Table 1 Central composite design matrix, experimental and predicted values for response surface analysis
Run | Independent variables | Response | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Coded value | Actual value | DH (%) | ||||||||
x 1 | x 2 | x 3 | x 4 | T1 (°C) | C2 (%) | pH | Time (h) | Observed | Predicted | |
1 | −1 | 1 | 1 | −1 | 45 | 18 | 8.0 | 6.0 | 25.45 | 25.42 |
2 | −1 | 1 | 1 | 1 | 45 | 18 | 8.0 | 7.0 | 26.46 | 26.99 |
3 | 1 | 1 | −1 | −1 | 55 | 18 | 7.0 | 6.0 | 28.77 | 28.58 |
4 | 2 | 0 | 0 | 0 | 60 | 16 | 7.5 | 6.5 | 23.64 | 24.14 |
5 | 0 | 2 | 0 | 0 | 50 | 20 | 7.5 | 6.5 | 30.66 | 30.77 |
6 | 0 | 0 | 0 | 0 | 50 | 16 | 7.5 | 6.5 | 31.26 | 31.91 |
7 | 0 | 0 | 0 | 0 | 50 | 16 | 7.5 | 6.5 | 31.46 | 31.91 |
8 | 1 | −1 | −1 | −1 | 55 | 14 | 7.0 | 6.0 | 28.14 | 27.73 |
9 | 1 | -1 | -1 | 1 | 55 | 14 | 7.0 | 7.0 | 30.55 | 30.83 |
10 | 1 | -1 | 1 | 1 | 55 | 14 | 8.0 | 7.0 | 31.68 | 31.54 |
11 | 0 | 0 | 0 | 0 | 50 | 16 | 7.5 | 6.5 | 32.16 | 31.91 |
12 | −2 | 0 | 0 | 0 | 40 | 16 | 7.5 | 6.5 | 19.13 | 18.27 |
13 | −1 | −1 | 1 | −1 | 45 | 14 | 8.0 | 6.0 | 25.82 | 26.15 |
14 | 1 | 1 | −1 | 1 | 55 | 18 | 7.0 | 7.0 | 31.17 | 30.96 |
15 | 0 | 0 | 0 | 0 | 50 | 16 | 7.5 | 6.5 | 31.81 | 31.91 |
16 | 0 | 0 | 0 | 0 | 50 | 16 | 7.5 | 6.5 | 32.56 | 31.91 |
17 | 1 | −1 | 1 | −1 | 55 | 14 | 8.0 | 6.0 | 28.30 | 28.56 |
18 | −1 | 1 | −1 | −1 | 45 | 18 | 7.0 | 6.0 | 25.54 | 25.80 |
19 | −1 | 1 | −1 | 1 | 45 | 18 | 7.0 | 7.0 | 27.50 | 27.49 |
20 | 0 | 0 | −2 | 0 | 50 | 16 | 6.5 | 6.5 | 29.79 | 29.83 |
21 | 0 | 0 | 0 | 0 | 50 | 16 | 7.5 | 6.5 | 32.38 | 31.91 |
22 | 1 | 1 | 1 | −1 | 55 | 18 | 8.0 | 6.0 | 28.97 | 28.86 |
23 | 0 | 0 | 0 | 2 | 50 | 16 | 7.5 | 7.5 | 33.61 | 33.27 |
24 | −1 | −1 | −1 | 1 | 45 | 14 | 7.0 | 7.0 | 28.15 | 28.38 |
25 | 0 | 0 | 2 | 0 | 50 | 16 | 8.5 | 6.5 | 30.57 | 30.16 |
26 | 0 | −2 | 0 | 0 | 50 | 12 | 7.5 | 6.5 | 31.84 | 31.36 |
27 | 0 | 0 | 0 | −2 | 50 | 16 | 7.5 | 5.5 | 28.63 | 28.60 |
28 | 1 | 1 | 1 | 1 | 55 | 18 | 8.0 | 7.0 | 31.21 | 31.12 |
29 | −1 | −1 | 1 | 1 | 45 | 14 | 8.0 | 7.0 | 28.00 | 28.44 |
30 | −1 | −1 | −1 | −1 | 45 | 14 | 7.0 | 6.0 | 25.64 | 25.98 |