Design matrix for three coded variables together with the actual and predicted responsesa.
| Runs | Coded values of the variables | ||||||
|---|---|---|---|---|---|---|---|
| X 1 | X 2 | X 3 | Y 1 | Ŷ 1 | Y 2 | Ŷ 2 | |
| 1 | −1.00 | −1.00 | 0.00 | 51.300 | 51.200 | 44.80 | 46.462 |
| 2 | 1.00 | −1.00 | 0.00 | 65.300 | 65.200 | 24.50 | 26.163 |
| 3 | −1.00 | 1.00 | 0.00 | 72.700 | 72.800 | 63.40 | 61.737 |
| 4 | 1.00 | 1.00 | 0.00 | 77.000 | 77.100 | 28.90 | 27.238 |
| 5 | −1.00 | 0.00 | −1.00 | 44.300 | 44.300 | 10.60 | 10.600 |
| 6 | 1.00 | 0.00 | −1.00 | 50.500 | 50.500 | 6.50 | 6.500 |
| 7 | −1.00 | 0.00 | 1.00 | 45.500 | — | 88.40 | — |
| 8 | 1.00 | 0.00 | 1.00 | 60.600 | — | 38.60 | — |
| 9 | 0.00 | −1.00 | −1.00 | 57.900 | 58.000 | 15.20 | 13.537 |
| 10 | 0.00 | 1.00 | −1.00 | 94.800 | 94.700 | 24.90 | 26.562 |
| 11 | 0.00 | −1.00 | 1.00 | 70.500 | 70.600 | 53.10 | 51.438 |
| 12 | 0.00 | 1.00 | 1.00 | 67.500 | 67.400 | 53.10 | 54.763 |
| 13 | 0.00 | 0.00 | 0.00 | 70.000 | 71.600 | 36.90 | 39.300 |
| 14 | 0.00 | 0.00 | 0.00 | 72.400 | 71.600 | 40.50 | 39.300 |
| 15 | 0.00 | 0.00 | 0.00 | 72.400 | 71.600 | 40.50 | 39.300 |
a
X 1: adsorbent dose (g), X2: pH, X3: initial concentration (mg L−1), Y1: removal efficiency (%) and Y2: adsorption capacity (mg g−1).