 1 | 0 |  − 1 | 0 | 98.382 | 95.029 |
24 | 0 | 0 | 0 | 0 | 97.3 | 92.0 |
25 |  − 1 | 0 |  − 1 | 0 | 89.616 | 96.94 |
26 | 0 | 1 |  − 1 | 0 | 97.162 | 92.04 |
27 | 0 | 0 | 0 | 0 | 97.8 | 98.51 |
28 | 0 | 0 | 1 | 1 | 96.982 | 99.77 |
29 | 1 | 1 | 0 | 0 | 97.318 | 90.08 |