Independent variables
Levels
initial concentration (mg/L)
-α
a
-1
0
1
+α
pH
5
15
25
35
45
time (min)
2
4
6
8
10
Dosage (g)
5
25
45
65
85
initial concentration (mg/L)
0.5
1.0
1.5
2.0
2.5
a
α=2, calculated by Minitab software
Table 1:
Range of Values of Central Composite Design.
