Table 1 Levels of the parameters using face-centered central composite design (FC-CCD)
Independent Variables | Unit | Symbol | Levels | ||
|---|---|---|---|---|---|
− 1 | 0 | + 1 | |||
pH | - | X1 | 4.0 | 7.5 | 11.0 |
Salinity | mg/L | X2 | 40,000 | 75,000 | 110,000 |
Surfactant concentration | wt.% | X3 | 2 | 4 | 6 |
Independent Variables | Unit | Symbol | Levels | ||
|---|---|---|---|---|---|
− 1 | 0 | + 1 | |||
pH | - | X1 | 4.0 | 7.5 | 11.0 |
Salinity | mg/L | X2 | 40,000 | 75,000 | 110,000 |
Surfactant concentration | wt.% | X3 | 2 | 4 | 6 |