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 variablesRecovery, (%)
pHNaCl (M)Temperature (°C)ExperimentalPredicted

16.4 (−1) 0.14 (−1)24 (−1)76.7878.30
27.6 (+1)0.14 (−1)24 (−1)87.6986.51
36.4 (−1)0.26 (+1)24 (−1)79.6878.88
423 Factorial points7.6 (+1)0.26 (+1)24 (−1)84.3584.82
56.4 (−1)0.14 (−1)35 (+1)88.9088.45
67.6 (+1)0.14 (−1)36 (+1)89.5690.39
76.4 (+1)0.26 (+1)36 (+1)76.8578.06
87.6 (−1)0.26 (+1)36 (+1)79.2177.72

97 (0)0.2 (0)30 (0)90.6689.81
10I set of center points7 (0)0.2 (0)30 (0)90.5089.81
117 (0)0.2 (0)30 (0)89.6589.81

126 (−1.68)0.2 (0)30 (0)83.2282.36
138 (+1.68)0.2 (0)30 (0)88.1588.98
14Star points7 (0)0.1 (−1.68)30 (0)92.4692.05
157 (0)0.3 (+1.68)30 (0)81.5181.88
167 (0)0.2 (0)20 (−1.68)88.6283.64
177 (0)0.2 (0)40 (+1.68)78.5578.51

187 (0)0.2 (0)30 (0)89.5689.81
19II set of center points7 (0)0.2 (0)30 (0)88.6289.81
207 (0)0.2 (0)30 (0)89.8589.81