Table 1 The levels and ranges of variables central composite statistical experiment design
Factor | Name | Low actual | High actual | Low coded | High coded | Mean | Std. dev |
|---|---|---|---|---|---|---|---|
A | pH | 5.25 | 9.75 | −1.000 | 1.000 | 7.500 | 2.012 |
B | Contact time (min) | 37.50 | 92.50 | −1.000 | 1.000 | 65.000 | 24.597 |
C | Acetamipraid (mg/L) | 10.75 | 30.25 | −1.000 | 1.000 | 20.500 | 8.721 |
D | Dose of NPa (mg/L) | 325.00 | 775.00 | −1.000 | 1.000 | 550.000 | 201.246 |