Research Article
Optimization of Aqueous Two-Phase Systems for the Recovery of Soluble Proteins from Tannery Wastewater Using Response Surface Methodology
Table 2
Central composite design (CCD) of variables with % recovery as response.
| Experiment no. | | Codeda and uncodedb values of variables | Recovery, (%) | | pH | NaCl (M) | Temperature (°C) | Experimental | Predicted |
| 1 | | 6.4 (−1) | 0.14 (−1) | 24 (−1) | 76.78 | 78.30 | 2 | | 7.6 (+1) | 0.14 (−1) | 24 (−1) | 87.69 | 86.51 | 3 | | 6.4 (−1) | 0.26 (+1) | 24 (−1) | 79.68 | 78.88 | 4 | 23 Factorial points | 7.6 (+1) | 0.26 (+1) | 24 (−1) | 84.35 | 84.82 | 5 | 6.4 (−1) | 0.14 (−1) | 35 (+1) | 88.90 | 88.45 | 6 | | 7.6 (+1) | 0.14 (−1) | 36 (+1) | 89.56 | 90.39 | 7 | | 6.4 (+1) | 0.26 (+1) | 36 (+1) | 76.85 | 78.06 | 8 | | 7.6 (−1) | 0.26 (+1) | 36 (+1) | 79.21 | 77.72 |
| 9 | | 7 (0) | 0.2 (0) | 30 (0) | 90.66 | 89.81 | 10 | I set of center points | 7 (0) | 0.2 (0) | 30 (0) | 90.50 | 89.81 | 11 | | 7 (0) | 0.2 (0) | 30 (0) | 89.65 | 89.81 |
| 12 | | 6 (−1.68) | 0.2 (0) | 30 (0) | 83.22 | 82.36 | 13 | | 8 (+1.68) | 0.2 (0) | 30 (0) | 88.15 | 88.98 | 14 | Star points | 7 (0) | 0.1 (−1.68) | 30 (0) | 92.46 | 92.05 | 15 | 7 (0) | 0.3 (+1.68) | 30 (0) | 81.51 | 81.88 | 16 | | 7 (0) | 0.2 (0) | 20 (−1.68) | 88.62 | 83.64 | 17 | | 7 (0) | 0.2 (0) | 40 (+1.68) | 78.55 | 78.51 |
| 18 | | 7 (0) | 0.2 (0) | 30 (0) | 89.56 | 89.81 | 19 | II set of center points | 7 (0) | 0.2 (0) | 30 (0) | 88.62 | 89.81 | 20 | | 7 (0) | 0.2 (0) | 30 (0) | 89.85 | 89.81 |
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