Table 1.
Values of the 23 + star central composite factorial design, parameters, and responses
| Independent variables | Dependent variables/responses | ||||||
|---|---|---|---|---|---|---|---|
| TH | TW | pH | Zav (nm) | PI | ZP (mV) | EE (%) | |
| Factorial points | |||||||
| F1 | − 1 | − 1 | − 1 | 217.9 ± 1.2 | 0.112 ± 0.001 | − 30.7 ± 0.9 | 76.35 ± 1.53 |
| F2 | 1 | − 1 | − 1 | 234.9 ± 2.1 | 0.093 ± 0.004 | − 29.9 ± 0.4 | 79.16 ± 0.18 |
| F3 | − 1 | 1 | − 1 | 176.2 ± 1.0 | 0.075 ± 0.023 | − 27.7 ± 1.3 | 76.67 ± 2.17 |
| F4 | 1 | 1 | − 1 | 174.0 ± 0.6 | 0.081 ± 0.012 | − 28.3 ± 0.8 | 80.07 ± 3.65 |
| F5 | − 1 | − 1 | 1 | 162.0 ± 0.4 | 0.072 ± 0.011 | − 26.2 ± 0.3 | 79.64 ± 3.79 |
| F6 | 1 | − 1 | 1 | 163.5 ± 1.4 | 0.071 ± 0.009 | − 23.6 ± 0.5 | 73.52 ± 1.83 |
| F7 | − 1 | 1 | 1 | 183.9 ± 0.4 | 0.087 ± 0.020 | − 29.5 ± 0.1 | 78.41 ± 2.51 |
| F8 | 1 | 1 | 1 | 172.4 ± 1.1 | 0.094 ± 0.009 | − 26.6 ± 0.3 | 76.60 ± 5.60 |
| Axial points | |||||||
| F9 | 1.68 | 0 | 0 | 174.2 ± 0.6 | 0.061 ± 0.018 | − 25.2 ± 0.4 | 77.01 ± 3.07 |
| F10 | − 1.68 | 0 | 0 | 176.7 ± 1.1 | 0.083 ± 0.033 | − 23.6 ± 0.3 | 73.55 ± 2.93 |
| F11 | 0 | 1.68 | 0 | 187.1 ± 0.8 | 0.024 ± 0.006 | − 23.1 ± 0.6 | 71.38 ± 0.62 |
| F12 | 0 | − 1.68 | 0 | 167.4 ± 2.1 | 0.046 ± 0.021 | − 26.1 ± 0.4 | 76.92 ± 2.47 |
| F13 | 0 | 0 | 1.68 | 164.6 ± 1.1 | 0.057 ± 0.010 | − 23.1 ± 0.8 | 72.44 ± 1.66 |
| F14 | 0 | 0 | − 1.68 | 202.6 ± 3.5 | 0.063 ± 0.045 | − 22.5 ± 1.1 | 82.89 ± 6.01 |
| Central points | |||||||
| F15 | 0 | 0 | 0 | 175.4 ± 2.1 | 0.053 ± 0.013 | − 24.5 ± 0.6 | 74.94 ± 1.77 |
| F16 | 0 | 0 | 0 | 176.3 ± 1.9 | 0.072 ± 0.016 | − 25.3 ± 0.7 | 78.14 ± 0.49 |