Analysis of variance (ANOVA) for colour removal efficiencya.
| Source | Sum of squares | df | Mean square | F-Value | p-Value |
|---|---|---|---|---|---|
| Fe/AC | |||||
| Model | 425.8 | 7 | 60.8 | 45.4 | <0.0001 |
| A – dosage of H2O2 | 8.8 | 1 | 8.8 | 6.5 | 0.0184 |
| B – dosage of adsorbent | 283.1 | 1 | 283.1 | 211.5 | <0.0001 |
| C – pH | 60.3 | 1 | 60.3 | 45.0 | <0.0001 |
| D – reaction time | 27.2 | 1 | 27.2 | 20.3 | 0.0002 |
| AB | 4.7 | 1 | 4.7 | 3.5 | 0.0763 |
| BC | 32.1 | 1 | 32.1 | 24.0 | <0.0001 |
| CD | 10.0 | 1 | 10.0 | 7.4 | 0.0126 |
| Lack of fit | 22.4 | 16 | 1.4 | 1.2 | 0.4462 |
| R-squared | 0.938 | ||||
| Adj R-squared | 0.917 | ||||
| Pred R-squared | 0.871 | ||||
| Adeq. precision | 24.6 | ||||
| Eqn (3) | 76.7–0.6A + 3.4B − 1.7C − 1.2D + 0.5AB + 1.4BC + 0.8CD | ||||
| Zeolite-Fe/AC | |||||
| Model | 10 098.0 | 9 | 1122.0 | 322.2 | <0.0001 |
| A – dosage of H2O2 | 481.9 | 1 | 481.9 | 138.4 | <0.0001 |
| B – dosage of adsorbent | 2676.5 | 1 | 2676.5 | 768.6 | <0.0001 |
| C – pH | 5557.0 | 1 | 5557.0 | 1595.9 | <0.0001 |
| D – reaction time | 42.0 | 1 | 42.0 | 12.1 | 0.0025 |
| AB | 51.7 | 1 | 51.7 | 14.8 | 0.0011 |
| AC | 130.8 | 1 | 130.8 | 37.6 | <0.0001 |
| BC | 68.7 | 1 | 68.7 | 19.7 | 0.0003 |
| CD | 29.8 | 1 | 29.8 | 8.6 | 0.0086 |
| C^2 | 3188.5 | 1 | 3188.5 | 915.7 | <0.0001 |
| Lack of fit | 61.4 | 14 | 4.4 | 4.6 | 0.0511 |
| R-squared | 0.993 | ||||
| Adj R-squared | 0.990 | ||||
| Pred R-Squared | 0.980 | ||||
| Adeq. precision | 62.8 | ||||
| Eqn (4) | 45.4 + 4.5A + 10.6B − 17.8C + 1.3D − 1.8AB + 2.9AC − 2.1BC − 1.4CD | ||||
a
A: dosage of H2O2, B: dosage of adsorbent, C: pH value, D: reaction time.