Research Article

Optimization of Aqueous Two-Phase Systems for the Recovery of Soluble Proteins from Tannery Wastewater Using Response Surface Methodology

Table 1

Coded and uncoded values of factors of 25–1 fractional factorial design (fFD).

Experiment no.Codeda and uncodedb values of variablesRecovery (%)
PEG (% w/w)SC (% w/w)pHNaCl (M)Temperature (°C)

112 (−1)23(+1)8 (+1)0.3 (+1)20 (−1)67.24
220 (+1)15 (−1)8 (+1)0.1 (−1)40 (+1)68.24
312 (−1)15 (−1)6 (−1)0.1 (−1)40 (+1)33.95
420 (+1)23 (+1)8 (+1)0.3 (+1)40 (+1)83.42
512 (−1)23 (+1)6 (−1)0.3 (+1)40 (+1)52.71
612 (−1)23 (+1)8 (+1)0.1 (−1)40 (+1)50.49
720 (+1)23 (+1)8 (+1)0.1 (−1)20 (−1)52.21
812 (−1)23 (+1)6 (−1)0.1 (−1)20 (−1)37.29
920 (+1)15 (−1)6 (−1)0.1 (−1)20 (−1)29.89
1020 (+1)15 (−1)8 (+1)0.3 (+1)20 (−1)71.77
1120 (+1)23 (+1)6 (−1)0.3 (+1)20 (−1)54.59
1220 (+1)15 (−1)6 (−1)0.3 (+1)40 (+1)64.49
1312 (−1)15 (−1)8 (+1)0.3 (+1)40 (+1)75.33
1412 (−1)15 (−1)8 (+1)0.1 (−1)20 (−1)61.46
1520 (+1)23 (+1)6 (−1)0.1 (−1)40 (+1)48.93
1612 (−1)15 (−1)6 (−1)0.3 (+1)20 (−1)58.49

aData in brackets; bData without brackets.